No abstract

Context: Memory is one of the cognitive functions most affected in schizophrenia, with deficits observed from the first episode of psychosis (FEP). Previous studies have indicated that some memory processes may be more affected than others.Objective: To examine the neural correlates of 3 specific memory processes in FEP by means of functional magnetic resonance imaging (fMRI).Design: Case-control study. Main Outcome Measures:Behavioral performance and regional brain activity measured during memory encoding by fMRI. Our fMRI design included 3 within-subject contrasts (associative vs item-oriented encoding, encoding of arbitrary vs semantically related image pairs, and successful vs unsuccessful memory encoding) that were then used for group conjunctions and between-group analyses.Results: Patients with FEP showed normal activation of several brain regions, including the prefrontal cortex, hippocampus, and parahippocampal cortex, during successful memory encoding and associative encoding. In contrast, the hippocampus and surrounding medial temporal areas showed reduced activity during the encoding of arbitrary pairs. This selective dysfunction reflected by abnormal brain activation during encoding was accompanied by a greater deficit for subsequent recognition of arbitrary pairs relative to the semantically related pairs.Conclusions: This study demonstrated that, in the same group of patients with FEP, the hippocampus could show either normal or abnormal modulation of activation depending on the specific cognitive process that was examined. The normal modulation of hippocampal activation observed during successful memory encoding in FEP argues against a general inability to recruit this region. Instead, the dysfunction was specifically linked to semantic relatedness. This selective deficit seems to affect memory performance in FEP and denotes an important representational problem that may confer greater vulnerability to psychotic disorders and would thus be interesting to examine in high-risk populations. Psychiatry. 2007;64(9):999-1014 Arch Gen

Several studies have demonstrated that patients with schizophrenia show impairments in social cognition and current evidence indicate that this deficit is associated with abnormal activity in specific brain regions. In addition to functional imaging studies, we believe that the identification of structural correlates of social cognitive processes may help to better understand the neural underpinnings of these specific skills. The main objective of this study was to investigate the relationship between gray matter density and social cognitive deficits in first episode of schizophrenia spectrum psychosis, using a comprehensive assessment that we previously demonstrated to be a highly sensitive measure of social cognitive deficits in this population. Thirty-eight patients with a first episode of psychosis participated in this study, and the Four Factor Test of Social Intelligence was used as a measure of social cognition. Social cognitive impairments in first episode psychosis were significantly correlated with reduced gray-matter density in the left middle frontal gyrus other regions within the mirror neuron system network (MSN), namely the right supplementary motor cortex, the left superior temporal gyrus and the left inferior parietal lobule. We concluded that structural abnormalities within the MSN may account for the social cognitive deficits present in some psychiatric disorders, such as schizophrenia.