EA Joan Duprez
email: duprez.joan@gmail.com

Jean-François Houvenaghel

Soizic Argaud

Florian Naudet

Gabriel Robert

Dominique Drapier

Marc Vérin

Paul Sauleau

Impulsive oculomotor action selection in Parkinson's disease

Keywords: Cognitive action control, Parkinson's disease, Impulsivity, Activation-suppression, Simon task

The effects of Parkinson's disease (PD) on the dynamics of impulsive action selection and suppression have recently been studied using distributional analyses, but with mixed results, especially for selection. Furthermore, some authors have suggested that impulsivity, regarded as a personality trait, shares common features with behavioral tasks' measures. The current study was designed to clarify the impact of PD on impulsive action selection and suppression, and investigate the link between cognitive action control and self-reported impulsivity. We administered an oculomotor version of the Simon task to 32 patients with PD and 32 matched healthy controls (HC), and conducted distributional analyses in accordance with the activation-suppression model. Patients and HC also filled out the Barratt Impulsiveness Scale (BIS) questionnaire. Results showed that patients with PD were faster overall and exhibited a greater congruence effect than HC. They also displayed enhanced impulsive action selection. By contrast, the suppression of impulsive responses was similar across both groups. Furthermore, patients had higher impulsivity scores, which were correlated with higher impulsive action selection and higher suppression. Our study yielded two interesting findings. First, PD resulted in a higher number of fast errors. The activation-suppression model suggests that patients with PD are more susceptible to the impulsive action selection induced by the irrelevant stimulus dimension. Second, impulsive action selection and suppression were both associated with trait impulsivity, as measured by the BIS, indicating that these two aspects of impulsivity share common features.

Introduction

Efficient cognitive control is vital when a choice has to be made between strong response alternatives. One of the underlying functions of cognitive control, the online resolution of conflict situations, also known as cognitive action control, has been extensively studied. Experimental tasks that put the participants in a situation of conflict between two response alternatives typically show that conflict resolution has a cognitive cost. One of the most widely used conflict-inducing paradigms is the Simon task [START_REF] Simon | Effect of conflicting cues on information processing: the "Stroop effect" vs. the "Simon effect[END_REF].

In this task, participants have to press a button according to the color of a circle displayed on either the right-or lefthand side of a screen. In incongruent situations, the color of the stimulus and its display side activate opposite responses, while in congruent situations, both items of information trigger the same response. Simon task studies have repeatedly shown that incongruent situations lead to an increase in reaction times (RTs), reflecting the so-called Simon effect or congruence effect, and a decrease in accuracy [START_REF] Hedge | The effect of irrelevant spatial correspondences on twochoice response-time[END_REF][START_REF] Simon | Reactions toward the source of stimulation[END_REF][START_REF] Simon | Effect of conflicting cues on information processing: the "Stroop effect" vs. the "Simon effect[END_REF][START_REF] Van Der Lubbe | Aging and the Simon task[END_REF][START_REF] Wöstmann | Reliability and plasticity of response inhibition and interference control[END_REF].

The congruence effect is usually explained by dual-route models, which posit that response activation can follow two parallel routes: an automatic one and a controlled one [START_REF] Kornblum | Dimensional overlap: cognitive basis for stimulus-response compatibility-a model and taxonomy[END_REF]. According to this view, the automatic route favors the expression of overlearned actions, while the controlled route fosters intention-driven behavior. Thus, during conflict tasks, the irrelevant dimension of the stimulus triggers a fast response through the automatic route, while the relevant dimension triggers a slower, goal-directed response through the controlled route. Accordingly, in the congruent situation, the automatic and controlled routes both support the same response, leading to response facilitation. In the incongruent situation, however, the two routes activate contrasting motor programs, and the individual must be able to suppress the automatic response activated by the irrelevant information in favor of the goal-directed one.

A recent model of cognitive action control refined the dual-route hypothesis by distinguishing between the processes of response selection and suppression. The activation-suppression model suggests that a selective inhibition mechanism is set up to suppress the inappropriate activation elicited by the irrelevant stimulus dimension [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF]. However, this selective inhibition takes time to build up. As a consequence, the inappropriate automatic activation is hard to suppress immediately after stimulus presentation. The fastest responses in the incongruent situation are therefore more error prone. This has been highlighted using conditional accuracy functions (CAFs), which display accuracy as a function of the RT distribution divided into bins. The fastest responses (those in the first bin) are thought to reflect automatic activation by the irrelevant dimension, with a higher number of fast errors in the incongruent situation indicating more impulsive action selection. As the selective inhibition of this impulsive action selection takes time to become effective, we can assume that the inappropriate activation is more efficiently suppressed when responses are slow. This assumption is supported by delta plots describing the congruence effect (incongruent RTs minus congruent RTs for correct responses) as a function of RT distribution. Simon task delta plots typically show a decrease in the congruence effect as RTs increase, and the slope between the last two bins is thought to reflect the strength of the selective inhibition process, with a steeper negative slope corresponding to stronger inhibition (see van den Wildenberg et al., 2010, for a review). The fast error rate in CAFs and the strength of the last slope in the delta plots are increasingly being used as parameters to assess impulsive action selection and suppression in both healthy and pathological populations [START_REF] Castel | Spatial attention and response control in healthy younger and older adults and individuals with Alzheimer's disease: evidence for disproportionate selection impairments in the Simon task[END_REF][START_REF] Juncos-Rabadán | Cognitive interference and aging: insights from a spatial stimulus-response consistency task[END_REF][START_REF] Proctor | The enhanced Simon effect for older adults is reduced when the irrelevant location information is conveyed by an accessory stimulus[END_REF][START_REF] Van Der Lubbe | Aging and the Simon task[END_REF]Wylie et al., 2009a).

Cognitive action control is mostly supported by a prefrontal-basal ganglia network (see Ridderinkhof et al., 2011, for a review). More specifically, the pre-supplementary motor area (pre-SMA), which is part of the supplementary motor complex, the inferior frontal cortex (IFC), and the subthalamic nucleus (STN) are all thought to play a major role in impulsive action selection and suppression. The STN is thought to share direct connections with the pre-SMA and the IFC, forming a network that supports conflict resolution [START_REF] Aron | Converging evidence for a fronto-basal-ganglia network for inhibitory control of action and cognition[END_REF][START_REF] Majid | Proactive selective response suppression is implemented via the basal ganglia[END_REF][START_REF] Mink | The basal ganglia: focused selection and inhibition of competing motor programs[END_REF]. For instance, a study focusing on the effect of deep brain stimulation of the STN in patients with Parkinson's disease (PD) revealed that electrical stimulation of the STN results in more impulsive action selection and enhanced late selective inhibition (Wylie et al., 2010b). The role of the STN in inhibitory control has also been confirmed by direct recordings in patients with PD, which have revealed changes in activity relative to stopping performance in a stop signal task [START_REF] Alegre | The subthalamic nucleus is involved in successful inhibition in the stop-signal task: a local field potential study in Parkinson's disease[END_REF], and by the study of PD patients who underwent subthalamotomy [START_REF] Obeso | The subthalamic nucleus and inhibitory control: impact of subthalamotomy in Parkinson's disease[END_REF].

Since cognitive action control relies on prefrontal-basal ganglia networks, we would expect diseases that affect these brain networks, such as PD, to hinder its efficiency. Most of the studies that have investigated cognitive action control so far have found that conflict resolution is indeed impaired in patients with PD, as indicated by a higher congruence effect [START_REF] Brown | Response choice in Parkinson's disease. The effects of uncertainty and stimulus-response compatibility[END_REF][START_REF] Pinheiro | Motor cortex activation in Parkinson's disease: dissociation of electrocortical and peripheral measures of response generation[END_REF][START_REF] Praamstra | Reliance on external cues for movement initiation in Parkinson's disease. Evidence from movement-related potentials[END_REF][START_REF] Praamstra | Failed suppression of direct visuomotor activation in Parkinson's disease[END_REF][START_REF] Schmiedt-Fehr | Parkinson's disease and age-related alterations in brain oscillations during a Simon task[END_REF][START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF][START_REF] Wylie | Activation of conflicting responses in Parkinson's disease: evidence for degrading and facilitating effects on response time[END_REF], although some studies have failed to observe this effect [START_REF] Cagigas | Flanker compatibility effects in patients with Parkinson's disease: impact of target onset delay and trial-by-trial stimulus variation[END_REF][START_REF] Falkenstein | Effects of stimulusresponse compatibility in Parkinson's disease: a psychophysiological analysis[END_REF][START_REF] Lee | Selective visual attention in patients with frontal lobe lesions or Parkinson's disease[END_REF]. This impairment has been shown to depend on dopaminergic treatment [START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF] and disease characteristics such as motor symptom severity [START_REF] Vandenbossche | Conflict and freezing of gait in Parkinson's disease: support for a response control deficit[END_REF][START_REF] Vandenbossche | Freezing of gait in Parkinson disease is associated with impaired conflict resolution[END_REF]Wylie et al., 2010a). However, very few studies have investigated the effect of PD on the dynamics of cognitive action control as proposed by the activation-suppression model.

