Perceptual closure is the ability to identify objects based on partial information and depends on the function of a distributed network of brain regions that include the dorsal and the ventral visual streams, prefrontal cortex (PFC), and hippocampus.
To evaluate network-level interactions during perceptual closure in schizophrenia using parallel event-related potential (ERP), functional magnetic resonance imaging (fMRI), and neuropsychological assessment.
Inpatient and outpatient facilities associated with the Nathan Kline Institute for Psychiatric Research.
Twenty-seven patients with schizophrenia or schizoaffective disorder and 23 healthy controls.
Event-related potentials were obtained from 24 patients and 20 healthy volunteers in response to fragmented (closeable) and control-scrambled (noncloseable) line drawings. Functional MRI was performed in 11 patients and 12 controls.
Main Outcome Measure
Patterns of between-group differences for predefined ERP components and fMRI regions of interest were determined using both analysis of variance and structural equation modeling. Global neuropsychological performance was assessed using standard neuropsychological batteries.
Patients showed impaired generation of event-related components reflecting early sensory and later closure-related activity. In fMRI, patients showed impaired activation of the dorsal and ventral visual regions, PFC, and hippocampus. Impaired activation of dorsal stream visual regions contributed significantly to impaired PFC activation, which contributed significantly to impaired activation of the hippocampus and ventral visual stream. Impaired ventral stream and hippocampal activation contributed significantly to deficits on neuropsychological measures of perceptual organization.
Schizophrenia is associated with severe activation deficits across a distributed network of sensory and higher order cognitive regions. Deficit in early visual processing within the dorsal visual stream contributes significantly to impaired frontal activation, which, in turn, leads to dysregulation of the hippocampus and ventral visual stream. Dysfunction within this network underlies deficits in more traditional neurocognitive measures, supporting distributed models of brain dysfunction in schizophrenia.