Dominance of Objects over Context in a Mediotemporal Lobe Model of Schizophrenia

Background: A large body of evidence suggests impaired context processing in schizophrenia. Here we propose that this impairment arises from defective integration of mediotemporal ‘what ’ and ‘where ’ routes, carrying object and spatial information to the hippocampus. Methodology and Findings: We have previously shown, in a mediotemporal lobe (MTL) model, that the abnormal connectivity between MTL regions observed in schizophrenia can explain the episodic memory deficits associated with the disorder. Here we show that the same neuropathology leads to several context processing deficits observed in patients with schizophrenia: 1) failure to choose subordinate stimuli over dominant ones when the former fit the context, 2) decreased contextual constraints in memory retrieval, as reflected in increased false alarm rates and 3) impaired retrieval of contextual information in source monitoring. Model analyses show that these deficits occur because the ‘schizophrenic MTL ’ forms fragmented episodic representations, in which objects are overrepresented at the expense of spatial contextual information. Conclusions and Significance: These findings highlight the importance of MTL neuropathology in schizophrenia, demonstrating that it may underlie a broad spectrum of deficits, including context processing and memory impairments. It is argued that these processing deficits may contribute to central schizophrenia symptoms such as contextuall

Les orientations actuelles de la recherche psychiatrique en France

RésuméL’intérêt pour la recherche connaît, depuis une dizaine d’années, un grand développement au sein de la communauté psychiatrique française. Ceci est dû en grande partie à une politique volontariste des organismes publiques de recherche et tout particulièrement de l’Institut National de la Santé et de la Recherche Médicale (INSERM). Un inventaire des actions spécifiques en faveur de la recherche psychiatrique est dressé.Un panorama des principaux axes de recherche est ensuite brossé. Certaines lacunes sont ensuite soulignées : méthodologie de l’évaluation des soins, toxicomanie, recherche sur les psychothérapies.Des suggestions sont ensuite proposées en vue de maintenir ce développement : formation à la recherche, structures coopératives en réseaux intéressant les différents secteurs de la profession. Un danger doit être dénoncé : celui d’un hiatus entre la recherche articulée avec la biologie et celle articulée avec les sciences humaines et sociales.</jats:p

Decision Time and Movement Time: Differential Effects of Practice

Choice Reaction Time involves at least two components of response latency, Decision Time and Movement Time. Studies usually report values for these two components averaged over a definite number of trials. The aims of this study were to investigate the pattern of behaviour of the two components across the trials and the effect of repeating the experimental procedure two weeks later. 16 control subjects were given two sessions of 50 trials each. In Session 1 (D.0), the two components behave quite differently across the trials; there was no significant change in decision time, but a significant reduction in movement time occurred. Decision and movement time show no relationship. In Session 2 (D.15), a different pattern was found; movement time was still significantly reduced across trials but there was also a significant increase in decision time so the two components exhibit a negative relationship. Comparison of values from Sessions 1 and 2 shows an effect is found only on the first 10 trials for both components, the values of decision and movement times being smaller in Session 2 than Session 1. </jats:p