Most of these studies assessed PD patients with dopaminergic medication and their results are somewhat inconsistent. Although most of them describe impaired selective inhibition in patients, revealed by a less negative final delta-plot slope [START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF]Wylie et al., 2010aWylie et al., , 2009aWylie et al., , 2009b)), the effect of PD on impulsive response selection is unclear. For example, when Wylie et al. (2009a) used a flanker task to assess medicated patients with PD, they found that patients exhibited a greater congruence effect than HC, and stronger impulsive response selection, as revealed by a lower accuracy rate for the first CAF bin. In a subsequent study, however, they failed to demonstrate an increased congruence effect or increased susceptibility to response capture, except in patients with the most severe motor symptoms (Wylie et al., 2010a). The reasons for such mixed results are uncertain. It is possible that heterogeneity in the experimental methods might play a role. For example, Wylie et This could be explained by the nature of the stimuli, known to influence the strength of the conflict [START_REF] Wascher | Spatial SR compatibility with centrally presented stimuli: An event-related asymmetry study on dimensional overlap[END_REF][START_REF] Mattler | Priming of mental operations by masked stimuli[END_REF]. It is also possible that heterogeneity in the patients' characteristics might have influenced the performance. For instance, Wylie et al. (2010) showed that the severity of the motor symptoms had an impact on the amount of fast errors. Among the studies investigating the effect of PD on the dynamics of cognitive action control, only one assessed PD patients without dopaminergic medication [START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF]. This study revealed no difference between patients without medication and healthy controls in impulsive action selection. While this suggests that there is no pure PD effect on impulsive action selection, it remains unclear whether PD patients with their usual medication are impaired or not in this process. It therefore remains unclear whether patients with PD display greater impulsive action selection.

Patients with PD have been shown to be faster than HC in the oculomotor response modality, and oculomotor versions of the Simon task have been found to yield more errors than manual versions [START_REF] Fielding | No sequence dependent modulation of the Simon effect in Parkinson's disease[END_REF][START_REF] Sullivan | An oculomotor Simon effect[END_REF]. We suggest that most errors in the oculomotor tasks are fast errors, as predicted by the activation-suppression model, and that oculomotor versions of the Simon task are more useful for gauging impulsive action selection. We therefore hypothesized that if patients with PD are characterized by greater impulsive action selection, an oculomotor version of the Simon task is more likely to bring it to light. We also chose to use the oculomotor modality as there is a great amount of studies on the impact of PD on saccades performances that may, in part, rely on impairment in cognitive action control. For example, PD usually impairs volitional saccades (slowing RT and decreasing accuracy, see [START_REF] Terao | New perspectives on the pathophysiology of Parkinson's disease as assessed by saccade performance: A clinical review[END_REF] for a review) while visually-guided saccades are relatively spared. Furthermore, investigating conflict effect on eye movements has an important implication regarding the ability to ignore irrelevant stimuli from the environment and favor relevant ones. This is of major interest in PD as these patients have been shown to be more attracted than controls by irrelevant visual stimuli [START_REF] Deijen | Abnormal susceptibility to distracters hinders perception in early stage Parkinson's disease: a controlled study[END_REF][START_REF] Van Stockum | A perceptual discrimination task abnormally facilitates reflexive saccades in Parkinson's disease[END_REF] .The first objective of the current study was thus to confirm this effect of PD on cognitive action control using an oculomotor version of the Simon task that has yielded results consistent with the activation-suppression model in healthy controls [START_REF] Duprez | Evaluating cognitive action control using eyemovement analysis: an oculomotor adaptation of the Simon task[END_REF]. We hypothesized that if PD results in greater impulsive action selection, it would increase the number of fast errors in CAF.

Our second objective was to investigate the relationship between cognitive action control abilities and impulsivity, treated as a personality trait. More specifically, we wondered whether there is a link between impulsive action selection and suppression in conflict tasks such as the Simon task and self-reported impulsivity. Some studies have reported inconsistent results regarding the potential link between different measures of impulsivity [START_REF] Aichert | Associations between trait impulsivity and prepotent response inhibition[END_REF][START_REF] Caswell | Further evidence of the heterogeneous nature of impulsivity[END_REF]. The activation-suppression model allows for the investigation of impulsive action selection and suppression, and we argued that this link appears when focusing on the first CAF bin or last delta-plot slope. We therefore sought to evaluate the link between self-reported impulsivity, as assessed by the BIS-10 questionnaire [START_REF] Baylé | Structure factorielle de la traduction française de l'échelle d'impulsivité de Barratt[END_REF], and the dynamics of cognitive action control in patients with PD and HC. More specifically, we sought to investigate the relationship between the total score and cognitive and motor subscores on the questionnaire and the processes of impulsive action selection and suppression. To this end, we conducted correlation analyses between BIS-10 scores and measures of the fastest responses in conflict situations, as reflected by the first CAF bin, and the steepness of the last slope of the delta plot. We predicted that distributional analyses would reveal a link between the number of fast errors, the steepness of the last delta-plot slope, and the BIS-10 scores. This link would indicate that higher impulsivity scores are associated with more impulsive action selection and impaired selective inhibition in both HC and patients with PD.

Methods

Participants

Thirty-two HC and 32 patients with idiopathic PD (Hughes et al., 1992) took part in this study (Table 1). They did not significantly differ on age, sex or education. The patients with PD were recruited from the Neurology Department of Rennes University Hospital (France). All patients had mild to moderate disease severity (Stages I-III in the on-medication state; [START_REF] Hoehn | Parkinsonism onset, progression, and mortality[END_REF] and were free from all other neurological or psychiatric pathologies, including impulsive-compulsive disorders. They all had a Mattis Dementia Rating Scale (MDRS) score > 130 that excluded dementia (Mattis, 1988). The severity of their motor symptoms was assessed using the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS-III). All patients were on dopaminergic replacement medication and were assessed in their on-medication state for all parts of the experiment. Five patients were on levodopa only, one was on dopamine agonists only, and 26 were on both levodopa and dopamine agonists. All the healthy participants underwent an extensive interview to ensure that they had no history of neurological or psychiatric pathology, and no recent drug use. All participants, including patients, had normal or corrected-to-normal vision and gave their written informed consent. They all completed the BIS-10 questionnaire [START_REF] Baylé | Structure factorielle de la traduction française de l'échelle d'impulsivité de Barratt[END_REF].

This study was conducted with the approval of the local ethics committee of Rennes University Hospital and in accordance with the Declaration of Helsinki and current French legislation (Huriet Act).

Task design and procedure

The Simon task was designed using MeyeParadigm® software (Version 1.18, e(ye)BRAIN). Participants sat 60 cm away from a 22-inch screen and performed the whole task in darkness. The screen was positioned so that the stimuli appeared at eye level. The stimulus was a blue or yellow square (0.6 x 0.6 cm) displayed at a 12° visual angle on either the left-or righthand side of the screen (Fig. 1). Responses were saccadic eye movements made to the left or right. Each trial began with the display of a central white square (0.6 x 0.6 cm) that served as a fixation point for 875-1250 ms (125-ms pseudorandom steps). It was flanked by two contiguous rectangular cues (5 x 1 cm), one blue one yellow (Fig. 1). The target stimulus was then displayed on the left or right side of the screen for 1000 ms. The trial ended with a black screen displayed for 1250 ms before the next one started.

