text:
AQA Information and Communication Technology/ICT4/The Management of Change

The introduction of information systems will result in change. If this change is not managed, it is likely the IS will fail.

As a result of the 1996 OASIG study, it was discovered that
 * 80-90% of IS's do not meet performance targets
 * 80% are late or other budget
 * 40% are never completed.
 * Less than 40% fully address training and skills requirements
 * Less than 25% properly integrate business and technology objectives
 * 10-20% meet all their success criteria

Issues which need management when a system is changed

 * Skills of a workforce may not be needed under a new IS, meaning they need to be reskilled
 * They will need to be retrained to use new skills, which may be of a higher order
 * They will need to be retrained in the operational procedures, in additional to IT skills.
 * They will need to understand the consequences of not using the new system correctly.
 * Workforce attitude
 * Most people are resistant to change
 * The changes need to be completely explained
 * Users should be involved in change from an early stage.
 * Organisational structure
 * Not only may the system change, but the organisation around it may need to update their working practices for the new system
 * If responsibilites and delegations change, people may feel "left out" of the new system (middle managers may be disillusioned if their responsibilities are delegated lower down, etc.).

Why people may react badly to change

 * They fear redundancy
 * They fear a reduction in status and job satisfaction
 * Changes in organisational structure may result in a loss of promotion opportunities
 * People feel their aims and ambitions are threatened
 * People may fear that their proposals are criticising their past efforts
 * General distrust of technology
 * no one likes change especially old people

How to successfully manage change

 * Changing too much at once is a recipe for disaster.
 * Encourage people who are affected by the change to participate in the change
 * Ensure all your senior management are publically supportive of the change, and are repeatedly demonstrating this support
 * Ensure everyone has had proper training on the change
 * Make sure everyone knows why they're changing
 * Share all information and plans to everyone as soon as possible
 * Make sure that public information is not too technical for people to understand
 * Make sure everyone participates and is properly consulted
 * Divide the change into small steps to make sure people don't feel rushed into the change
 * Minimise surprises
 * Encourage motivation
 * Minimise people who "lose" from the change.


text:
Wikijunior talk:Solar System/Glossary

Several of the glossary words here are links to wikipedia articles: Atmosphere, Centaur, Erosion, Lagrange point, Near Earth Asteroid, Silicate, Tectonic Plate, and Trojan Asteroid.

In addition, some of the definitions may be too complex for the targetted audience of children: Equator, Planet.

Some of the terms themselves may also be too complex: Lagrange point.

Finally, some of the definitions are difficult or misleading: Crater, Mass, Radar, Surface Area, Star, Volume. Volume and Mass share the same definition, for example.

I'd like to help by manually editing, but I haven't familiarized myself with the policies governing editing and probably won't until this weekend. If nothing more, this can serve as my note to go back later and do so.

--

I feel that this needs to be substantially cleaned up. Be bold, and don't worry about governing policies, at least for this page. This was a pet project and was updated randomly at that.

IMHO, there should be no links to Wikipedia articles, as is the case now. This is intended to be an appendix for the Wikijunior Solar System book, and if printed there would be a need to grab information about the hyperlinked terms and write them out. Eventually I want to kill the links entirely and replace the entries with a simplified definition that would be understandable for a kid that is roughly 8-14 years old (what I try to keep in mind for a target audience when I write entries for this series). Rob Horning 6 July 2005 12:55 (UTC) I NEED TO KNOW HOW IS THE UNIVERS ?

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Wikijunior talk:Solar System/Glossary


text:
File:Cone of fire.png

The Cone of Fire is the volume of space described by the outermost trajectories of a burst of fire, if that burst of fire had intersected a vertical plane.

title: File:Cone of fire.png


text:
Movie Making Manual/Transferring large files over the Internet

If you have multiple people downloading a file
The easiest way to transfer a large file (and my interpretation of large is >50GB) would be to use BitTorrent and use your computer as a seed for the file, put a link to the seed on a free webspace provider (GeoCities, MySpace, etc.) and then communicate to the recipient where to find the link. A high speed connection would be a definite requirement, attempting this with a dial-up connection would take approximately 121 days. On a good cable connection, it would take around twenty-four hours.

Another possibility is the use of a P2P network, such as KaZaA, iMesh, or Morpheus. You could host the file, and give it a cryptic name, such as a series of numbers. Give the numbers to the recipient and have them search for it. Once their program finds your file, it will allow the recipient to download it.

Sending a large file to just a few people
The above methods will not help for transferring one file to only one or two people. In that case you have to just put it up on a (hidden) web url and just send the recipient the link to the file. Be sure that this url is not linked from other web pages or you may have search engines and webcrawlers downloading your file.

Generally, e-mail servers will not accept files larger than ten megabytes.

'''But if you have very huge files like 1GB, 10GB, 1000GB files, you can use 123Go v3.0 which is found on dorotheus.com, to transfer single file upto 16000GB. That's incredible. This program is in fact a next-generation file transfer program. You can even resume the large file transfer at your own time.'''

Your own FTP server

 * Wikipedia article on FTP

You could also run a free FTP server on your computer and ask your collaborators to connect to your FTP server. There are free servers for both Windows and Linux. If you're running Linux then give pureFTPd a go - it's very simple to setup. Don't forget to unblock port 21 on your firewall and/or router. If your're running Windows, FileZilla produces an ftp server.

Your own SSH server
SSH is a secure and fast way to send files (and commands to a Linux shell).

 * WikiPedia article on SSH

It's pretty easy to setup an SSH server on a Linux system. Almost all Linux systems have SSHd installed. First you have to log in as root, then add a new user with "useradd -m jack" then give the user a password "passwd jack". If you're using a router or a firewall then you'll have to open port 22.

It is worth noting that the encryption offered by SSH could be considered an unnecessary CPU overhead. However, there are compression features offered by SSH, so your choice to use FTP or SSH should be made based on the speed of the hardware on both ends of the line.

/Tools and equipment


text:
AQA Information and Communication Technology/ICT4/Legal Aspects

Corporate Information Systems Security Policies
A corporate information systems (IS) security policy exists to protect the company from threat. This security policy should be part of the organisations strategic management. It is important to get it right as

 * costs are involved in providing the security the company needs to protect itself
 * users are sceptical of computer systems for security and are highly aware of the risks involved People don't want to be involved in a company that is known to be insecure

IS security policies exist to

 * secure systems against loss of availability, integrity or confidentiality
 * prevent and detecting misuse, both against the relevant Acts and the company's internal policies
 * investigate and deal with any misuse based on the procedures laid out in the policy
 * limit and recover from damage

The three lines of defence in IS security are:

 * 1) prevention
 * 2) detection
 * 3) recovery

The corporate IS policy should include considerations to training and promoting awareness of general security to the end-users of the system, as that is where lapses in security are likely to happen.

They should be educated on matters such as downloading unknown executables from the Internet, or not using easy to guess, common passwords.

Audit Requirements
An audit is a survey taken by a company of its software and hardware. An audit exists to minimise errors of the company's resources database (often used for insurance purposes), to monitor efficiency of systems and to ensure that their software is complying with the appropriate licenses.

The results of an audit are used to increase the accuracy of the company hardware database, allowing for better support and capacity planning.

Many companies use external auditors to minimise the chance of internal fraud, but some companies do internal auditing for the sake of cost. An audit of financial records is required every year under law (for registered companies).

Audits may also cover the accuracy of systems, especially financial systems. There are three type of auditing techniques, where the auditor calculates by hand the expected output of a system and checks that it matches.

 * Live data testing - where the auditor uses the actual data the system is figuring at this time. This has the disadvantage of being unable to check all possible data types.
 * Historical data testing - in this situation, the auditor puts old data through the system again, so in addition to the manual checks the auditor can check the system agrees with itself both times.
 * Dummy data testing - here, the auditor generates fake data that can test all eventualities

This kind of auditing has the problem of whilst the system is being made available to the auditor, it can not be used for its normal functions, and it only provides a snapshot of the system at that moment in time.

Audit trails
An audit trail is a log created by a system that shows what's been changed and who did what. (The Mediawiki has a great example of this, see the history page for this page, for example.)

Threats to security and integrity

 * Human error (mistakes in data entry, program errors, operator errors)
 * Computer crime (Hacking, illegal modification of data, virii and logic bombs)
 * Natural disasters (Fire, earthquake, hurricane, flood)
 * War and terrorist activity (Bombs, fire)
 * Hardware failure (power failure, disk head crash, network failure)

Building security tends to protect the premises against break-in, unauthorised visitors, etc.

Authorisation software involves user ID's and passwords. It forces a user to log in to access their computer and network, and can enforce "access rights", limiting rights to certain files and folders.

Communications security can use call back (when triggered, dials you, instead of you dialling in – confirms your identity), handshaking (a predetermined exchange between two computers, often following an algorithm) and encryption – altering text by a set algorithm only known by the two communicating systems.

Operational security involves using logs to show usage of the system and creating an audit trail.

Personnel security is necessary because personnel are often the most exploitable part of an IS. Basic user knowledge on security is required in order to prevent access using “social engineering”. Unmotivated employees may also become destructive to company data. By splitting the tasks in a transaction so multiple people are required to be involved, this reduces fraud.

