Cerebral Cortex Advance Access published online on November 13, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp243
Diminished Parietal Cortex Activity Associated with Poor Motion Direction Discrimination Performance in Schizophrenia
1 Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115, USA, 2 College of Medicine, University of Kentucky, Lexington, KY 40506, USA, 3 Department of Psychology, 4 Department of Neuroscience, University of California, San Diego, CA 92093, USA, 5 Department of Psychology, 6 Department of Neuroscience, University of Georgia, Athens, GA 30602, USA, 7 BioImaging Research Center, University of Georgia, Athens, GA 30602, USA
Address correspondence to Brett Clementz, Psychology Department, Psychology Building, Baldwin Street, University of Georgia, Athens, GA 30602, USA. Email: clementz{at}uga.edu.
The results of multiple investigations indicate visual motion–processing abnormalities in schizophrenia. There is little information, however, about the time course and neural correlates of motion-processing abnormalities among these subjects. For the present study, 13 schizophrenia and 13 healthy subjects performed a simple motion direction discrimination task with peripherally presented moving grating stimuli (5 or 10 deg/s). Dense-array electroencephalography data were collected simultaneously. The goal was to discern whether neural deviations associated with motion-processing abnormalities among schizophrenia patients occur early or late in the visual-processing stream. Schizophrenia patients were worse at judging the direction of motion gratings, had enhanced early neural activity (about 90 ms after stimulus onset), and deficient target detection–related late neural activity over parietal cortex (about 400 ms after stimulus onset). In addition, there was a strong association (accounting for 36% of performance variance) between poor behavioral performance and lower target detection–related brain activity among schizophrenia patients. These findings suggest that abnormalities in later stages of motion-processing mechanisms, perhaps beyond extrastriate cortex, may account for behavioral deviations among schizophrenia subjects.
Key Words: ERP • motion • motion processing • P1 • parietal cortex • schizophrenia • smooth pursuit • visual