The color side of these cues was randomly reversed across participants. The targets were displayed randomly, with an equal number of 2 (color) x 2 (location) combinations. The task began with a 16-trial practice block and was followed by an experimental phase containing 300 trials divided into five blocks, each containing 60 trials. The blocks were separated by short breaks to avoid tiredness.

Eye movement recording and data analysis

Eye-movements were recorded with a head-mounted eyetracker (EyeBrain T2®, e(ye)BRAIN®). Horizontal saccades were recorded at a 300 Hz sampling rate and an angular resolution of 0.5°. Saccade RTs and accuracy were analyzed off line with MeyeAnalysis® software (e(ye)BRAIN®). Saccade detection was based on an algorithm adapted from [START_REF] Nyström | An adaptive algorithm for fixation, saccade, and glissade detection in eyetracking data[END_REF]. The first saccade after stimulus presentation was taken to be the participant's response and was counted as correct when it corresponded to the side indicated by the color of the target stimulus. We excluded all saccades with an amplitude below 2° (to discard micromovements around the fixation point), a latency below 100 ms (corresponding to anticipated responses; see [START_REF] Leigh | The neurology of eye movements[END_REF] or above 1000 ms (corresponding to target duration), and outlier latencies more than three standard deviations from the mean RT. We removed 1.4% of the whole dataset from the analyses with these parameters. Mean RTs for correct trials and accuracy scores were calculated for each group and each congruence condition, to assess the effect of group on the congruence effect. We further analyzed the data with distributional analyses, in accordance with the activation-suppression model [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF]. First, we used CAFs displaying accuracy as a function of RT to assess automatic response activation. To do this, we plotted accuracy levels against the RT distribution for each congruence condition and by group. For each participant, RTs were rank-ordered and split into seven bins containing an equal number of trials, and mean accuracy was then plotted for each bin. Second, we created delta plots to assess the dynamics of selective suppression. We plotted the mean congruence effect (incongruent RT minus congruent RT for correct trials) against RT distribution, which we then split into seven bins, as we did for the CAFs.

Statistical analysis

Data management and statistical analyses were performed using R © software (Version 3.1.0) implemented with the nlme (José Pinheiro (S version) et al., 2014) and lme packages (Bates et al., 2014). RTs were compared between congruence conditions and groups using a linear mixed model considering congruence and group as fixed effects and a random participant effect. As accuracy is a binary parameter, we used a nonlinear mixed model with the same fixed and random effects. We chose to use these models because they allowed us to work on the whole dataset, thus avoiding the loss of power that comes with averaging data. They also allowed us to take interindividual variability and unbalanced data into account (see [START_REF] Gueorguieva | Move over anova: Progress in analyzing repeatedmeasures data and its reflection in papers published in the archives of general psychiatry[END_REF]. The CAF analysis was performed using the same nonlinear mixed model, to which a bin factor was added. This resulted in a 2 (congruence) * 2 (group) * 7 (bin) design. A distinct analysis was performed on the first bin of CAF since accuracy for the fastest responses is considered above all as the key variable to assess impulsive action selection while other bins have little importance on this aspect according to the activationsuppression model (van den Wildenberg et al., 2010). Concerning the delta plots, we compared the dynamics of selective inhibition between groups. To this end, we computed slope values, which are usually used as measure of the strength of selective inhibition. We compared the slope values using a linear mixed model with slope (position in RT distribution)

and group as fixed effects, and participant as a random effect. This resulted in a 2 (group) * 6

(slope) design. Since the activation-suppression model postulates that the last slope of the delta plots allows the assessment of the strength of the selective inhibition mechanism, we conducted a distinct analysis on this last slope [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF]. All p values for linear mixed models were computed using the anova function that uses F tests, while p values for nonlinear mixed models were computed with the Anova function that calculates Wald chisquare tests (Anova {car}). Post hoc Tukey tests were used for further analyses when significant effects were found. The adjusted p values were obtained with the Tukey glht function from the multcomp package, which uses individual z tests instead of t-test when mixed models are used [START_REF] Hothorn | The multcomp package[END_REF]. Finally, we conducted correlation analyses between the measures of impulsive response selection (accuracy for the first bin of the incongruent CAF), suppression (steepness of the last delta-plot slope) and the BIS-10 scores with Spearman's rank correlation tests. For all our analyses, we used a significance threshold of p = 0.05.

Results

Group effects on overall congruence effect

Patients with PD responded faster than HC, irrespective of the congruence of the situation, as revealed by a significant group effect on RTs, F(1, 31) = 5.07, p = 0.03. The classic congruence effect was observed, with longer RTs in the incongruent versus congruent situation, F(1, 14382) = 624.9, p < 0.0001. Thus, all participants were slower overall when the relevant and irrelevant dimensions of the stimulus dictated conflicting responses. However, although both groups were affected by conflict situations, the congruence effect was greater in the patients with PD (74.4 ms) than in HC (34.6 ms; Fig. 2A). This was confirmed by a significant interaction between group and congruence, F(1, 14382) = 79.1, p < 0.0001. This difference arose because the patients were faster than HC in the congruent situation (z = -3.06, p = 0.008), whereas they had similar RTs in the incongruent situation (z = -1.1, p = 0.6).

Concerning accuracy, patients made more errors overall than HC (χ² = 12.4, p = 0.0004). We also observed a congruence effect on accuracy, with more errors in the incongruent versus congruent situation (χ² = 1303.8, p < 0.0001). The size of the congruence effect on accuracy also differed between groups (χ² = 53.8, p < 0.0001). Patients made more errors than HC in the incongruent situation (39.1 vs 21.3; z = -4.3, p < 0.0001), whereas both groups displayed similar accuracy in congruent situations (9.2 vs 7.3; z = -1.3, p = 0.5).

Group effects on impulsive response selection

To assess group differences in impulsive response activation dynamics, we analyzed the data with CAFs, which showed accuracy as a function of the RT distribution divided into seven bins. Figure 3 shows the CAFs of HC and patients for the incongruent (Fig. 3A) and congruent (Fig. 3B) situations. Congruence had a strong overall impact on accuracy (χ² = 1103.9, p < 0.0001). However, the extent of this congruence effect differed between groups, with a greater effect in patients than in HC (χ² = 11.9, p = 0.0005). Importantly, the congruence effect depended strongly on the time taken to respond. Faster RTs were associated with more fast errors in the incongruent situation, as revealed by a significant interaction between congruence and bin (χ² = 537.6, p < 0.0001). The overall dynamics of the congruence effect did not change between groups, as the interaction between congruence, bin and group failed to reach significance (χ² = 9.5, p = 0.14). However, the variance associated with the other bins is likely to mask this effect (Wylie et al., 2009b). Furthermore, impulsive action selection is best portrayed by the first bin of CAF according to the activation-suppression model. Accordingly we conducted a distinct analysis focusing on the first bin. The congruence effect was far stronger in patients that in HC, owing to a higher proportion of fast errors in the PD group (78.6% in PD vs. 54.1 % in HC; χ² = 31.4, p < 0.0001). This was confirmed by post hoc tests revealing that patients and HC were equally accurate in the congruent situation (z = 0.6, p = 0.9), but differed strongly in the incongruent situation (z = -5.1, p < 0.0001). Furthermore, Figure 3 suggests that the patients' first bin represented shorter

RTs than the HC bin did. This was confirmed by the significant difference in RTs for the first bin between the PD and HC groups, F(1, 31) = 15.5, p < 0.0001. These results mean that the patients with PD responded faster and displayed greater impulsive action selection elicited by the irrelevant stimulus dimension than HC.

Group effects on selective inhibition

We used delta plots to assess the strength of selective inhibition. According to the activation-suppression model, the slopes between the bins of the congruence effect best reflect the strength of this process. Figure 4 shows the typical decreasing delta plots for both patients and HC. Our analyses first revealed that the slopes were more negative for the slowest segments of the RT distribution, F(1, 318) = 6.7, p = 0.01. Faster RTs were associated with slopes that were less steep, indicating that selective inhibition was not as effective as it was for slower responses. The overall slope of the congruence effect was the same for both groups, indicating that selective inhibition was similar for both HC and patients, F(1, 31) = 0.46, p = 0.5. We focused our final analysis on the last segment of the delta plots, which is the most informative when it comes to the strength of selective inhibition. This analysis confirmed that selective inhibition was similar for both patients and HC, with no difference in the steepness of the last slope, F(1, 31) = 0.5, p = 0.48.