Risk analysis
This is part of the overall corporate ICT security policy, and is something which managers, rather than technical staff need to do. The risk analysis could include finding answers to questions such as:

 * What is the nature of the data being stored in the system?
 * How is the data used?
 * Who has access to the system?
 * How much money does the company stand to lose if the data is lost, corrupted or stolen?

Disaster planning
Disaster (see natural disaster) planning generally only concerns the mission-critical aspects of the business, with less vital functions generally being too costly.

To guard against the failure of a business in a catastrophe, two “controls of last resort” can be put in place – insurance and a disaster recovery plan. Insurance is not a prevention method, but it does help to reduce the financial impact of loss.

A disaster recovery plan has to contain provision for backup facilities which can be used in the event of a disaster. Some possibilities are:

 * A company owned backup facility, geographically diverse – sometimes known as a “cold standby” site.
 * A reciprocal arrangement with another company that runs a compatible computer system.
 * A subscription to a disaster recovery service.

How do you select an appropriate recovery plan? Various criteria are used:

 * The scale of the organisation and its ICT systems
 * The nature of the operation: an on-line system may need to be restored within a few hours, whereas a batch billing process could survive being offline for a few days.
 * The relative costs of the different options: a company with several sites linked by telecoms may be able to formulate a DRP which temporarily moves operations to an alternate site.
 * The perceived chance of disaster occurring. A company in Intake may need a plan to cope with theft, but not with earthquakes.

Legislation
We've already touched on the legislature covering ICT in ICT1. For ICT4, you'll need to be able to recall the Data Protection Act, the Copyright, Designs and Patent Act, the Computer Misuse Act and the Health and Safety Act. When designing a corporate IS strategy, the company should ensure that it complies with the relevant legislature.


text:
Electronics/Steady State

Steady State
That can be said to be the condition of "rest", after all the changes/alterations were made. This may imply, for examples, that nothing at all happens, or that a "steady" current flows, or that a circuit has "settled down" to final values - that is until the next disturbance occurs.

If the input signal is not time invariant, say if is a sinusoid, the steady state will not be invariant either. The response of a systematic convergence can be considered to be composed of a transient response: the response to a disturbance, and the steady state response, in the absence of disturbance.

The transient part of the response tends to zero as time since a disturbance tends to infinity, so the steady state can be considered to be the response remaining as T -> infinity.

. In this case we make an assumption for error we can determine by calculation the extent of statistics how much power there is according to the formulae. Deducing the theory of certain parts of a sinuous making plausible solution in understanding the intricate mechanism of a steady state solution.

title: Electronics/Steady State


text:
AQA Information and Communication Technology/ICT4/User Support

User support is now a crucial part of most commercial packages available today. As software becomes more and more complex, users require support in order to use the software.

A good level of support will cost the company more money, but this can be passed on in either the purchase costs, or in a yearly subscription. However, the company's reputation will improve if it has a reputation for good support.

Support comes in various forms.

Help desk
A help desk is a form of expert system, or knowledge base. It contains a clever search system, and users can also browse categories to see if their problem has been documented. All common problems, and a lot of not-so-common problems are documented on a help desk.

Technical support line
This is a telephone support line manned by real people, who normally access a knowledge base and walk people through procedures.

Technical support lines are often manned by experts who may have difficulty communicating with managers and business users.

On-screen help
This is normally context sensitive. For example, pressing F1 will bring up the help screen for the task you're currently attempting to perform.

Also, on-screen tutorials and wizards exist to make the package easier to use by walking the user through tasks.

On-site support
This is where the developers attend on-site to assist people with their software installations. This only typically happens with large/complex orders, or with custom software, as the cost of such support is very high.

Patches/bug fixes
If a company discovers a bug in their software, they may release a patch that fixes that image. Patches are typically distributed over the Internet, or on CD-ROM from a technical support line.

Peer support
This is where usergroups exist (mainly on forums or Usenet) who help people with problems.

BBS
This is an area of the Internet where files and upgrades to items are shared, there are typically also message boards here where peer support and also technical support takes place

Mailing lists
Similar to a message board, if you subscribe to a mailing list, then you receive a copy of all e-mails sent to it.

Documentation
There are different levels of documentation for different levels of user. This is typically paper or PDF based.

 * Installation documentation
 * System documentation (explanation on dataflows, database schema, etc.)
 * Software documentation (how to use specific features)
 * Operational documentation (day-to-day running of the system)

Training
A company needs well-trained employees who can execute their job efficiently. Training can either be for new employees (induction training) or existing employees (if jobs change, there's new technology or new procedures).

Well trained employees are more likely to get promoted (and are therefore better motivated) and have a better-defined career path. Training can lead to:

 * Increased sales
 * Better service
 * Better products
 * Better safety
 * Lower staff turnover

Different levels of users need different levels of training (workers, middle management, senior management, etc.).

Senior managers who understand ICT are more likely to make better informed decisions than their less well informed colleagues on matters such as the corporate IS strategy.

Middle managers need to ensure that IT systems are used efficiently, and also implement the IS strategy.

For workers, the level of training depnds on their level of responsibility and skill. They can use

 * skills-based training, for developing general IT skills
 * task-based training, for things specific to the IS employed

Even experienced users need to learn new skills if the system changes, so skill-refreshing is also an important part.

There are two main training methods:

 * 1) Computer based - this it is often very cost effective for large groups of people and ensures a consistent standard of training. Users can also work at their own pace and when work is slow.
 * 2) Instructor based - delivered by experienced instructors and has a personal touch, meaning people are more motivated.

There are other training methods, mainly:

 * Video training
 * Interactive video training
 * On line tutorials
 * Step by step guides


text:
AQA Information and Communication Technology/ICT4/Project Management

A project is a set of activities with a defined goals that comes to an end at some point. That is, a project has finite length. A typical project team will comprise individuals with different skills and experience.

A projects will have one or more of the following characteristics:

 * Specified objectives
 * Specific budgets
 * Specified schedule
 * Temporary teams

Projects are lead by the project manager. The project manager does not need any technical skills as their role is to plan and manage the activities the technical specialists on the team must perform, not to perform this work themselves. However, it is normal for a project manager to have at least some background in the technical areas as this makes their job easier. The project manager plans the project, identifies and manages risks, issues and changes, assembles the team and ensures they are engaged on the right activities. The project manager monitors and controls project progress and reports the status to the sponsors of the project. The project manager sometimes controls budgets, prepares performance appraisals and acts as an intermediary between the users, the managers and the developers. In some cases the project team will have a line manager who is not the project manager - the project manager having only matrix responsibility for them. In these cases the project manager would not prepare performance appraisals.

The project manager assembles the development team and has to balance the size. Small teams have shorter lines of communication, are more agile and easier to manage. Larger teams can deliver more work at the cost of a higher management overhead and greater communication problems. These communication problems can lead to serious problems where different parts of the team are not fully synchronised.

The characteristics of a good team are:

 * The leadership provides inspiration and motivation
 * Tasks are allocated well (the best person for each job)
 * Standards are set and observed (procedures, documentation, etc.)
 * The costs, schedules and progression of the project are monitored and controlled.

The project plan should cover a task definition (what needs to be done), skill identification (who can do it) and training (who needs to be able to do what).


text:
AQA Information and Communication Technology/ICT4/Information and the Professional

ICT professionals should act ethically.

(That means no stealing software or hacking people, guys!)

Codes of practice and conduct
This is defined by AQA after they contradicted themselves in previous specifications, so you're best referring there. (Can't copy the content due to their copyright restrictions).


text:
AQA Information and Communication Technology/ICT1

/10.1 Knowledge, Information and Data/


text:
Radiation Oncology/Breast

 * Official Guidelines
 * Staging
 * Breast overview
 * Breast cancer prevention
 * Benign breast diseases
 * DCIS
 * LCIS
 * Paget's Disease
 * Phyllodes tumor
 * Early stage
 * Management of the breast
 * Post mastectomy radiation
 * Management of the regional lymphatics
 * Radiation technique
 * Partial breast irradiation
 * Advanced stage
 * Inflammatory
 * Occult breast primary
 * Breast cancer in pregnancy
 * Breast cancer in men
 * Hormonal therapy
 * Chemotherapy
 * Recurrence
 * Metastatic Disease
 * Toxicity of RT
 * Level I Evidence

See also:
 * Breast sarcoma

Clinical trial listing:
 * NSABP trials

title: Radiation Oncology/Breast


text:
Radiation Oncology/NSABP

The National Surgical Adjuvant Breast and Bowel Project (NSABP): See the NSABP web page.

 * Breast NSABP
 * Colon NSABP
 * Rectum NSABP

NSABP "P" trials (prevention trials) are listed under their respective sites.

title: Radiation Oncology/NSABP


text:
Talk:Basic Geology

I'd like to offer my help with this and possibly any other 'school of geology' stuff. currently a student studying environmental geo. have basic texts books on hand!

