Diminished parietal cortex activity associated with poor motion direction discrimination performance in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Visual Perception

Background:

• Visual motion-processing abnormalities are noted in schizophrenia.
• The temporal dynamics and neural underpinnings of these deficits remain unclear.

Purpose of the Study:

• To investigate the time course and neural correlates of visual motion-processing deficits in schizophrenia.
• To determine if abnormalities occur early or late in the visual processing stream.

Main Methods:

• 13 schizophrenia patients and 13 healthy controls performed a peripheral motion direction discrimination task.
• Dense-array electroencephalography (EEG) recorded neural activity.
• Stimuli included moving gratings at 5 or 10 deg/s.

Main Results:

• Schizophrenia patients exhibited poorer motion direction judgment.
• Enhanced early neural activity (approx. 90 ms) and deficient late neural activity (approx. 400 ms) over parietal cortex were observed.
• Poor performance strongly correlated with reduced late neural activity (36% variance).

Conclusions:

• Schizophrenia is associated with abnormal visual motion processing.
• Deficits appear linked to abnormalities in later visual processing stages, potentially beyond extrastriate cortex.
• These later-stage abnormalities may explain behavioral impairments in schizophrenia.