Relationship between trait impulsivity and impulsive action selection and suppression

We did not find any correlation among HC between the BIS-10 scores and either the accuracy of the first CAF bin for the incongruent situation, or the steepness of the last deltaplot slope (all ps > 0.05). Among the patients, however, we found a negative correlation between accuracy for the first CAF bin in the incongruent situation and both the BIS-10 total score (r = -0.38, p = 0.03) and its cognitive (r = -0.37, p = 0.03) and motor (r = -0.38, p = 0.03) subscores. In other words, greater impulsivity, as assessed by the questionnaire, was associated with greater impulsive action selection in the task. Furthermore, the last delta-plot slope was negatively correlated with the BIS-10 total score (r = -0.36, p = 0.04) and cognitive subscore (r = -0.36, p = 0.04), meaning that higher scores on the questionnaire were accompanied by steeper last slopes of the delta plot. To ensure the absence of influential outliers, we checked Cook's distance and found no values above 0.5 (values below 1 being considered of little influence on the correlation; [START_REF] Cook | The relationship between self-report and lab task conceptualizations of impulsivity[END_REF]. We also found a positive correlation between accuracy in the first bin of CAF and the last delta-plot slope value in patients (r = 0.37, p = 0.03), meaning that higher accuracy in the first bin of CAF was associated with higher slope values, and thus, with weaker selective inhibition. As a whole, higher scores on the BIS-10 were associated with stronger impulsive action selection, but also with stronger late selective inhibition (Fig. 5). It should be noted that the patients with PD did not differ from HC on the BIS-10 scores (t = -0.38, p = 0.7).

Relationship with PD clinical features

We also investigated whether clinical features of PD were related to the measures of cognitive action control and its dynamics. To this end, we tested whether the overall congruence effect, the accuracy in the first bin of CAF and the last slope of the delta-plots were related to disease duration, disease severity (UPDRS motor score and Hoehn & Yahr ratings) and levodopa equivalent daily dose. We found no significant relationship between those task results and disease characteristics (all p > 0.10)."

Discussion

The purpose of this study was to investigate the impact of PD on cognitive action control and to specify the potential link between behavioral measures of impulsive action selection and suppression and trait impulsivity in both HC and patients. To this end, we used an oculomotor version of the Simon task [START_REF] Duprez | Evaluating cognitive action control using eyemovement analysis: an oculomotor adaptation of the Simon task[END_REF] and analyzed the results according to the activation-suppression model [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF]. The use of distributional analyses as per this model allowed us to investigate impulsive action selection and suppression, both of which are regarded as core mechanisms of cognitive action control. We also used correlation analyses to investigate the specific link between the measures of these two mechanisms and self-reported impulsivity, as assessed by the BIS-10. Our main prediction was that patients with PD would display more impulsive action selection than HC, and less proficient engagement of the selective inhibition mechanism. We further expected measures of impulsive action selection and suppression to be associated with BIS-10 impulsivity scores in both HC and PD.

We found the typical congruence effect on RT and accuracy, showing that conflict situations generate longer RTs and more errors. This effect was greater in patients with PD than HC, meaning that patients experienced greater difficulty resolving conflict situations.

Greater congruence effects in patients have already been reported in several studies, whether

or not the patients were on medication [START_REF] Pinheiro | Motor cortex activation in Parkinson's disease: dissociation of electrocortical and peripheral measures of response generation[END_REF][START_REF] Praamstra | Reliance on external cues for movement initiation in Parkinson's disease. Evidence from movement-related potentials[END_REF][START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF][START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF]Wylie et al., 2009a[START_REF] Wylie | Activation of conflicting responses in Parkinson's disease: evidence for degrading and facilitating effects on response time[END_REF]. Importantly, the greater congruence effect observed in our study was due not to slowing in the incongruent situation, but rather to the fact that patients were faster than HC in the congruent situation, as already reported by [START_REF] Pinheiro | Motor cortex activation in Parkinson's disease: dissociation of electrocortical and peripheral measures of response generation[END_REF].

The reason why we did not observe faster responses by patients than by HC in the incongruent situation is because the congruence effect is based on correct responses. Most of the incorrect responses provided by patients in the incongruent situation had very fast RTs, as we discuss below. Thus, most of the responses in which patients were faster than HC in the incongruent situation did not appear in the analysis of the congruence effect because most of them were erroneous.

A number of studies investigating the impact of PD on impulsive action selection have used distributional analyses, in accordance with the activation-suppression model [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF]. Most of these studies assessed impulsive action selection and suppression in medicated PD patients. While some of them have demonstrated higher automatic activation in PD (Wylie et al., 2009a), which may be restricted to patients with the most severe motor symptoms [START_REF] Vandenbossche | Conflict and freezing of gait in Parkinson's disease: support for a response control deficit[END_REF]Wylie et al., 2010a) Moreover, patients were faster than HC in both the congruent and incongruent situations.

Thus, the increase in response speed in PD is probably the main explanation for the patients' dramatic decrease in accuracy in the incongruent situation. According to the activation-suppression model, the selective inhibition of erroneous responses is only effective when responses are delayed. Thus, responding faster increases the risk of errors. In addition, we observed that slower responses in PD were associated with accuracy similar to that of HC, supporting the notion that responding faster generates more errors.

As a whole, we found that patients' conflict resolution was impaired, and this impairment originated from greater impulsive action selection. The strength of selective inhibition seemed unaffected. We measured faster responses and a greater number of fast errors in PD patients compared to HC. Faster oculomotor reactions in PD patients have also been observed in another study using an oculomotor Simon task [START_REF] Fielding | No sequence dependent modulation of the Simon effect in Parkinson's disease[END_REF]. Faster responses would be expected by a speed-accuracy tradeoff biased toward speed. However, in an oculomotor Simon task, Fielding et al. (2005) strongly biased instructions toward accuracy and observed that PD patients were faster than healthy controls. They explained this enhanced speed in PD by the dysfunction of an inhibitory mechanism usually suppressing direct stimulus-driven response. Furthermore, while volitional saccadic eye-movements are altered in both RT and accuracy in PD, visually-guided saccades seem unaffected or even faster [START_REF] Briand | Control of voluntary and reflexive saccades in Parkinson's disease[END_REF][START_REF] Terao | New perspectives on the pathophysiology of Parkinson's disease as assessed by saccade performance: A clinical review[END_REF]. For example, [START_REF] Briand | Automatic orienting of visuospatial attention in Parkinson's disease[END_REF] also found that patients were faster than HC in a reflexive visual-orienting task. The authors explained this finding by surmising that patients with PD have hyper-reflexive orienting of spatial attention. Their explanation was based on the assumption that eye movements are controlled by two separate attentional systems: a voluntary one that is responsible for volitional eye movements and which inhibits more reflexive one that controls visually guided saccades. According to the authors, PD primarily disrupts the voluntary system, which involves the basal ganglia, freeing the reflexive system from inhibition and thus facilitating reflexive eye movements. These interpretations are in line with the explanation by [START_REF] Terao | New perspectives on the pathophysiology of Parkinson's disease as assessed by saccade performance: A clinical review[END_REF] who proposed that such faster responses could result from disinhibition of the superior colliculus secondarily to impairment of the prefrontal-basal ganglia networks in PD, and/or from overactivity in the parietal cortex that would compensate for the motor disorders. This view fits in well with the general assumption of dual-route models whereby stimulus processing in a conflict situation follows two parallel routes (a mainly automatic one and a controlled one) that converge to activate a response [START_REF] Kornblum | Dimensional overlap: cognitive basis for stimulus-response compatibility-a model and taxonomy[END_REF]. Thus, the greater congruence effect in our patients with PD may have resulted from hyper-reflexive orientation of attention.