Geology Dictionary
I have started a Geology Dictionary. Hopefully this will eventually provide a much needed quick reference for the understanding of gelogical jargon.Hamsterlopithecus (talk) 21:09, 22 October 2009 (UTC)

What is Throw? Hanuman Shukla (discuss • contribs) 15:43, 28 October 2017 (UTC)

title: Talk:Basic Geology


text:
Talk:Seven Habits Study Guide

I say we merge "Private victory" and "Public victory" into the overview. There's a great deal of redundant information between them, and I really can't imagine any good reason to keep them separate. Though it might be nice to have a quick summary one place and a detailed elucidation elsewhere, the separate pages we have now are almost identical. Besides, there's already a "Quick Sheet" on the overview, complete with one-sentence explanations of each step, and our current overview isn't yet large enough to require separate summaries.

Also, unless we decide against my recommendation and instead make the separate overviews noticeably different in scope, we should probably rename the overview page from "Quick overview of the seven habits" to "Overview of the seven habits". An overview is brief by definition, and I don't think what we have qualifies as a brief overview anymore — certainly not in comparison to the other, split summary.

— Elembis 03:52, 21 Jun 2005 (UTC)

Thanks for your effort on this wikibook. Please keep up the good work. I will be sure to come back for more. 213.112.182.70 10:25, 10 May 2006 (UTC)

Practical Application (and I'm a newbie)
I've skimmed the currently written sections of this wikibook, and being someone who had some trouble fully applying the principles in a coordinated way, should we perhaps add comments about how to "personalize" the approach so it works for you? I think I'm finally starting to get it, but I'm sure others would have found it easy to "give up" at some point rather than sticking with it until they found a way for it to work. I strongly think one of us should either create a new section, or put into one of the sections something about how to personalize. For example, I had to do something more intense than just apply Habits 4, 5, and 6 to get the interpersonal "sharpening the saw"; I needed to have at least a few relationships with people that met certain criteria for me, what I consider "close friendships," in order to effectively not go insane :-). The thing is it took me 2 years after seriously trying to apply the 7 Habits to figure this out!  This happened during a time in my life where I did not have friends of sufficient closeness for a long period enough period of time that I noticed how essential they are, at least for me.  I'm sure other people may have similar-type problems in other areas that interfere with their ability to apply the principles in Covey's book.  I think addressing this in some way for a "study guide" would be helpful.

Also, some people I've talked to after they read the book still had the perspective of "quick fix," in applying Covey's principles, rather than the non-quick fix nature of these principles he is attempting to promote. This is despite the fact that they could repeat back to me that Covey is trying to communicate that they are inviolable principles. Perhaps something can be added for this as well? I'm rather new to wikibooks, and trying to think through how I should edit them. (is there a guide for this?) - Gabriel Koulikov 07:15, 29 July 2006 (UTC)

Complicated
I do feel Covey's book is complicated and is in need of reorganization and prioritisation of topics. I strongly feel that success books should NOT have stories of people -- that's hardly useful. What matters are the principles. You want to tell me how John succeeded at tennis? Fine, write the techniques or attitudes rather than the whole story! - Anonymous

I can see why you wouldn't want to have to read stories to learn a new concept. However there is a variety of learning styles. Not all people can grasp a concept unless given examples, often anecdotal, that illustrate those concepts. Reading stories that illustrate concepts in different ways, also reinforces learning, and helps some people to learn more deeply and better retain information. - Terence Wight 14:12, 2 May 2011 (UTC-5)

title: Talk:Seven Habits Study Guide


text:
Consciousness Studies

Consciousness studies embraces the neuroscience and philosophy of consciousness.

Introduction

 * /Introduction/
 * A note on Naive Realism
 * Intended audience and how to read this book

Part I: Historical review

 * /Early Ideas/
 * /Medieval Concepts/
 * /Seventeenth And Eighteenth Century Philosophy/
 * /Nineteenth To Twenty First Century Philosophy/

Part II: The problem of consciousness

 * What needs to be explained: the description and definition of phenomenal consciousness
 * The conflict - where, when and what?
 * The regression argument
 * The subject-object paradox
 * The homunculus argument
 * Phenomenal consciousness and access consciousness
 * Direct Realism
 * Indirect Realism
 * Dualism
 * Idealism
 * Panpsychism
 * Breaking down the philosophical and scientific problems
 * The philosophical problem of phenomenal consciousness
 * Epiphenomenalism and the problem of change
 * The problem of time
 * The problem of space
 * The problem of qualia
 * Elementary Information and Information Systems Theory
 * Classification, signs, sense, relations, supervenience etc.
 * Qualia and Information
 * Absent and fading qualia
 * Putnam's twin earth thought experiment
 * The Inverted Qualia Argument
 * The Knowledge Argument
 * The problem of machine and digital consciousness
 * Measurement in physics and the preferred basis problem

Part III: Neuroscience of consciousness

 * The neuroscience of consciousness
 * Introduction
 * The substrate of experience
 * Neuroanatomy
 * Topological mapping and cortical columns
 * The neurophysiology of sensation and perception
 * Vision
 * Depth perception
 * The cortex and thalamus
 * The cortex and consciousness
 * Perception, Imagination, Memory and Dreams
 * More about Models
 * Blindsight
 * The Role of the Thalamus
 * General Anaesthesia and the Thalamus
 * The function of consciousness
 * Perceptual "filling in"
 * Rivalries and synchronisation
 * Binocular Rivalry, Pattern Rivalry and Binocular Fusion
 * Synchronisation of Neural Processes
 * EEG and synchronisation
 * Event related potentials
 * The integration delay
 * Global Workspace Theory
 * The "cognitive map" and the neural basis of perceptual space
 * /Behaviourism And Consciousness/
 * /Models Of Access Consciousness/
 * Neural networks
 * Quantum information processing

Part IV: Explanations of Consciousness

 * Contemporary explanations of consciousness
 * The identity theory of mind
 * Scientific theories
 * Functionalism
 * Dualism
 * Intentionalism
 * Higher order thought
 * Eliminativism
 * Mysterianism
 * Idealism and panpsychism
 * Other explanations of consciousness
 * Consciousness-only
 * BioPsychoSociology Model 1 BPS Model

Appendices
Some physical science for consciousness studies:
 * Ontology of Newtonian physics: kinetic energy and magnetism
 * The origin of the metric tensor
 * Action, Lagrangian and Hamiltonian Mechanics
 * /Index/
 * /Notes for the Contributors/
 * /Contributors/

Études sur la conscience Sąmonė

title: Consciousness Studies


text:
Consciousness Studies/The Neuroscience Of Consciousness

"All parts of the brain may well be involved in normal conscious processes but the indispensable substratum of consciousness lies outside the cerebral cortex, probably in the diencephalon" Penfield 1937.

"The brain stem-thalamocortical axis supports the state, but not the detailed contents of consciousness, which are produced by cortex" Baars et al 1998.

Introduction
It is recommended that readers review ../The Philosophical Problem/ before reading the sections on the neuroscience of consciousness.

One of the most exciting discoveries of neuroscience is that nearly all of the brain performs functions that are not part of conscious experience. In everyday life we are usually unaware of breathing or heartbeats yet there are parts of the brain dedicated to these functions. When we pick up a pencil we have no experience of the fine control of individual muscles yet large areas of cortex and cerebellum implement this. Things do not appear as greyscale and then have the colour poured into them although this strange colour addition is done in the visual cortex. Most of the brain is non-conscious but how is the "ghost in the machine", the mind, created by and linked into the mostly non-conscious brain?

Although most of the processes in the brain are non-conscious there can be little doubt that the output of sensory processes contribute to experience. For example, although we do not experience the process of adding colour to visual data in cortical area V4 we do experience coloured forms and although we have little inkling of the hugely complex creation of words in the temporal/frontal lobes we do experience verbal thoughts. Our experience is an integrated output of most of the brain processes that deal with sensation as well as dreams, thoughts and emotions. But how and where does this experience occur?

The signals that compose phenomenal consciousness have not been elucidated. Perhaps the least likely signals for this role are electrical impulses in nerve fibres because they are distributed unevenly in time and space and can even be absent for relatively long periods. Furthermore, electrical impulses across the membranes of neurons have an all or nothing character; they cannot be easily superimposed on one another. There are many other possibilities however, such as: the electrical fields on the dendrites of neurons, the fields of chemicals spreading out from synapses, the radio-frequency emissions of action potentials, events in the microtubules in cells, the depolarisations of glia, the varying fields measured by EEG devices, the quantum superposition of brain states etc...

Phenomenal consciousness could exist in the dendritic field of ten neurons receiving 100,000 synapses or as an oscillation of fields over the whole brain. The substrate of phenomenal consciousness could be staring us in the face as a state of the whole brain or be like a needle in a haystack, lurking in a tiny region of brain, unsuspected and undiscovered.

Given that there is no widely accepted theory of phenomenal consciousness Crick (1994) and Crick and Koch (1998) approached the problem of the location of the substrate of consciousness by proposing that scientists search for the Neural Correlates of Consciousness. These neural correlates consist of events in the brain that accompany events in conscious experience.

References:

Crick, F. (1994). The Astonishing Hypothesis. New York: Scribners.

