Prefrontal-posterior parietal networks in schizophrenia: primary dysfunctions and secondary compensations.
|Title||Prefrontal-posterior parietal networks in schizophrenia: primary dysfunctions and secondary compensations.|
|Publication Type||Journal Article|
|Year of Publication||2003|
|Authors||Quintana, J, Wong T, Ortiz-Portillo E, Kovalik E, Davidson T, Marder SR, Mazziotta JC|
|Date Published||2003 Jan 1|
|Keywords||Adult, Affect, Cognition Disorders, Cues, Female, Humans, Logic, Magnetic Resonance Imaging, Male, Memory Disorders, Nerve Net, Parietal Lobe, Prefrontal Cortex, Reaction Time, Schizophrenia|
Working memory (WM) deficits are well known in schizophrenia and have been associated with abnormal activation patterns of the prefrontal cortex (PFC) during cognitive performance. The magnitude and particularly the direction of the PFC activation -- i.e., increased (hyperfrontality) or decreased (hypofrontality) -- in schizophrenia, as well as its pathophysiological implications, remain controversial. Working memory is supported by a distributed neural network, whose main components are the PFC and the posterior parietal (PPC) cortices. Monkey studies indicate that, during WM performance, PFC functional lesions may be compensated by the PPC if task demands center mainly on anticipating responses, but not if they center on remembering cues. We hypothesized that a primarily dysfunctional PFC in schizophrenia might show hypofrontality or hyperfrontality as a result, respectively, of efficient or inefficient PPC compensation, as dictated by task demands. To test our proposition, we biased the demands of WM tasks toward anticipating responses or remembering cues and measured its impact on the PFC-PPC functional balance in a group of schizophrenic patients and one of normal control subjects.
|Alternate Journal||Biol. Psychiatry|