Cognitive action control is thought to rely on prefrontal-basal ganglia circuits involve the pre-SMA, IFC, and STN [START_REF] Aron | Converging evidence for a fronto-basal-ganglia network for inhibitory control of action and cognition[END_REF]Forstmann et al., 2008aForstmann et al., , 2008b;;[START_REF] Spieser | Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors[END_REF]. Forstmann et al. (2008) used a Simon task coupled with fMRI to investigate the structures associated with the dynamics of response activation and suppression. They showed that higher impulsive action selection (portrayed by the first CAF bin) is associated with greater activity in the pre-SMA, while stronger selective inhibition (portrayed by the last delta-plot slope) is associated with greater activity in the IFC. Recent evidence from a study using transcranial direct current stimulation further confirms the role of the pre-SMA in the expression of impulsive actions [START_REF] Spieser | Controlling your impulses: electrical stimulation of the human supplementary motor complex prevents impulsive errors[END_REF], while the IFC has repeatedly been reported to be an important structure for inhibitory control [START_REF] Aron | Inhibition and the right inferior frontal cortex[END_REF]. Thus, higher impulsive action selection, as assessed by the number of fast errors in CAFs, is usually associated with activation of the pre-SMA in manual versions of the task (Forstmann et al., 2008a). Switching to an oculomotor response modality engages additional areas, such as the frontal and parietal eye fields, which are thought to be involved in volitional and reflexive eye movements, respectively [START_REF] Gaymard | Cortical and sub-cortical control of saccades and clinical application[END_REF]. Since these cortical areas are linked to the basal ganglia, and since PD disrupts prefrontal-basal ganglia circuits [START_REF] Watanabe | Probing basal ganglia functions by saccade eye movements[END_REF], an imbalance between the automatic and controlled systems might well occur, leading to a bias toward automatic activation. This would explain why patients made more fast errors in our study. An alternative explanation is that patients with PD have a different speed-accuracy trade-off strategy from controls. They may thus have focused their performance on speed rather than on balancing speed and accuracy, as instructed. However, focusing on speed would also induce greater selective inhibition difficulty, reflected in a less negative last deltaplot slope (Wylie et al., 2009a).

Still according to the activation-suppression model [START_REF] Ridderinkhof | Activation and suppression in conflict tasks: empirical clarification through distributional analyses[END_REF], a steeper negative last delta-plot slope is usually interpreted as reflecting stronger selective inhibition (see [START_REF] Van Den Wildenberg | To head or to heed? Beyond the surface of selective action inhibition: a review[END_REF], for a review). We also observed the classic Simon task's delta-plot pattern, with a decreasing congruence effect across RT distribution. This pattern was similar for both patients and HC, and a specific analysis of the last slope failed to reveal any group differences. This suggests that patients displayed asimilar inhibition of impulsive action selection to HC. This contrasts with previous studies, except for one recent one [START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF]. Most studies have shown a deficit in selective inhibition in PD, revealed by a less negative last delta-plot slope [START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF]Wylie et al., 2009a;Wylie et al., 2010a). This finding of selective inhibition difficulty is consistent with studies that have found impaired inhibition in patients with PD by assessing their performances on a stop task [START_REF] Gauggel | Inhibition of ongoing responses in patients with Parkinson's disease[END_REF][START_REF] Obeso | Deficits in inhibitory control and conflict resolution on cognitive and motor tasks in Parkinson's disease[END_REF].

One possible explanation for the discrepancy between the literature and our results is that the patients in our study were younger and their disease was less severe than in other studies (Wylie et al., 2010a(Wylie et al., , 2009a(Wylie et al., , 2009b)). As disease severity and age (assessed in HC) have been reported to modulate cognitive action control and the dynamics of activation and suppression [START_REF] Castel | Spatial attention and response control in healthy younger and older adults and individuals with Alzheimer's disease: evidence for disproportionate selection impairments in the Simon task[END_REF]Duprez et al., submitted;[START_REF] Juncos-Rabadán | Cognitive interference and aging: insights from a spatial stimulus-response consistency task[END_REF]Wylie et al., 2010a), these factors could account for some of the differences between our results and the literature. Another possible explanation is that the lack of difference in the delta plots could stem from the fact that we used an oculomotor response mode. The last delta-plot slope in most of the studies investigating PD with the Simon task covered RTs lasting 600-700 ms, whereas in ours, it covered RTs of 500-600 ms [START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF][START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF]Wylie et al., 2010aWylie et al., , 2009aWylie et al., , 2009b)). Our version of the task may therefore have generated responses that were too fast for the selective inhibition mechanism to be as fully engaged as it is in manual Simon tasks.

Our results did not reveal any relationship between task measures and dopaminergic medication dosage. Similarly, in a recent study comparing PD patients with and without dopaminergic medication, van [START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF] did not observe any correlation between treatment dosage and task results. These authors reported a positive effect of the treatment on selective inhibition but no effect on impulsive action selection and the patients with treatment were no more different that HC. This could explain why our medicated patients were not different from HC in late selective inhibition. However, both studies do not firmly rule out a potential role of dopamine, at least in selective inhibition and further studies are needed to clarify the role of dopaminergic therapy on cognitive action control.

The second purpose of the current study was to assess the link between impulsive action selection, suppression, and trait impulsivity, as assessed by the BIS-10 questionnaire, in both HC and patients with PD. Recent studies of HC have yielded mixed results concerning the overlap between different measures of impulsivity. Cyders and Coskunpinar, (2012) who used several tasks, including the Go/No-Go task, failed to find a link between the experimental measures and the UPPS-P impulsive behavior scale (a self-report questionnaire). By contrast, other studies have found that higher self-reported impulsivity is linked to higher error rates in Go/No-Go or antisaccade tasks [START_REF] Aichert | Associations between trait impulsivity and prepotent response inhibition[END_REF][START_REF] Reynolds | Dimensions of impulsive behavior: personality and behavioral measures[END_REF]. [START_REF] Nombela | Multiple modes of impulsivity in Parkinson's disease[END_REF] showed that, in patients with PD, BIS scores and behavioral measures yielded by a No-Go saccade paradigm or a Stroop task were part of the same factor explaining most of the variance in a principal components analysis. Furthermore, there is some electrophysiological evidence to suggest that scores on impulsivity questionnaires are related to inhibition abilities.

When [START_REF] Shen | The role of trait impulsivity in response inhibition: event-related potentials in a stop-signal task[END_REF] recorded event-related potentials during a stop task, they found that higher scores on an impulsivity questionnaire were associated with lower amplitudes of the P3 component known to be associated with successful inhibition. We hypothesized that distributional analyses are a more powerful tool for capturing this potential link, as they provide access to the fastest responses. In our patients, the highest BIS impulsivity scores were associated with the lowest accuracy. Accuracy for the first bin of the incongruent situation was correlated with both the BIS-10 total score and cognitive and motor subscores (reflecting the tendencies to making quick cognitive decisions and to act without thinking; [START_REF] Patton | Factor structure of the Barratt impulsiveness scale[END_REF]. This means that those patients who were more prone to act without thinking or to make quick decisions were the ones who displayed the most impulsive action selection in the Simon task. Furthermore, we found a negative correlation between both the BIS-10 total score and cognitive subscore and the steepness of the last delta-plot slope. Taken together, our results suggest that the patients who rated their impulsivity higher on the BIS-10 questionnaire were those who displayed the greatest impulsive action selection, as well as the strongest late selective inhibition. The fact that impulsivity revealed by the BIS scale was associated with both increased impulsivity and increased response suppression in the Simon task seems counterintuitive. One possible explanation could rely on the central role of the STN in these processes. Indeed, the STN has been involved in trait impulsivity [START_REF] Hälbig | Subthalamic deep brain stimulation and impulse control in Parkinson's disease[END_REF], Houvenaghel et al., 2016) as well as in both selection and suppression of impulsive responses (Wylie et al., 2010). It is thus possible that the impairment of the frontalsubthalamic network in PD might be reflected in both the assessment of trait impulsivity and different aspects of the experimental evaluation of action control. Beyond a common neural substrate for both increased impulsivity and increased response suppression, the concurrent correlations with the BIS score could be explained by the temporal dissociation between these two mechanisms (Wylie et al., 2010).

We found no difference in BIS-10 scores between patients and HC, in contrast to other studies where patients with PD rated it more highly than HC did [START_REF] Isaias | The relationship between impulsivity and impulse control disorders in Parkinson's disease[END_REF][START_REF] Nombela | Multiple modes of impulsivity in Parkinson's disease[END_REF]. However, the patients in these studies were older than ours, and their disease was more severe, which could explain the lack of difference we observed. While PD patients and HC were similar regarding BIS scores, strong differences appeared in the results of the Simon task, especially for impulsive action selection. These measures assess impulsivity differently:

the Simon task gives information on impulsive action selection and suppression while the BIS assesses impulsivity in a broader manner, as a personality trait. Our results suggest that impulsive action selection, measured by the Simon task, could not be detected by such a questionnaire, which does not specifically evaluates this process. Conversely, such an experimental task does not evaluate impulsivity as a personality trait. However, the correlation between the BIS scores and the results of the experimental task supported the existence of a link between these two measures of impulsivity, which had already been suggested by other authors [START_REF] Nombela | Multiple modes of impulsivity in Parkinson's disease[END_REF]. The activation-suppression model allowed us to study the dynamics of cognitive action control and proved useful in exposing this link.

