Hélène Wilquin

A ticking clock for the production of sequential actions: Where does the problem lie in schizophrenia?☆

Schizophrenia has been associated to a distorted time clock. By subtracting contact duration from Inter Response Interval, we report evidence for preserved internal clock in schizophrenia, with normal spontaneous tapping tempo. Contact durations were however increased in patients suggesting a specific problem in the fast integration of incoming haptic feedback with outgoing motor efferences. This integration deficit would emerge at an early phase, since Ultra High Risk patients also revealed abnormal tapping stability. Tactile screens revealed to be a simple and low cost apparatus that may constitute a suitable measuring kit for the characterisation of sensory motor deficits in clinical settings.

Combined visual and motor disorganization in patients with schizophrenia

Cognitive impairments are difficult to relate to clinical symptoms in schizophrenia, partly due to insufficient knowledge on how cognitive impairments interact with one another. Here, we devised a new sequential pointing task requiring both visual organization and motor sequencing. Six circles were presented simultaneously on a touch screen around a fixation point. Participants pointed with the finger each circle one after the other, in synchrony with auditory tones. We used an alternating rhythmic 300/600 ms pattern so that participants performed pairs of taps separated by short intervals of 300 ms. Visual organization was manipulated by using line-segments that grouped the circles two by two, yielding three pairs of connected circles, and three pairs of unconnected circles that belonged to different pairs. This led to three experimental conditions. In the “congruent condition,” the pairs of taps had to be executed on circles grouped by connecters. In the “non congruent condition,” they were to be executed on the unconnected circles that belonged to different pairs. In a neutral condition, there were no connecters. Twenty two patients with schizophrenia with mild symptoms and 22 control participants performed a series of 30 taps in each condition. Tap pairs were counted as errors when the produced rhythm was inverted (expected rhythm 600/300 = 2; inversed rhythm <1). Error rates in patients with a high level of clinical disorganization were significantly higher in the non-congruent condition than in the two other conditions, contrary to controls and the remaining patients. The tap-tone asynchrony increased in the presence of connecters in both patient groups, but not in the controls. Patients appeared not to integrate the visual organization during the planning phase of action, leading to a large difficulty during motor execution, especially in those patients revealing difficulties in visual organization. Visual motor tapping tasks may help detect those subgroups of patients.

Production de rythmes dans la schizophrénie : rôle central de l’attention

BACKGROUND Schizophrenia is a psychiatric illness that is characterised by a deficit in the fluent sequencing of thought and action. This problem of discoordination might be due to unreliable timing processes associated with a difficulty in allocating sufficient attention. In the present study, we placed ourselves within the hypothesis that schizophrenic patients may have difficulties in producing rhythmic tapping actions and that this deficit may be correlated with the degree of attention abnormalities. METHOD Subjects were required to tap in rhythm with alternating force levels and/or alternating time intervals (<1s) during trials lasting 24s. In addition, all patients performed an attention task (D2 test). A qualitative analysis of the tap trials was conducted in order to characterise the nature of the deficits that patients revealed. RESULTS Results showed that all patients revealed significant difficulties in performing the tapping trials. The number of trials removed was correlated with the level of attention dysfunction. Finally, our qualitative analysis revealed that 60% of patients presented attentional lapses - which were never observed in the healthy controls. CONCLUSION This study revealed deficits in the timing of action that resemble, at least on a behaviour level, the clinical lapses observed in schizophrenia. These lapses seem to be correlated to the degree of attention deficits. Future studies are now required in order to gain better understanding of the nature of the attention deficits in schizophrenia. More specifically, a better definition of the possible functional relationship between clinical lapses, cognitive lapses and action freezing is needed to develop innovating tools for rehabilitation.

Predictive Timing for Rhythmic Motor Actions in Schizophrenia

Time is a common word, used frequently in our everyday language. It appears in many expressions: “I killed time playing cards,” “Lets take time to talk,” “I did two things at the same time.” However, even if used by all, the word Time refers back to a complex phenomenon that is difficult – even impossible – to define. To this a priori simple question: “What is time?” the theologist Saint Augustin answered: “If no one asks, I well know; but if someone poses me the question, and I try to reveal my thoughts, I realise that I in fact do not know” (Les Confessions de Saint Augustin, Livre xxi, chapitre xiv, traduit de Moreau, 1864, édition 1942). Time has the ineffable character that reveals its existence only through a construct of the mind (Kant, 1845). Hence, Kants’ understanding of Time infers two distinct phenomena: a physical absolute time and the psychological subjective time, the later being the only one sensitive to a distorted mind. The physical time, encapsulated in the real number “t,” would correspond to that defined by Newton as Absolute Time: “Absolute time, without reference to anything external, flows uniformly” (1726 (1987), p. 408). Two concepts are here involved: absolute equality of time intervals (“uniform flow”) and less obviously but equal essentially, absolute simultaneity, which is the more pervasive concept that underlies not only physics, but also the notion of past, present, and future. As such, the laws of physics impose to Time the idea of causality with the impossibility to act upon the past (i.e., to modulate events that have already taken place). The causality postulate may be one of the reasons why psychologists have revealed more interest in the study of Subjective time. The question being: “How does a subject experience the passage of Time? What is the experience of my own body as an actor in the past causing the occurrence of an event in the present time? Why can I, under certain situations, lose track of time with

Poster #236 LISTENERS IMPRESSIONS OF SPEAKERS WITH SCHIZOPHRENIA: IMPACT FOR SOCIAL FUNCTIONING

Individuals with schizophrenia show impairment in everyday verbal communication which may contribute to their social isolation. Social cognition including theory of mind, emotion processing and social perception (Couture et al., 2006) plays a critical role in social interaction, particularly in language communication (Champagne-Lavau et al., 2006; 2009). Impairment of social cognition may result in social dysfunction, at the social, school and professional levels (Fett et al., 2010). Several studies have showed impairments in social cognition in schizophrenia, using perception and comprehension paradigms in most cases. However, to our knowledge, no studies have looked at how speech patterns in schizophrenia contribute to linguistic and social impressions formed about individual with schizophrenia from the perspective of listeners. Thus, the aim of this research was twofold: Firstly, to determine whether speech and discourse content produced by individuals with schizophrenia contribute to the negative social impression experienced by people regarding schizophrenia; secondly to assess what criteria (prosodic and/or discourse content) are likely to generate this negative impression.