Crick, F. & Koch, C. (1998).Consciousness and Neuroscience. Cerebral Cortex, 8:97-107, 1998 http://www.klab.caltech.edu/~koch/crick-koch-cc-97.html

General layout of the CNS
The Central Nervous System (CNS) consists of the spinal cord, the brain and the retina.

The CNS consists of two major groups of active cells, the neurons and the glia. The neurons conduct short impulses of electricity along their membranes called 'action potentials and encode data as frequency modulated signals (i.e.: different intensities of stimulation are converted into different rates of firing). The glia modify the connections between neurons and can respond to neuron activity by a change of voltage across their membranes. Glia also have many other roles such as sustaining neurons and providing electrical insulation.

Neurons have three principal parts: the cell body, the dendrites and the axon. Impulses flow from the cell body to the axon. The axon can be over a metre long and bundles of axons form nerve fibres. Where an axon makes contact with the dendrites or cell body of another neuron there is a special sort of junction called a synapse. Transmission of data across synapses is usually mediated by chemical signals.

Areas of the brain where there are many cell bodies have a beige/grey tinge and are called grey matter. Areas that contain mainly nerve fibres are called white matter. Masses of grey matter outside of the surface of the cerebral cortex or the cerebellum are called nuclei.

The brain is of central interest in consciousness studies because consciousness persists even when the spinal cord is sectioned at the neck.

The brain can be divided into five distinct divisions or vesicles on the basis of embryological development. These are the myelencephalon, metencephalon, mesencephalon, diencephalon and telencephalon (See the illustration below).

 * Myelencephalon: Medulla oblongata.
 * Metencephalon: pons and cerebellum.
 * Mesencephalon: midbrain (tectum containing the superior colliculus and inferior colliculus, red nucleus, substantia nigra, cerebellar peduncles.
 * Diencephalon: thalamus, epithalamus, hypothalamus, subthalamus.
 * Telencephalon: corpus striatum, cerebral hemispheres.

These divisions tend to obscure the physical anatomy of the brain which looks like a rod of spinal cord with a swelling at the top due to the thalamus and corpus striatum. Around the top of the rod is a globe of deeply indented cerebral cortex and at the back there is the puckered mass of cerebellum. The physical anatomy is shown in greater detail in the illustration below where the thalamus and corpus striatum have been splayed out to show more detail.

The thalamus is a complex organ with numerous nuclei. These are listed below:

The location of these nuclei is shown in the illustration below:

The cerebral hemispheres consist of a thin layer of nerve cell bodies on the surface (the cerebral cortex) with a mass of white, interconnecting fibres below (the cerebral medulla). Each hemisphere is divided into four principle lobes as shown in the illustration below:

The cortex is a set of interconnected processors. The general layout of the cortex with the location of the processors is shown in the illustration below:

The pathways in the brain tend to preserve the topography of the sense organs so that particular groups of cells on the retina, cochlear or body have corresponding groups of cells in the thalamus or cortex. The retina is said to have a topological mapping onto the thalamus so that the projection of the optic nerve is said to be retinotopic.

Nerve fibres that go to a part of the brain are called afferents and fibres that come from a part of the brain are called efferents.

The cortex and thalamus/striatum are intimately linked by millions of connecting fibres and there is also a direct connection from the motor cortex to the spinal cord.

Sensory pathways
Information from the sense organs travels along the appropriate sensory nerve (optic, auditory, spinal etc.) and once in the brain is divided into three principal paths that connect either with the thalamus, the cerebellum or the reticular formation.

There are thalamic nuclei for each broad type of sensation and these have reciprocal connections with specific areas of cortex that deal with the appropriate mode of sensation. The large mass of nerve fibres that mediate the connection between the thalamus and cortex are known as the thalamo-cortical and cortico-thalamic tracts. There tend to be more sensory nerve fibres returning from the cortex to the thalamus than connect from the thalamus to the cortex so it is difficult to determine whether the cortex is the destination of sensory data or a region that supplies extra processing power to thalamic nuclei.

The cerebellum mediates reflex control of complex movements and receives input from most of the sense organs.

The reticular formation is a group of loosely distributed neurons in the medulla, pons and mesencephalon. It receives a large amount of autonomic input and also input from all the sense organs. The intralaminar nuclei of the thalamus are the principal destination of reticular output to higher centres. In the most primitive vertebrates the reticular formation performs most of the higher control functions of the animal. The reticular formation is implicated in the maintenance of sleep-wake cycles and activates the higher centres. This activity has attracted the label ascending reticular activating system (ARAS) to describe how the activity of higher centres is controlled by reticular input. This title is unfortunate from the point of view of consciousness studies because it implies that conscious experience is a result of activating the cortex when it could be due to turning on or off particular systems all the way from the reticular formation to the cortex. Destruction of the reticular formation leads to coma.

Motor and output pathways
Motor control of the body below the skull is accomplished by three principle routes.

The motor cortex of the frontal lobes and related cortex in the parietal lobes can control movement directly via nerves known as the cortico-spinal tract (also called the pyramidal tract). The activity of the motor cortex is modified and controlled by a loop that passes through the corpus striatum, the substantia nigra and the subthalamic nucleus and returns to the cortex. These controlling nuclei are, along with the amygdala, known as the basal ganglia.

The cerebellum and the corpus striatum provide complex reflex control of the body through nerves that travel through the red nucleus and form the rubro-spinal tract.

The vestibular nucleus, which processes signals related to balance and posture, has direct connections with the periphery via the vestibulo-spinal tract.

Apart from the routes for controlling motor activity there are also other outputs from the brain, for instance the autonomic nervous system is intimately linked with the reticular formation which has areas that control blood pressure, respiratory rhythm etc.

Topological mapping and cortical columns
The cerebral cortex has a highly convoluted surface that provides a large area of tissue. The parts of the cortex that are used for motor and sensory functions are organised so that different areas correspond to different zones of the body. This topological organisation is shown classically by a drawing of the sensorimotor homunculus such as that shown on the right.

Within a given area of the cortex there are further subdivisions. For example, the occipital cortex corresponds to the eyes of the sensorimotor homunculus and it is further organised so that areas of the retina have corresponding areas on the cortex. This mapping of the layout of the retina onto the cortex is known as topological mapping. It results in a corresponding mapping of the receptive field of the eye onto the cortex. The mapping is like an image on the surface of the brain tissue and the visual scene that is presented to a subject can be recovered by using fMRI along with computer analysis (Miyawaki et al. 2008).

The human cortex is fairly deep, containing 100-200 neurons from the surface to the white matter. It is divided into six histological and functional layers. These layers can be further subdivided. In 1957 Mountcastle used microelectrode measurements to show that activity of small zones of cortex about 0.1 to 1 mm in diameter corresponded to particular points in the receptive field. These functional columns of cortical tissue are called cortical columns.

The diagram above shows the organisation of ocular dominance columns. Each column represents a particular part of the receptive field of a single eye. The columns for left and right eyes are linked together in lines. The lines of ocular dominance form a pattern like a fingerprint on the surface of the cortex.

The same part of cortex can have overlapping columns for different functions. For instance there are columns that react to particular orientations of edges at particular places in the visual field. These columns tend to be located together on the cortex forming a pinwheel of columns that cover all orientations at a particular receptive field position.

There are also topologically arranged columns for colour, spatial frequency etc.

Yoichi Miyawaki, Hajime Uchida, Okito Yamashita, Masa-aki Sato, Yusuke Morito, Hiroki C. Tanabe, Norihiro Sadato and Yukiyasu Kamitani. (2008). Visual Image Reconstruction from Human Brain Activity using a Combination of Multiscale Local Image Decoders. Neuron, Volume 60, Issue 5, 10 December 2008, Pages 915-929

Modules
 * The neurophysiology of sensation and perception
 * The cortex and thalamus
 * Rivalries and synchronisation


text:
Consciousness Studies/Neuroscience 1

The cortex and consciousness
The cerebral cortex consists of a set of specialised areas that process different aspects of sensation and motor control. There are about ten times as many nerve fibres going from the cortex to the thalamus as there are from the thalamus to the cortex (Destexhe 2000).

Histologically the cerebral cortex is a layer of greyish neurons overlying a huge mass of white nerve fibres, the cerebral medulla. The cortex consists of six main layers. The upper layers receive input from the relays in the thalamus such as the lateral geniculate, from the thalamus in general and from other areas of cortex plus a few specialised inputs from other locations. The lower layers give rise to output fibres that largely connect with the thalamus and other areas of cortex although particular specialised processors in the cortex may also have direct connections elsewhere such as to motor nuclei.

The cerebral cortex has many functions and is divided up into numerous separate processors. The most important function of the cortex from the point of view of consciousness studies is that it creates models. As was seen in Part I, philosophers debate whether these models are actually experienced consciously but in the neurophysiological literature it is normally assumed that we do experience models and rehearsals such as inner speech and imaginings. There is considerable evidence that the parts of the brain that deal with imagining (modelling) things are also the parts that deal with perception (i.e.: modelling the world). The overlap between imagination and normal perception is not complete because, as Tong(2003), in a review of visual consciousness, put it: "Internally generated experiences share some, but not all, of the phenomenal properties of actual perception". There is also considerable overlap between the areas used for imaginary speech (thought) and actual speech, areas dealing with the control of sensation and of the tongue etc. being used in actual speech but not in imagined speech (Fu et al. 2002). Kreiman et al. (2000) investigated the activity of single neurons in humans and also found that the brain activity evoked by visual imagination overlapped that which occurs upon direct stimulation by the same image.