However, our results do not go any way toward explaining its nature. We can only speculate that a common cause resulting from the disease influenced both our measures. Inferences on the neural mechanisms explaining this link or its impact on the performances of the patients cannot be based only on a correlation. However, this result could have interesting clinical implications. [START_REF] Nombela | Multiple modes of impulsivity in Parkinson's disease[END_REF] have reported that BIS scores and task measures, in a

Stroop task or a saccadic Go/No-Go task, were part of a same modality of impulsivity in PD patients. They further showed that this mode was correlated to a dementia rating scale.

Considering that our patients were similar to HC on BIS scores but very different at the task, one may wonder whether impulsivity related to prefronto-basal ganglia dysfunction could be first apparent in experimental measures, before its clinical expression and detection by neuropsychological tests. Experimental conflict tasks could thus help in early detection of impulsive behaviors or cognitive decline. Though highly speculative, this hypothesis could be the base for further studies investigating the links between the different types of impulsivity and their clinical implications. Considering the complexity of impulsivity, especially in PD (Robert et al., 2009), it would be relevant to assess impulsive action selection and suppression, as well as other measures of impulsivity, in PD patients with impulse control disorders and to perform longitudinal studies in PD using multiple measures of impulsivity.

Conclusion

The effect of PD on cognitive action control has been described in several studies, and in recent years, the activation-suppression model has increasingly been used to investigate the processes of impulsive selection and suppression more thoroughly. Two major results emerged from the current study. First, the combined use of an oculomotor version of the Simon task and the activation-suppression model allowed us to show that patients with PD display greater impulsive action selection, probably as the result of faster responding due to hyper-reflexive orientation of spatial attention. This hypothesis could be confirmed by directly comparing patients' performances on manual and oculomotor versions of the task.

Second, we found a correlation between an experimental impulsivity marker and a clinical scale measuring trait impulsivity. Our investigation of the dynamics of cognitive action control according to the activation-suppression model suggested that these measures share common features. However, this could be specific to our oculomotor version of the task. It would therefore be useful to check whether this link can also be found when manual versions of the task are combined with the activation-suppression model. Furthermore, the nature of this relationship needs further clarification, and more studies are needed, featuring specific impulsivity scales such as the Questionnaire for Impulsive-Compulsive Disorders in

Parkinson's disease (Weintraub et al., 2012). This would greatly help to characterize the patients and the severity of their impulsivity symptoms. It is crucial to conduct these investigations, as the impulsivity that arises from PD and/or its treatment can have a dramatic social impact.

Relevant conflicts of interest / financial disclosures:

Nothing to report

  al. have used an Eriksen flanker task (2009) then a Simon task (2010) and observed different results.

Figure 1 :

 1 Figure 1: Experimental task. Participants had to make a left or right eye movement according to the color of the target stimulus, ignoring its location. Rectangular cues flanking the fixation point held the color-response mapping constant. When the side indicated by the color matched the location of the target, the trial was congruent. When color and location did not match, the trial was incongruent.

Figure 2 :

 2 Figure 2: Mean RT (A) and accuracy (B) according to congruence and group. Error bars represent the standard error of the mean.

Figure 3 :

 3 Figure 3: CAFs for the incongruent (A) and congruent (B) situations, plotted against RT distribution, as a function of group. Error bars represent the standard error of the mean.

Figure 4 :

 4 Figure 4: Delta plots showing changes in the congruence effect (incongruent [NC] RTcongruent [C] RT) as a function of RT distribution for HC and patients with PD. Error bars represent the standard error of the mean.

Figure 5 :

 5 Figure 5: Scatterplots depicting (A) the negative correlation between the BIS total score and the accuracy rate for the first CAF bin (r = -0.38) and (B) the negative correlation between the BIS total score and the last delta-plot slope value (r = -0.36) among patients with PD.

  , while others have found no effect of PD on CAFs[START_REF] Van Wouwe | Speed pressure in conflict situations impedes inhibitory action control in Parkinson's disease[END_REF]. Another study which investigated the dynamics of cognitive action control in patients with and without their medication found no difference between PD patients and HC on impulsive action selection, whatever the patients were assessed with or without medication[START_REF] Van Wouwe | Dissociable effects of dopamine on the initial capture and the reactive inhibition of impulsive actions in Parkinson's disease[END_REF]. In the current study, the fact that patients made more fast errors in the incongruent situation than HC did argues in favor of stronger impulsive action selection in PD, as the rate of fast errors is regarded as the main indicator of susceptibility to impulsive action selection (van denWildenberg et al., 2010). Importantly, the responses of patients and HC in the first bin were equally accurate in the congruent situation, thus ruling out an attentional bias in patients.

Table 1

 1 Demographics, clinical scores and Simon task data for the PD and HC groups

		HC (n = 32)	PD (n = 32) p value
	Age (years)	55.5 (8.9)	58.7 (9.8)	0.1
	Education (years)	13.5 (2.7)	13.1 (3.2)	0.47
	Sex (M:F)	10:22	18:14	0.08
	Disease duration	-	9.5 (4.1)	-
	Hoehn and Yahr rating-ON	-	1.1 (0.8)	-
	Hoehn and Yahr rating-OFF	-	2.7 (2.3)	-
	UPDRS-motor subscore-ON	-	11.2 (8.9)	-
	UPDRS-motor subscore-OFF	-	32.3 (12)	-
	LEDD (mg)	-	995.4 (316.4) -
	MDRS	-	139.2 (3.8)	-
	BIS	45.4 (11.8)	44.3 (11.7)	0.7
	Simon task
	Congruent
	RT (ms)	416.2 (118.6) 367.2 (143.6)
	Accuracy (%)	92.7 (25.9)	90.8 (28.8)
	Incongruent
	RT (ms)	450.2 (101.7) 440.1 (123)
	Accuracy (%)	78.7 (40.9)	60.9 (48.8)
	Simon effect
	RT (ms)	34.6 (45.5)	74.4 (61.4)
	Accuracy (%)	14.3 (17.5)	28.9 (27.3)

Note. Standard deviations shown in parentheses. LEDD = levodopa equivalent daily dose.

Acknowledgements

The authors would like to thank all the volunteers who took part in this study, as well as Elizabeth Wiles-Portier who revised the English style.


Beatrice Touchelay
email: beatrice.touchelay@free.fr

Rouba Chantiri-Chaudemanche

scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Accounting normalization in

The actors, the modalities and the stages of the accountings normalization in France and in Great Britain are different. Even the meaning of normalization is different.

In France the first step to normalization is the definition of a general Chart of accounts (PCG), and then the second step is the broadcasting of that PCG. That broadcasting is spontaneous. It becomes compulsory after a long process setting different actors: companies, profession of the accountants, representatives of the fiscal administration, those of the banking circles, etc.

The definition of a PCG is strongly impulse by the State and it is imperative after the defeat, under Vichy during the Occupation between 1940 and 1944. That PCG is not compulsory before 1959, except for some enterprises and societies which benefit from fiscal advantages either which use the public savings. Its generalization to all the companies does not succeed before 1970s.

Can we think that in England the strength of the profession of the accountants, envied in France, is enough to guarantee the harmonization of the private accounting and so allows the central State to limits its interventions? The purpose of our research project financed by the to answer to that question.

We want to precise characteristics of those two models, the English and the French, and to analyze their functioning and their effect, as long about the organization of the economy or the company, that on the respective performances of these two countries in term of economic growth and political and social dialogue. The question arises with all the more acuteness as this originality dissolves in the IASB today, the French model doubtless more has to loose in this standardization because it distinguishes itself more from the international frame. But how to explain that it does not find best defenses to press on the decisions which condemn it widely? To what extent their histories, the diversity of its stakeholders contribute them to its fragility? We have to try to answer to that question by a comparison between French and English models.

