International audience Schizophrenia, particularly auditory verbal hallucinations (AVH), has been associated with impairments in source monitoring where patients tend to misattribute the source of an internal speech event to an external agent. Previous research has proposed that abnormalities in generating thoughts induce more vivid auditory sensations in schizophrenia patients through a failure of corollary discharge between the frontal and the temporal cortices (Frith, 1996). The patients are able to generate willed actions but cannot control the intentions behind it and therefore experience them as originating from an external source. This could account for source attribution errors, and at a higher threshold, could lead to AVH. In the present study, we investigated the neural underpinnings of a verbal thought generation (VTG) task using fMRI in 5 schizophrenia patients (DSM-IV; mean age = 33.8; sd= 7.53) and in 12 healthy controls (mean age = 25.9; sd= 7.08). The study sought to investigate the patterns of cerebral activation associated with generating thoughts in schizophrenia patients. Methods: Two conditions were examined. In the first condition, participants were required to mentally generate a definition of a common word presented on the screen. In the second condition, they had to listen to the definition of a common word presented on the screen. An event-related fMRI protocol was used during two 9.25 minute scanning sessions in a 3T scanner. Results: Statistical analyses were performed using constrained principal component analysis (CPCA) with a finite impulse response (FIR) model. During the mental generation task, activations (task-positive network) were observed for both groups in the anterior cingulate (BA 32) and in the left prefrontal (BA 47) gyri, while deactivations (task-negative network) included the posterior cingulate cortex (BA 31), the medial frontal gyrus bilaterally (BA10), and the bilateral angular gyrus (BA 39, 40). Importantly, this network showed less activation of the task-positive and more deactivation of the task-negative networks in schizophrenia patients relative to healthy controls. On the contrary, no group differences were detected in the listening only condition, with activations found within auditory superior temporal and dorsolateral frontal regions in both groups. Discussion: These results suggest abnormalities in task-positive and task-negative networks associated with the generation of thoughts in schizophrenia, but these abnormalities were not found during listening. Given the hypothesized role of the above-mentioned regions in internal speech and self attributed mental processes (Buckner et al., 2008), these abnormalities might result in self referential misattribution which may play a part in the genesis of auditory verbal hallucinations.