Our conscious experience consists of the output of the cortical modelling and perceptual processes. The cerebral cortex itself appears to be non-conscious. The evidence for the non-conscious nature of the cerebral cortex consists of lesion studies in which large amounts of cortex can be removed without removing consciousness and physiological studies in which it is demonstrated that the cerebral cortex can be active without conscious experience.

Lesion studies have shown that up to 60% of the cerebral cortex can be removed without abolishing consciousness (Austin and Grant 1958). An entire hemisphere can be removed or much of the front or back of the cerebral cortex can be cut off yet consciousness persists.

Fiset et al. (1999) and Cariani (2000) have shown that cortical activity can be normal or even elevated during the unconscious state of general anaesthesia. Alkire et al. (1996) also showed that cortical activity related to word recognition occurred during general anaesthesia.

Libet et al. (1967) found that there could be cerebral cortical activity in response to weak stimulation of the skin without any conscious awareness of the stimulus. This work provides a neurophysiological basis for subliminal (non-conscious) perception and also shows that large areas of the cerebral cortex can be active without conscious experience. The insensitivity of experience to cortical activity has been further confirmed by Libet et al. (1979). They electrically stimulated the cerebral cortex of conscious patients and discovered that the stimulus must be continued for about 0.5 seconds for subjects to report a conscious experience of the stimulation. Libet's findings have been analysed at length but there still appears to be a 0.25 to 0.5 secs delay (Klein 2002).

It has been demonstrated that cerebral cortical activity is not synonymous with conscious experience but why should there be a delay of up to 0.5 seconds or so between cortical stimulation and a conscious percept? What is the cortex doing in the 0.5 seconds between the start of stimulation and the report of awareness of the stimulation? It is probably synchronising its various processors and creating a waking dream, a structured set of events that accounts for the activity. The synchronisation of cerebral cortical processes will be discussed later, but what evidence is there for the cerebral cortex constructing a waking dream, or model, to describe the world?

The 'Attentional Blink' (Raymond et al. 1992) is consistent with the concept of the cerebral cortex being a device that creates models. In the 'Attentional Blink' the identification of an object impairs the identification of a second object that is presented within 0.5 seconds of the first. Raymond et al. used a stream of letters (11 letters per second) and the identification of a first letter impaired the identification of a subsequent 'probe' letter in the stream. If the probe letter followed the first letter within about 180 msecs it could easily be identified, suggesting that chunks of about 180 msecs of data stream are modelled together. Christmann & Leuthold (2004) have theorised that the 'Attentional Blink' involves perceptual and central components of visual processing. This is supported by the fMRI studies of Marois et al. (2004) who presented subjects with faces mounted on scenes of places. The scenes of places often went undetected by subjects but they activated regions of the medial temporal cortex involved in high-level scene representations, the parahippocampal place area (PPA). When the scenes of places were detected by the subjects there was activity in the frontal cortex and the PPA activity was increased. These experiments are consistent with the idea of a cerebral cortex that is a multiprocessor system that creates consistent models of the environment.

Bregman's (1990) auditory continuity illusion is another example of how sensory events are modelled. If a pure tone is followed by broadband noise and the noise followed by the same pure tone it seems as if the tone occurs throughout the period of noise. If the noise is not followed by the pure tone there is no sound of the tone during the period of noise. This effect is similar to the results found by Libet because a delay of several hundred milliseconds between sensory stimulation and conscious experience is needed to account for the apparent rewriting of history after the second tone appears.

Dennett and Kinsbourne (1992) argued strongly against modelling as the source of conscious experience. They discussed two illusions, the "cutaneous rabbit illusion", in which the subject is tapped successively in such a way that some illusory taps appear and the "phi illusion" in which successively illuminated lights appear as a motion of the light. Dennett and Kinsbourne declared that there should be no cerebral cortical filling in of the gaps in the these illusions. Both these illusions have now been investigated. Blankenburg et al. (2006) found that cerebral cortical activity occurred at the locations expected for the missing taps in the "cutaneous rabbit" illusion and Larsen et al. (2006) found that the areas of cerebral cortex that would be stimulated by a moving light were active during the "phi illusion".

The delay before consciousness of "voluntary" actions
The 0.5 second delay required for the cortex to model an event has implications for the role of conscious experience in the control of our lives. If experience is about 0.5 seconds behind the true present instant then how can we be said to control anything? The brain must be acting automatically whilst performing most tasks. The 0.5 second delay also seems to contradict our everyday experience. We certainly feel like we are aware of things in less than 0.5 seconds, for example, the direct stimulation of sense organs seems to be experienced much more rapidly than the delayed experience of cortical stimulation. In fact subjects report that they are conscious of stimuli, such as being touched or seeing flashing lights, within 0.1 to 0.2 seconds of the event. So how can subjects report events within 0.2 seconds even though it seems to take 0.5 seconds for the cortex to generate activity that can be experienced? The simplest explanation is that the reaction occurs automatically within 0.2 seconds and then the conscious experience of this reaction occurs 0.3 seconds later. This gives a total 0.5 seconds delay before conscious experience whilst allowing fast reactions.

Libet et al. extended their experiments by stimulating a "relay nucleus" in the thalamus that intercepts signals from the senses before they reach the somatosensory cortex. It was found that when this nucleus was stimulated for 0.5 seconds the subjects reported that the stimulus occurred 0.2 seconds after it had begun. When the nucleus was stimulated for less than 0.5 seconds the subjects did not report any sensation. This supports the concept of a 0.5 second delay whilst the cortex puts a stimulus in context before it is experienced.

These experiments show that our experience is an output of cortical processing rather than the processing itself. If our conscious experience is non-cortical then this raises the possibility that the non-conscious cerebral cortex can perform actions without conscious control. Of course, the cortex does this all the time when we are indulging in skilled or routine behaviour. The ability of the non-conscious cortex is quite remarkable; for instance car drivers sometimes discover that they have driven for several miles without conscious experience of driving, even at the level of having no recollection of the route.

Although it might be accepted that much of our everyday behaviour is automatic is there any behaviour that is definitely initiated by conscious experience? This is probably a pointless question because consciousness is about observation, not action; however, despite this there have been several experiments that have attempted to determine the relationship between consciousness and action.

In 1964 Kornhuber and Deecke performed a series of experiments that measured the electrical activity from the scalp (EEG) during voluntary actions. They averaged many EEG's from subjects who were about to move a finger and discovered that there is an increase in scalp potential before the movement takes place. The increase in potential can start as long as 2 seconds or so before the movement and is known as the "readiness potential" (Bereitschaftspotential). The readiness potential is strange because it seems to contradict our conscious experience; we do not decide to move a hand and then wait 2 seconds before the hand moves. It seems that the non-conscious brain may be taking things into its own hands.

Libet et al. (1983) extended the readiness potential experiments by asking subjects to observe a Wundt clock whilst flexing a finger. The Wundt clock had a spot of light that moved around a circle every 2.56 seconds and allowed the subjects to obtain timings that were related to their mental experiences. When the subjects flexed a finger it was found that the readiness potential occurred about 0.5 seconds before the finger moved and the subjects reported they were going to move the finger about 0.2 seconds before the movement. This suggested that a subject's cerebral cortex was preparing for the movement about 0.3 seconds before the subject was conscious of this. Libet's experiments have been reproduced elsewhere (see Keller & Heckhausen 1990). (It is important to note that the subjects in Libet's experiment were asked to wait until they felt the urge to move the finger.) These results are consistent with the idea of the cortex as a modelling system that constructs a consistent model of events to pass on to whatever mediates conscious experience.

More recently fMRI and direct electrode recording have borne out the readiness potential experiments. Soon et al. (2008) allowed subjects to decide to press either a left or right button. They used fMRI to show that there was spatially organised activity in the polar frontal cortex and parietal cortex (from precuneus into posterior cingulate cortex) that predicted the conscious left/right decision and preceded it by about seven seconds. Rektor et al. (2001) used direct electrode recordings to show a 2 second latency. Haggard & Eimer (1999) and also Trevena and Miller (2002, 2009) have identified a "Lateralized Readiness Potential" that is correlated with the movement of a particular hand (left or right) in their EEG experiments and Trevena and Miller claim that this potential always follows the making of a conscious decision and precedes the actions being studied. However, Soon et al. (2008) showed that fMRI can predict which button will be used well before any conscious decision is reported. (See Haggard (2008) for a review of conscious volition).