The role of the profession of the accountants, that of the representatives of the employers, that of the businessmen and also that of the opinion in general, which shows itself through the press in front of the will of the State to harmonize the private accountings are going to be questioned in two different national configurations, in France and in Great Britain. Indeed, if the State impulse which shows itself through institutions to define the PCG, then to adapt it to the needs for companies and for the State adorned dominant in France its methods remain to specify. The set of the French actors is to be compared with those of the normalization in Great Britain.

What are the components of this impulse? Is the respective role of taxes, of different ministries? How do the institutions of accounting regulation get organized and to what extent they let express themselves differences? Can we say that the PCG and its adaptations result from a consensus? What are the arguments of the different protagonists?

So many questions in which we thus try to answer by going back to the origins of the normalization in France and by beginning more late, in the 1970s for Great Britain, moment when the process is at the same stage in both nations. To know to what extent the English and

French accouting normalization was able to play a driving role in the Trente Glorieuse and to wonder about its possible contribution to the slowing down of growth, the in the crises of the end of the XX th century and finally on its relations with the liberal bend of the last thirty years in another objective of our subject.

It is a question of knowing in which title (experts, representatives, consultants) the actors intervene and there to reconstitute a sequence of formation of the expertise of the accountants.

State regulation or self regulation, two models?

The French case: the central role of the State Before 1940:

The definition of the accounting profession is very slow in France. Political, economic and social elites are not interested by accountancy. Most of them are indifferent, even hostile to the development of the private accounting. The place of formation of these elite (faculties of Law and Ecole libre de sciences politiques for exemple) are not opened to the accounting teaching. The will to defend the secret of business is very strong.

Chartered accountant s certificate introduced in 1927 gets ready for the National Conservatory of Arts and Crafts (CNAM in Paris), which is an institution dedicated to the continuing education and rather directed to the technical education. In France during the interwar period the expertise is not always pressed on the rational calculation but frequently based on the intuition.

The financial scandals, the needs for accounting information of banks then for taxes favor the propaganda of the accountants who wish to organize their profession but the legislation does not support this movement. The late regulations of the commissaires aux comptes in 1935 testify of this lack of support: no chartered accountants diploma is required to become statutory auditor.

The break of the Occupation and the birth of a chartered accountancy

The accounting profession and the PCG are imperative at the same moment, thanks to an exceptional situation. Indeed, the defeat, the armistice and the putting places of a new political A second factor is « structural ». The Chart of accounts remains optional because companies, especially small sized and medium sized, would doubtless have a hard job if it was necessary to them to apply it. The weakness of the formation of the managers and the business executives, the crumbling of the activities and the insufficiency of the number of the accountants slow down the normalization.

The third factor is the one of the absence of sufficient political will to oppose the traditional positions of the employers which is little favorable to the normalization. Labor unions are not very interested in these debates. The leading players, the Stet, the employers and the accountants are inclined in favor of to let make till the end of 1950s.

Balance : a long process of normalization

The change of Republic is convenient to the obligation. The budgetary constraints and the strong growth of the economic activity as the labor-union calm explain the decision of 1959.

This decision entrusts to the different employers organizations of business sectors the care of adapting the last PCG (1957) to capacities and to needs of the profession. The small affairs and the storekeepers are very slow to adapt their practices; they take more than ten years

The employer represented by the CNPF (Conseil National du Patronat Français) is divided.

A part signs its attachment in let make (the liberal charter of 1963) and another one accepts

Before 1970

Accounting regulations are included, since 1844, in the company law, the Companies Act.

The Companies Act has been revised at several occasions since 1844. A notable revision occurred in 1947. The main new requirements are numerous additional information, the specification of the content of the audit report as well as the replacement of the notion of true and correct by that of true and fair view.

Although the Companies Act has been revised since then, the main accounting requirements in force in 1970 were already included in the consolidated Companies Act of 1948, which replaced all existing acts.

The accounting requirements defined in the law remained however very general, as is traditionally the case in a country of common law. The law specifies the minimal information to be communicated and contains few rules regarding measurement and presentation. For instance, no precise formats for balance sheet and profit and loss accounts were defined nor detailed measurement rules were specified. The law expressed a general obligation, that the annual accounts give a true and fair view of reality. This true and fair view was then considered as an overriding principle in case of contradiction with other legal requirements. It has been presented as a meta-principle, orienting the establishment of accounting information.

In this context, the professional judgment was considered as a fundamental feature of the process. The accountant and, more specifically the auditor, have to exercise their judgment and appreciate, according to the circumstances, if the accounts reflect faithfully reality.

The system thus rested on very general rules contained in the law and on the professional judgment of the accountant. There were no so to speak accounting standards within a body appointed for that purpose.

The Institute of Chartered Accountants in England and Wales (ICAEW) issued since the 1940s recommendations, as good accounting practice, on certain litigious issues. These recommendations, intended at the institute s members, were not compulsory. Other institutes, like the Institute of Chartered Accountants of Scotland (ICAS) did not consider necessary to develop guidelines, leaning on a tradition that gives primacy to the professional judgment of the auditor.

This situation was going to be questioned, at the end of 1960s. Indeed, the development of mergers and acquisitions gave rise to several scandals (AEI-GEC, Pergamon-Leasco) bringing to light the effects of flexible regulations : numerous options, a level of income that varies according to the principles applied and accounts that mislead the user of accounts instead of depicting fairly reality.

Considerable criticism developed towards accounting practices, towards the current regulatory system and towards the accounting profession. The press echoed these criticisms.

The climax was reached when Professor Edward Stamp asked, in the columns of The Times, for change and reform and was answered by the president of the ICAEW at that time, Sir Ronald Leach, defending the status quo.

Accounting standard-setting under the aegis of the ASC (1970-1990)

The ASC was set up with a mission to develop accounting standards to be submitted to the professional institutes that form the Consultative Committee of Accounting Bodies (CCAB).

The responsibility for publishing the standards rested on the CCAB. The standards were called Standard Statement of Accounting Practice (SSAP). 25 SSAP were adopted between 1970 an 1990.

The standards adopted were compulsory only for the members of the institutes but the action of these members allowed to ensure a wide application.

The ASC was a committee formed by about twenty part-time, voluntary members, coming, at the beginning from the professional institutes. With the passing of time and following recommendations formulated by working groups established to suggest improvement of the system, the membership was widened to include a few non accountant members. Besides, observers representing public authorities attended the meetings of the ASC.

Following are some features of the process of setting standards within the ASC. Projects were prepared within working groups, associating members of the ASC, members of accounting institutes as well as people, not belonging to the accounting profession but skilled on the considered problem. The working group delivered its conclusions to the ASC. The ASC sometimes asked for additional work. After an iterative process, the ASC adopted a standard.

The standard was then submitted to the CCAB for approval. In fact, a standard was to be approved by each of the six institutes forming the CCAB. Numerous deadlocks resulted from what could be considered as a right of veto, one of the organizations refusing to accept a draft endorsed by the others.

The ASC had few resources available, either financial or human. In particular, the secretariat and the technical team included only a small number of people, partly on a part-time basis.

The offices of the ASC were hosted in the premises of the ICAEW.

In that sense, accounting standard-setting was handled by the accounting profession.

However, some studies have shown that contacts were established between the accounting profession and public authorities and that the latter followed indirectly the setting of accounting standards.

The debate over inflation accounting offered an opportunity for the State to play an explicit role. The ASC published an exposure-draft of the subject in 1973. Shortly after, the government decided to set up, independently from the ASC and by-passing the accounting profession, a committee in charge of making proposals on this issue (Inflation Accounting Committee, named Sandilands Committee after its chairman). The Sandilands Committee published a report in 1975 recommending the implementation of replacement cost accounting for all companies. The accounting profession reluctantly agreed the proposals and the ASC was in charge of translating replacement cost into a standard. The process was long and tortuous. The standard Current cost accounting (SSAP 16) was published finally in 1980, not without some compromises. Widely applied at first, it was gradually abandoned without any sanction. In 1988, the CCAB removed this standard. For Robson (1994), this episode is an illustration of the State acting at a distance .

The second decade of the ASC s life was progressively dominated by questions about its role and authority. The main criticisms were directed towards the length of the process, the poor resources of the ASC, the dependence upon the accounting profession, inconsistencies between standards, the authority and the implementation of standards Although some working groups were formed to make proposals for improving the system and its organization, the improvements introduced did not cut short the virulent criticisms.

