F85. DISRUPTION OF POSTERIOR PARIETAL CORTEX AND STRIATUM DURING SPATIAL WORKING MEMORY IN SCHIZOPHRENIA AND BIPOLAR DISORDER. (9th April 2019)

• Record Type: Journal Article
• Authors: Huang, Anna; Rogers, Baxter; Woodward, Neil
• Is Part Of: Schizophrenia bulletin. Volume 45(2019)Supplement 2
• Page Start: S286
• Page End: S286
• Publication Date: 2019-04-09
• Subjects: Schizophrenia -- Periodicals; Schizophrenia -- Research -- Periodicals; 616.898005
• DOI: 10.1093/schbul/sbz018.497
• Languages: English
• ISSNs: 0586-7614

Abstract

Abstract: Background: Working memory (WM) is impaired in schizophrenia and bipolar disorder and often attributed to dorsolateral prefrontal cortex (BA 9/46) dysfunction. However, the frequent use of tasks like the N-back that place high demands on executive processes, in addition to component WM processes such as encoding and maintenance, and recent findings in schizophrenia linking WM impairment to posterior parietal cortex (PPC) dysfunction challenge this conclusion. The current investigation examined brain function during performance of a spatial delayed match-to-sample task to: 1) characterize neural responses during specific stages of WM; and 2) determine whether schizophrenia and bipolar disorder show similar abnormalities in brain function during WM. Methods: We scanned 58 healthy individuals (CON), 73 individuals with schizophrenia (SCZ) and 41 individuals with bipolar I disorder with psychotic features (BPD) in a functional magnetic resonance imaging scanner while they performed a slow event-related spatial delayed match-to-sample task with a long delay (16 s). We investigated between group differences in BOLD responses during the encoding, early delay, late delay and probe phases of the task. Results: During encoding, CON group showed greater activation in bilateral superior parietal lobule compared to SCZ and BPD groups. Bilateral superior parietal lobule activation was positively associated with performance (greater activation was associated with greater d'). The right striatum also showed significant differences between groups during encoding such that the SCZ group showed lower activation than the CON and BPD groups. Striatal activation was correlated with negative symptoms in patients; lower striatal activation was associated with more severe negative symptoms. During the late delay period, the CON group showed greater activation in the left frontal eye field compared to the SCZ and BPD groups. Discussion: We found that schizophrenia and bipolar disorder showed similar impairments in the PPC, with this activation significantly associated with performance, suggesting that PPC function is important to working memory impairment in both schizophrenia and bipolar disorder. Unexpectedly, we found that striatal activity differentiated schizophrenia and bipolar disorder groups during WM. Further investigation of striatal activation during working memory may be important for understanding differences between schizophrenia and bipolar disorder in the neural substrates underlying cognition.