More about Models
Our dreams are clearly models that form a 'dreamworld' but the idea that perception might be like a dream that is updated by sensation is not so obvious. Experience seems to be an active model of the world (virtual reality) based on sense data rather than a simple mapping of retinal and other sensory data. This is demonstrated by visual illusions such as the Ames Room, Spoke Illusion and Muller Lyer illusions shown below:

Notice how the circle is distorted without any distortion in the 'spokes', it is as if the circle has been treated as a separate object by the processes in the brain that rearranged it. In all of these illusions the brain has rearranged large areas of the visual field and has managed the input as a collection of 'objects' that are manipulated separately. Even movement seems to occur in some figures showing that the brain models the position of things:

The creation of a model is also demonstrated by the illusion of movement experienced when we watch the cinema or television. This is due to the cortical modelling that is known as 'short-range apparent motion' rather than flicker fusion or persistence of vision. It is intriguing that, although it has been known for decades that the joining together of static images in our minds is due to modelling activity in the brain the myth that it is due to persistence of vision or flicker fusion is universal. As Anderson and Anderson (1993) noted:

Indeed, in the past decade, psychoanalytic-Marxist film scholars have retained the model implied by persistence of vision: theirs is a passive viewer, a spectator who is "positioned," unwittingly "sutured" into the text, and victimized by excess ideology.

Our experience of the cinema is like a dream updated by sensation rather than sensation updated by interpretation. In fact the most compelling evidence for the modelling power of the brain is the existence of dreams; our dreams are often models of worlds that do not exist and involve little or no sensory input yet can involve effects as powerful as any television drama.

Short range apparent motion occurs when the interval between presentations of an object is brief (c. 50-100 msecs). Motion modelling in response to longer intervals is known as long range apparent motion. There is evidence that the modelling in short range apparent motion is enhanced if the moving patterns are similar to moving human forms (such as patterns of dots outlining a person)(Thornton et al. 1998). The accuracy of predicting movement can actually improve if the interval between presentations is increased when human forms are used.

Motion modelling can also be seen in visual illusions such as the Waterfall Illusion (motion aftereffect). The waterfall illusion is commonly seen after viewing a sequence of scrolling credits on the television; when the credits stop rolling it appears as if they briefly move in the opposite direction. Tootel et al. (1995) have used fMRI to show that this is correlated with activity in the motion modelling area of visual cortex (area MT/V5). The waterfall illusion is also associated with an intriguing aftereffect known as storage of the motion aftereffect. Normal motion aftereffects last for up to about ten seconds after the stimulus, however, if the subjects close their eyes for the normal duration of the aftereffect then reopen them they see the illusion for almost the normal duration. Culham et al. (1999) used fMRI to show that activity in area MT/V5 was low during the period when the eyes were closed then increased dramatically when the eyes were opened. This is strongly suggestive of a modelling mechanism outside MT/V5 that has adapted to motion and then models stationary data with movement in the wrong direction.

Visual area MT/V5 is also involved in the separation of moving visual scenes into sprites or objects that move together as a whole within a scene (Muckli et al. 2002).

The way that mental models may be the basis of ordinary reasoning was outlined by Johnson-Laird (1980), based on earlier work by Kenneth Craik.

Studies of 'change blindness' and 'inattentional blindness', where subjects fail to spot outrageous changes in their environment, also demonstrate that we experience a model and suggest that the brain must analyse an object to incorporate it fully into the model (See for instance Rensink (2000), Simons & Rensink (2005)).

Brain areas used in perception overlap those used in imagination and recall
Functional Magnetic Resonance Imaging (fMRI) has shown that similar areas of brain are used during perception involving the senses as during imagination (Tong 2003, Kosslyn and Thompson 2003). The substrate of the mental images that occur in both modes of brain activity has not yet been found. This overlap of the brain areas used in perception with those used in imagination, memory and recall has been demonstrated in a wide range of experiments.

Ganis et al. (2004) used fairly complex perceptual and imagination tasks that activated large areas of the brain, they found an overlap between the brain areas activated during perception and imagery. The principle areas that were different in the two tasks were found in the primary sensory areas of the visual cortex. Other areas in the visual cortex and activity in the rest of the brain showed a remarkable degree of overlap. The authors suggested that the differences in the activity of primary visual cortex may have been due to differences between the perceptual and imaginary stimuli such as speed of onset etc. The hippocampus was not activated.

It is intriguing that, contrary to object imagery, spatial imagery such as predicting when a cross on a screen would fall on an imaginary letter actually seems to inhibit activity in sensory visual cortex (Aleman et al.). Both fMRI and blocking with transcranial magnetic stimulation (TMS) showed that the posterior parietal cortex was involved in the spatial imagery.

Imagery involving places and faces activates the place and face areas that are activated during perception (Ishai et al. 2000).

The recall and recognition of things also seems to involve very similar brain areas to those used during perception. Wheeler and Buckner (2003) showed that areas involved in perception were also involved in the recall of the perceptual stimuli.

Recall causes activation of areas used in perception but also seems to use areas that may be particularly related to the process of recall iself, such as the left parietal cortex (Konishi et al. 2000) (Brodmann's area 40/39). Frontal and parietal regions are involved in the recognition of whether stimuli have been experienced before.

Image generation during sleep seems to differ from that during imagination and recall. In particular it seems to involve a few well defined areas of cortex and considerable activation of the posterior thalamus.

Sleep studies have shown that people dream throughout sleep. However, dreams are more frequent during the REM (rapid eye movement) periods of sleep than the NREM (non-REM) periods. Dreams are reported after 70-95% of awakenings in REM sleep and 5-10% of awakenings in NREM sleep. REM dreams are more visual than NREM dreams which are more 'thoughtlike' (Solms 2000). Thoughtlike events (mentation) are reported after 43% of awakenings from NREM sleep. Solms (1997) found that patients who had lesions in the parietal-temporo-occipital junction reported a cessation of visual images in dreams. Solms also found that patients with lesions in the white matter inferior to the frontal horns of the lateral ventricles, in the ventromesial quadrant of the frontal lobes, also reported loss of dreaming. Loss of dreaming is also reported by leucotomised patients with frontal ventromesial damage. Damasio et al. (1985) and Solms (1997) also reported that some patients with damage to the medial prefrontal cortex, the anterior cingulate cortex, and the basal forebrain became confused about what was real life and what was dreaming (waking dreams occurred).

Studies using fMRI show that the sensory occipital lobe (BA 18) and posterior thalamus, especially the lateral geniculate nuclei, are activated in REM sleep, weaker activations of the posterior cingulate, putamen and midbrain were also found (Wehrle et al. 2005, Loveblad et al. 1999). These findings are consistent with activation of the ponto-geniculo-occipital system (PGO) during REM.

So dreams may be more like primary activations of sensory cortex than imagining or recall. This suggests that dreams have a thalamic origin or are managed via connections from the cortex through the thalamus to the visual cortex.

Hallucinations seem to differ from dreams. In Charles Bonnett Syndrome patients can have clear hallucinations. These, like imaginations, seem to involve areas of the visual cortex that deal with processed data, for instance hallucinations of faces activate the "face area" rather than visual cortical area V1 (Ffytche et al. 1998).

Suppression of data acquisition during saccades - perception as a patchwork
If you look at yourself in the mirror you will not see your eyes moving even though they will be darting all over the view of your face. Even when you deliberately look from place to place your eyes will appear steady. The natural darting of the eyes from place to place as you view a scene is known as "saccadic" movement of the eyes. The suppression of the visual image during the motion of the eyes is known as "saccadic suppression" or "saccadic masking". The suppression of the acquisition of image data extends to suppression of awareness of flashes of light during saccades, this effect is known as "flash suppression", however, flash suppression seems to apply only to rather dull flashes (Volkman (1962). The suppression during saccades is probably due to suppression of the magnocellular pathway (the motion sensitive pathway) in the lateral geniculate nucleus (Burr et al. (1996).

The most intriguing feature of this suppression of data acquisition during saccades is that each snapshot that is obtained between saccades can only contain a relatively small amount of information. This is because the fovea, which is the most sensitive area of the eye, is tiny (about 1mm diameter) and only receives input from a few degrees of the visual field. As a result what we consider to be a uniform scene in our minds is actually a patchwork of intersaccade snapshots.

Another aspect of saccades is that the timing of events is referred back to the beginning of the saccade. This effect is known as "saccadic chronostasis". For example, if an object changes colour during a saccade the observer feels as if the colour change occurred at the beginning of the saccade, so extending the amount of time that the object possesses the changed colour. This effect can extend apparent durations by up to 500 ms and is consistent with the idea that the visual system models events prior to perception (see Yarrow et al. 2006).

Burr D, Morrone M, Ross J. (1996) Selective suppression of the magnocellular visual pathway during saccades], Behavioral Brain Research 80 1-8 (1996) http://www.pisavisionlab.org/downloads/BBRReview96.pdf

Volkman, F. (1962). Vision during voluntary saccadic eye movements. J. Opt Soc. Am. 52:571-578. 1962.

