Phase-specific brain change of spatial working memory processing in genetic and ultra-high risk groups of schizophrenia.

Spatial working memory (WM) processing has 3 distinct phases: encoding, maintenance, and retrieval and its dysfunction is a core feature in schizophrenia. We examined phase-specific brain activations associated with spatial WM in first-degree relatives of schizophrenia (genetic high risk, GHR), ultra-high risk (UHR) subjects, patients with schizophrenia, and healthy controls. We used an event-related functional magnetic resonance imaging in 17 GHR subjects, 21 UHR subjects, 15 clinically stable patients with schizophrenia and 16 healthy controls, while subjects were performing a spatial delayed-response task. During the encoding phase, the GHR group showed increased activation in the fronto-parietal regions, whereas the UHR and schizophrenia groups showed significantly less activation in these regions than did the healthy control group. Especially, frontal activation was strongest in GHR subjects, followed by healthy controls, and occurred to a lesser degree in the UHR group, with the least activation occurring in the schizophrenia group. During the maintenance phase, the thalamus showed a differential activation, similar to frontal activation pattern during the encoding phase. During the retrieval phase, no prominent differential activations were found. Increased activations were observed in the superior temporal gyrus during the encoding and maintenance phases in the GHR, UHR, and schizophrenia groups relative to healthy controls. Our findings suggest that functional deficits associated with spatial WM processing emerge in the UHR before the onset of schizophrenia and compensatory neural processes exist in the GHR with genetic liability to schizophrenia.

Thalamus surface shape deformity in obsessive-compulsive disorder and schizophrenia.

The authors performed a three-dimensional shape deformation analysis to clarify the various patterns of specific thalamic nuclei abnormality using three age-matched and sex-matched groups of 22 patients with obsessive-compulsive disorder (OCD), 22 patients with schizophrenia and 22 control participants. Compared with the healthy volunteers, the anterior, lateral outward surface deformities of the thalamus were significant in OCD patients, whereas the posterior, medial outward deformities of the thalamus were prominent in schizophrenia patients. In terms of thalamic asymmetry, both OCD and schizophrenia patients exhibited the loss of a leftward pattern of asymmetry on the posterior, medial surface of the thalamus. Different patterns of shape abnormality of specific thalamic nuclei may be related to the different phenomenology of OCD and schizophrenia.