To counter the increasing criticisms at the end of the 1980, a committee was formed with the mission of making proposals regarding the form and the authority of standards as well as the institutional structure, the role of public authorities and the role of law. The Dearing committee, as it was named after its chairman, drove many consultations with various interested parties before formulating proposals which led to a thorough reform of the system.

Although the reform is comes outside our period of study, it is worth describing its main features in that enables to illustrate a profound change in the role of the State.

Reforming the standard-setting institutions in 1990

Ronald Dearing, who became after Lord Dearing, was the chairman of the committee in charge of formulating proposals for the organization of standard-setting in Great Britain. It is worth detailing some features of Ronald Dearing s professional background.

Former senior civil servant of the Department of Trade andIndustry, Ronald Dearing (1930-2009) is used to crisis situations. Before chairing the committee in charge of formulating recommendations regarding accounting standard-setting, he was chairman and chief executive of the British Post Office (1981)(1982)(1983)(1984)(1985)(1986)(1987) while the company went through a difficult period. He also chaired, in the early 1990s, a committee in charge of formulating proposals regarding the higher education and advised the government in this field.

As far as accounting standard-setting is concerned, the proposals formulated by the Dearing committee were nearly all adopted. One of the main features was keeping accounting standard-setting in the realm of the private sector but supported not only by the accounting profession but by the whole accounting and financial community. The institutions that were set are very similar to the American standard-setting institutions in place since 1973.

Although in the private sector, some elements reinforce the role of the State and of the law.

According to the Dearing Report, the role of government should be that of « facilitator ». A number of measures were introduced in the Companies Act in order to reinforce the authority of accounting standards; for instance, the recognition, in the law, of accounting standards provided, for the first time, a legal recognition to standards. Besides, the government provided a substantial financial contribution: the Department of Trade and Industry contributed to one third of the budget, equally to the participation of the accounting profession (through the CCAB) and to that of the financial and banking community (through mainly the Stock Exchange).

Conclusion

Three stages emerge from the previous analysis :

A stage of no institutional standard-setting (before 1970): accounting regulation is oriented by very few prescriptions in the law and the importance of professional judgment in relation with the true and fair view;

A stage of standard-setting organized by the accounting profession : standardsetting is in the hand of the accounting institutes (financing, membership).

The involvement of the State and the authority of law begin only to be formalized after 1990.

Therefore, for a long time, accounting regulation was in the hands of the profession, being considered as self-regulation. Accounting institutes and the accounting profession includes accountants in firms as well as accountants working for companies or in the public sector.

The British case is a typical example of the Anglo-Saxon tradition of accounting standardsetting where accounting matters are entrusted to the accounting profession. Because they deal, on a daily basis, with accounting issues, accountants, either in firms, in companies or in universities, are the best suited to the task of developing standards and of tackling the increasing complexity of the problems to be handled.

The role of the State in organizing the setting of accounting rules is therefore reduced in Great Britain. However, from the years 1980-1990, increasing awareness of the political dimension of accounting standards and their impact on the distribution of wealth forced mentalities to change and to consider accounting standards as a matter of public policy where the State has a role to play as a facilitator .

Comparison with France, and also with Germany, have to be develop to definite the future of accounting.

Bibliographie

  France since the First World War and in Great-Britain during the 1970-1980's, a first step to a comparative analysis. Actors and limits of the institutionalization of the accounting normalization in France and in Great Britain, crossed approach Béatrice Touchelay, Rouba Chantiri-Chaudemanche To cite this version: Béatrice Touchelay, Rouba Chantiri-Chaudemanche. Accounting normalization in France since the First World War and in Great-Britain during the 1970-1980's, a first step to a comparative analysis. Actors and limits of the institutionalization of the accounting normalization in France and in Great Britain, crossed approach. 1st World Conference of Business History, Mar 2014, Frankfurt, Germany. pp.11. hal-01505367

Figure 1 .

 1 Figure 1. Source. Bulletin de l ordre des experts comptables et des comptables agréés The executive positions of the Order become elective and the weight of the State on the profession is reduced. Let us note however that the State protects a right to inspect the profession and the evolution of the Chart of accounts: government Commissioner endowed with powers not insignificant (fees or promotions for example) is attached to the Upper Council of the Order; the composition, of the National Council of the accounting asked to adapt the PCG to the economic needs, reserves a wide place to the representatives of the ministerial directions, finally the State maintains control over the training and the diplomas.The accounting normalization under the control of the State in FranceParadoxally, while in France the Reconstruction comes along with large-scale structural reforms which mark the assertion of the State as economic and social actor and while the politics of frame of the economic activity confirms during the Fourths Republic (nationalizations, planning, National accounting, etc), it is necessary to wait for 1959 so that an article of the law of finance envisages the generalization of the Chart of account. How can we explain this contradiction ? A first factor holds the disappearance of the profession of the French chartered accountants which is obvious till the end of 1950s. It holds the small number of chartered accountants and the average level of qualification in accounting.

Figure 2 .

 2 Figure 2. Source. Bulletin de l ordre des experts comptables et des comptables agréésThe profession answers with difficulties the scale of the needs for companies confronted with the inflation and with complexity of taxes. 1950s are the period of the Comptables ambulants who cross the country and hold the accounting of craftsmen and storekeepers behind their small vans. They are also the one accountant s generations for which the accounting is a real factor of upward social mobility. Little sure of herself even, the profession plays only a role erased in the definition of the PCG and opposes even any shape of certification of balance sheets.

  more the supervision of the State (industrial inventory of 1963 attempt of incomes policy). It does not rebel when the decree of 1965 obliges to follow the prescriptions of the PCG of 1957 to declare their profits. The accounting profession gets involved in the debates through the Comité de Diligence Comptable organized by Robert Mazars who testifies of a real change of generation. The profession tries to take its fate in hand and the tensions with government Commissioner are more and more lively. At the end of 1960s, the normalization was imperative. A new period is opened which is the one of the cooperation of the employers, the accountants and of the State. Years 1970-1980 open another period, are they announcing the end of the French model and the generalization of the Anglo-Saxon model? The British case : self regulation by the accounting profession It would seem that the history of accounting standard-setting in Great Britain begins only in 1970 with the creation by the institutes of chartered accountants of a committee in charge of developing accounting standards, the Accounting Standards Steering Committee (ASSC), renamed Accounting Standards Committee (ASC) in 1975. There was, strictly speaking, no accounting standard-setting organization before 1970.

  The growing criticism and calling into question within the profession led the ICAEW to react by publishing in 1969 a statement of intention, followed by the creation in 1970 of the Accounting Standards Steering Committee (ASSC) in charge of developing accounting standards. The Scottish and Irish Institutes (Institute of Chartered Accountants of Scotland (ICAS) and Institute of Chartered Accountants of Ireland (ICAI)), joined the ICAEW to this initiative, followed by the Chartered Association of Certified Accountants (CACA) and the Chartered Institute of Management Accountants (CIMA) in 1971 and by the Chartered Institute of Public Finance and Accountancy (CIPFA) in 1976. Therefore, the ASC was "sponsored" by six professional institutes that formed the Consultative Committee of Accounting Bodies (C.C.A.B.).

  Leach R., Stamp E. (coord) (1981), British accounting Standards: the first ten years, Woodhead-Faulkner. McBarnet D., WhelanC.J. (1992), « Regulating accounting: limits in the law » in Accounting and the law, coord. by M. Bromwich et A. Hopwood, Prentice Hall/ICAEW, pp. 99-111. Patient M. (1992), « The relationship between accounting and the law from the professional accountant s perspective » in Accounting and the law, coord. by M. Bromwich et A. Hopwood, Prentice Hall/ICAEW, pp. 15-29. Pong C. and Whittington G. (1996), « The withdrawal of current cost accounting in the United Kingdom: a study of the Accounting Standards Committee », Abacus, vol. 32, n° 1, pp. 30-53 Robson K. (1994), « Inflation accounting and action at a distance: the Sandilands episode », Accounting, Organizations and Society, vol. 19, n° 1, pp. 45-82. Touchelay B., L Etat et l entreprise. Une histoire de la normalisation comptable et fiscale à la française, Rennes, PUR, 2011.