Yarrow, K, Whiteley, L, Rothwell, J.C & Haggard,P. (2006) Spatial consequences of bridging the saccadic gap. Vision Res. 2006 February; 46(4): 545–555. http://www.hexicon.co.uk/Kielan/papers/Moving_chrono.pdf

Blindsight
Blindsight studies illuminate the relationship between the cerebral cortex and our experience. When the visual cortex is removed subjects become almost totally blind. If the visual cortex on one side is removed subjects become relatively blind in the contra-lateral hemifield. One of the most revealing studies of blindsight is Marcel's 1998 paper: " Blindsight and shape perception: deficit of visual consciousness or visual function?".

It is useful when considering blindsight to contemplate for a while the appearance of the world with both eyes closed and then with one eye closed. When both eyes are closed our experience is of a darkish space radiating out from our heads, with one eye closed we tend to ignore the darkish areas that cannot be seen even though they are still present. Marcel notes that patients who have a right blind field still have an underlying visual field on the right side and that this can even contain conscious visual experience. This sounds a bit like the darkish space that we all experience if deprived of visual input on one side. As Marcel says: "A question that naturally arises is whether the loss is a 'total' loss of visual consciousness in the blind field. It is often assumed to be so, especially by those who discuss blindsight without carefully reading the literature or working with the subjects. One can immediately respond negatively to the question.."

The consciousness of the completion of Kanizsa figures in blindsight patients is particularly indicative of the preservation of the field even though the content was largely missing. A Kanizsa figure is shown below:

If we put Marcel's observations together with cortical anatomy and function it seems that the space of our experience is located outside of the cerebral cortex. The cortex generates much of visual and other content but it does not generate the space.

The Role of the Thalamus
The thalamus is connected to the entire bottom layer of the cerebral cortex. It is the nexus of the various cortical processors as well as a recipient of independent input from most of the rest of the brain.

The thalamus is subdivided into numerous small and medium sized nuclei that between them receive inputs from every process in the nervous system (the white fibres in the illustration above largely penetrate the thalamus). The thalamic nuclei are interconnected which means that any of them could, potentially host activity from anywhere in the body or brain. Although the founders of neurology such as Hughlings Jackson and Penfield & Jasper located conscious experience in the diencephalon, including the thalamus, this is no longer the conventional wisdom. The small size of the thalamic nuclei means that they cannot support the processes that are assumed to compose access consciousness, however, even some of the smallest thalamic nuclei host millions of synapses so size would not be an obstacle if the thalamus contains the substrate of phenomenal consciousness. Indeed, the diencephalon and the thalamus in particular can be shown to be excellent candidates for a possible location of phenomenal experience.

The Intralaminar Nuclei of the thalamus. The white space above and to the left of RN is the third ventricle. MD=mediodorsal nucleus. CM=Centromedian nucleus, RN=red nucleus (not part of thalamus) The black areas are stained white fibres. Picture from: http://www.neurophys.wisc.edu/ University of Wisconsin and Michigan State Comparative Mammalian Brain Collections. Preparation of image has been funded by the National Science Foundation, as well as by the National Institutes of Health. May only be used with these acknowledgements.

If the thalamus contains a location for conscious experience then lesions should abolish this experience. Unlike the cerebral hemispheres, lesions of the thalamus do indeed seem to abolish consciousness. The area that is most sensitive to lesions contains the Intralaminar Nuclei, especially the Parafascicular and Centromedian Nuclei. If these are damaged bilaterally patients suffer death, coma, akinetic mutism, hypersomnia, dementia and other equally serious impairments of consciousness that depend upon the size and placement of the lesions (Bogen 1995, Schiff & Plum 1999). In cases of fatal familial insomnia, in which patients exhibit many of these symptoms, there is marked neuron loss in the Intralaminar Nuclei (Budka 1998).

The effect of interrupting the blood supply to the medial thalamus depends upon the severity of the damage. There is frequently initial coma. The recovery after coma is often incomplete, Krolak-Salmon et al. (2000) described bilateral paramedian thalamic infarcts as normally being "followed by persisting dementia with severe mnemic disturbance, global aspontaneity and apathy." The symptoms of bilateral damage to the ILN can be so severe that it is possible that, even after recovery from coma, some patients may cease to be conscious and are being coordinated by automatic cortical processes.

Bjornstad et al. (2003) and Woernera et al. (2005) both reported that the initial coma after bilateral paramedian infarct was accompanied by a similar pattern of EEG activity to stage 2 sleep. Woernera et al. (2005) also discovered that painful stimuli gave rise to a range of EEG activity, transiently breaking the stage 2 sleep pattern but without recovery of consciousness. Unfortunately even in those patients who recover consciousness Kumral et al. (2001) report that "Cognitive functions in patients with bilateral paramedian infarction did not change significantly during the follow-up, in contrast to those with infarcts in varied arterial territories" although Krolak-Salmon et al. (2000) did report a single patient who made a total recovery.

Laureys et al. (2002) investigated recovery from 'persistent vegetative state' (wakefulness without awareness). They found that overall cortical metabolism remained almost constant during recovery but that the metabolism in the prefrontal and association cortices became correlated with thalamic ILN and precuneus activity. Again confirming that thalamo-cortico-thalamic activity is required for consciousness and that cortical activity by itself is not conscious. Yamamoto et al. (2005) investigated persistent vegetative state and found that deep brain stimulation (25Hz) of the centromedian-parafascicular complex (19 cases) or mesencephalic reticular formation (2 cases) resulted in 8 of the patients emerging from persistent vegetative state. It is interesting that zolpidem, a GABA agonist, has recently been found to reverse PVS in some patients (Claus & Nel 2006). The effect is rapid and might be used to demonstrate the correlations that occur on recovery from PVS.

As Bogen(1995) demonstrates, the ILN receive inputs, either directly or indirectly, from every part of the CNS but what do they do?

Interest in the thalamus has recently been revived by the theories of Newman & Baars (1993), Baars, Newman, & Taylor1998) and Crick & Koch (1990). In Baars, Newman and Taylors' (1998) theory it is suggested that "The brain stem-thalamocortical axis supports the state, but not the detailed contents of consciousness, which are produced by cortex". They also propose that the "nucleus reticularis thalami" (Thalamic Reticular Nucleus, TRN), which is a thin sheet of neurons that covers the thalamus, is involved in a selective attention system. This concept is reinforced by the way that point stimulation of the TRN causes focal activity in the overlying cortex (MacDonald et al. 1998) and the way the TRN is organised topographically (i.e.: has activity that is like an electrical image of receptor fields).

The thalamus is ideally placed for integrating brain activity, if tiny parts of the thalamus are removed consciousness is abolished and the thalamus is involved in attention and the global integration of cortical activity. Any impartial judge might pronounce that the site of conscious experience has been found, possibly in the ILN of the thalamus, but no one can say how it works.

General Anaesthesia and the Thalamus
General anaesthesia should result in a profound depression of activity in the ILN if these are indeed the sites of the conscious state. White & Alkire (2003) administered halothane or isoflurane to volunteers and used positron emission tomography (PET) to monitor brain activity. They found severe depression of activity in the thalamus. The depression appeared to be higher in the non-specific nuclei than in the relay nuclei of the thalamus. In other words the anaesthesia is neither turning off the cortex nor turning off the input to the cortex but it is turning off an important part of the thalamus. Fiset et al. (1999) have also demonstrated a similar pattern of medial thalamic inactivity and cortical activity in propofol anaesthesia. Suppression of cortical activity is not the cause of unconsciousness; for instance, the anaesthetic agent chloralose leads to increased neural activity in the cortex relative to conscious patients (Cariani 2000).

The function of consciousness
When we walk our conscious experience does not contain data about the control of the spinal, cerebellar and vestibular reflexes that keep us on an even keel. When we reach out for a cup our conscious experience only contains data related to the need for the cup, not data about the elaborate control system that enables the action. When we talk the words just come into mind, we do not painstakingly control the syntax and vocal chords. When our attention shifts the conscious experience containing the shift happens after the attention has shifted. This passive nature of experience recurs throughout the neuroscience of consciousness from the "readiness potential" to the "auditory continuity illusion". So what does conscious observation do? The medical evidence of the lack of consciousness in some forms of delirium, mutism, PVS etc. suggest that the role of conscious observation is to stabilise the brain so that it acts as a coordinated whole. Conscious observation is an orderly arrangement of events, a stable groundform that reflects the environment and composes the stage for action. It could be speculated that if quantum events were prominent in brain function then such a groundform would be essential but even a classical brain might require a stabilising form that could be continuously compared with the world beyond the body.

A stable form of neural information that contains bound data from the senses and internal neural processes is likely to have a role in the functioning of the organism. There is now an integration consensus that proposes that phenomenal states somehow integrate neural activities and information-processing that would otherwise be independent (see review in Baars, 2002).

However, it has remained unspecified which kinds of information are integrated in a conscious manner and which kinds can be integrated without consciousness. Obviously not all kinds of information are capable of being disseminated consciously (e.g., neural activity related to vegetative functions, reflexes, unconscious motor programs, low-level perceptual analyses, etc.) and many kinds can be disseminated and combined with other kinds without consciousness, as in intersensory interactions such as the ventriloquism effect.

Morsella (2005) proposed a Supramodular Interaction Theory (SIT) that contrasts the task demands of consciously penetrable processes (e.g.: those that can be part of conscious experience such as pain, conflicting urges, and the delay of gratification) and consciously impenetrable processes (e.g.: intersensory conflicts, peristalsis, and the pupillary reflex). With this contrastive approach, SIT builds upon the integration consensus by specifying which kinds of interaction require conscious processing and which kinds do not (e.g., some intersensory processes). SIT proposes that conscious processes are required to integrate high-level systems in the brain that are vying for (specifically) skeletomotor control, as described by the principle of parallel responses into skeletal muscle (PRISM). Accordingly, regarding processes such as digestion and excretion, one is conscious of only those phases of the processes that require coordination with skeletomotor plans (e.g., chewing or micturating) and none of those that do not (e.g., peristalsis). From this standpoint, consciousness functions above the level of the traditional module to “cross-talk” among high-level, specialized and often multi-modal, systems.

References

Baars, B. J. (2002). The conscious access hypothesis: Origins and recent evidence. Trends in Cognitive Sciences, 6, 47 – 52.

Morsella, E. (2005). The function of phenomenal states: Supramodular interaction theory. Psychological Review, 112, 1000 - 1021.

More... Click here for Rivalries and synchronisation, bibliography and references

title: Consciousness Studies/Neuroscience 1


text:
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Consciousness Studies/Introduction

Everyone has their own view of the nature of consciousness based on their education and background. The intention of this book is to expand this view by providing an insight into the various ideas and beliefs on the subject as well as a review of current work in neuroscience. The neuroscientist should find the philosophical discussion interesting because this provides first-person insights into the nature of consciousness and also provides some subtle arguments about why consciousness is not a simple problem. The student of philosophy will find a useful introduction to the subject and information about neuroscience and physics that is difficult to acquire elsewhere.

It is often said that consciousness cannot be defined. This is not true; philosophers have indeed defined it in its own terms. It can be described in terms of two principal components: firstly phenomenal consciousness which consists of our experience with things laid out in space and time, sensations, emotions, thoughts, etc., and secondly access consciousness which is the processes that act on the things in experience. Phenomenal consciousness is much like the “perceptual space” of psychological and physiological research. It is the many simultaneous events that become the space of experience in general and it is now a legitimate target of scientific research.

As will be seen in the following pages, the issue for the scientist and philosopher is to determine the location and form of the things in phenomenal consciousness and even to consider whether such a thing could exist. Is phenomenal consciousness directly things in the world beyond the body, is it brain activity based on things in the world and internal processes — a sort of virtual reality — or is it some spiritual or other phenomenon?

A note on Naive Realism
The study of consciousness may seem to be esoteric or outside of the main stream but it includes some very real problems in science and philosophy. The most obvious problem is how we can see anything at all. Many people with a smattering of geometry tend to believe that they have a 'point eye' that sees the world, and this idea is known as perceptual "Naive Realism". Physical considerations show that this idea is highly contentious; we have two eyes with different images in each, normally the only images in the world are created by optical instruments such as the eye, and the photons that carry light to the observer cannot and do not all converge at a single point. Some of the discrepancies between the physical reality and our experience are shown in the illustrations.

The naive realist idea of perception involves a point eye looking at a geometrical form. But the physics is different; there are two eyes with sometimes very different images in each. Light is refracted over the entire area of the cornea and directed over the entire area of the retina - there is no 'point eye'.

The cloud of photons that compose light must get in the way of the view but naive realism neglects this, regarding the photons as somehow transparent yet gathering as an impossible group of millions of photons in a viewing point.

Light rays go everywhere, it is only after light has passed through an optical instrument such as the eye that an image is formed. Hold up a sheet of paper - there are no images on it.

The illustrations show the nature of one of the most difficult problems studied by neuroscience: how can the images on the two retinas become experience? How can we imagine things or experience dreams and hallucinations? Studies on the neural basis of binocular rivalry and MRI studies of imagination are leading the way in our comprehension of these problems but there is still no physical theory that is congruent with sensory experience. The problem of binding also takes us further from Naive Realism; we experience speech at the mouth of the speaker even though we might be listening through headphones, how is sound, touch etc. bound to vision? The objective of the scientific study of consciousness is to discover how we convert data from the world into our experience.

A degree of Naive Realism is a sensible idea for coping with the everyday problems of working and living. Most physical scientists and people in general are, to some extent, Naive Realists until they study the biology of sensation and the problems of perception and consciousness. There is often a suspicion, or even fear, amongst Naive Realists that any analysis of conscious experience is a suggestion that the world does not exist or everything is imaginary. These fears are unfounded: Neuroscience is a study of the part of the physical world represented by brain activity and is part of medicine.

Intended audience and how to read this book
This book is intended as a complementary text for neuroscience and philosophy degree courses. The book is divided into four parts. If you are not interested in some part, skip to the next. The first part is a detailed historical review of the philosophy of phenomenal consciousness. The second part is a discussion of philosophical theories, it is intended to be challenging and even irritating. Philosophy undergraduates are encouraged to criticise and react to this part. The third part is a review of the neuroscience of consciousness and is suitable for undergraduate studies in the field. The end of the book is a discussion of theories of consciousness.

Being freely available to all students the book can serve as a source for seminars even if you disagree with the content i.e.: “Why is (a given section) an oversimplification/biased/out of date etc.?”

The text covers a difficult area that straddles the humanities and science faculties. It is probably more oriented towards the scientist who needs a scientific insight into philosophical theory rather than vice versa. It is suitable as a supplementary text for the following undergraduate modules, units and courses:

 * Neurophysiology/Neurobiology modules (physiology of perception, physiology of consciousness, neuronal basis of consciousness)
 * Neuropsychology modules
 * Neuroanatomy modules
 * Cognitive psychology/Cognitive science
 * Psychology of consciousness
 * Psychology - behaviourism vs cognitivism debate
 * Philosophy of mind and metaphysics
 * Computing - Artificial intelligence and consciousness
 * Consciousness studies courses

This is a “Wikibook” and, in this edition, has more breadth than depth. In some areas, particularly in the huge field of the philosophy of consciousness, topics are introduced and the obvious flaws or successes pointed out but a fully referenced, in-depth treatment is sometimes absent at this stage. We need your help and contributions from scholars in the field are invited. Please contribute but, at the very least, scan the book first to ensure that your prospective contribution has not been included already! In particular contributors who wish to write “all self respecting scientists think that the brain is a digital computer” should read the section on information theory and add their contribution to the section on the possibility of conscious digital computers.

title: Consciousness Studies/Introduction


text:
User talk:Killedthecat

I just thought it would be a good idea to leave you a short message to encourage you to contribute to the school of philosophy this summer.

Thank you for your comments on the courses. (Alex beta 11:15, 21 Jun 2005 (UTC))

title: User talk:Killedthecat


text:
Talk:Information Ecology/Opening Page

It's hard to read the black text as it's a bit too close Charlie123 12:17, 21 Jun 2005 (UTC)

title: Talk:Information Ecology/Opening Page


text:
User talk:193.225.58.42

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title: User talk:193.225.58.42


text: Template:Screenplay/Begin

title: Template:Screenplay/Begin


text: Template:Screenplay/End

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Puzzles/How do you ... ?/Sending a Package

Dmitri, who lives in Moscow, has bought a pretty necklace for his fiancee Ana, who lives in St Petersburg. He wishes to send the necklace to her via post, but due to problems in the Russian postal service, he fears the package will be opened and the necklace stolen.

 * There is a considerable distance between the two cities.
 * Both Dmitri and Ana own a number of locks, chains, and keys.
 * Ana does not, however, own a key to any of Dmitri's locks, and vice versa.

How can he send the necklace to her?

Solution


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Puzzles/How do you ... ?/Sending a Package/Solution

 * Dmitri secures the package with a padlock and chain and sends it to Ana.
 * Ana attaches another padlock to the package and locks it. She then sends the package back to Dmitri.
 * Dmitri removes his padlock and sends the package back to Ana.
 * Ana removes her padlock and opens the package.

alternative:
 * Dmitri sends the locked package to Ana while also sending a separate letter with the key a few days later. Or if a combination lock, Dmitri sends a letter a few days later with the code.

problem with above:
 * the unlocked letter with the key may be opened and the key stolen..


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Puzzles/Lateral puzzles/7

Puzzles | Lateral puzzles | 7

A man was dead and completely naked in a padded cell. Apart from the body, there was absolutely nothing in the cell.

Explain...

Solution

title: Puzzles/Lateral puzzles/7


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Puzzles/Lateral puzzles/7/Solution

Puzzles | Lateral puzzles | Lateral puzzle 7 | Solution

Possible explanations:
 * The cell contained nothing, not even oxygen, so the man had asphyxiated.

 * The cell is a coffin, the man was dead before he was put into it and buried (and he was naked because he was a naturist).
 * The man was in a mental institution where he took a fatal allergic reaction to medication he was prescribed - or he did not swallow his medicines at the prescribed time but saved it in order to overdose.
 * The man was in a mental institution and the temperature drops. Since he was naked he died of hypothermia (this actually happened in a real hospital once)

title: Puzzles/Lateral puzzles/7/Solution