Disrupted Saccadic Corollary Discharge in Schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Science

Background:

• Schizophrenia is a debilitating mental disorder characterized by a loss of agency.
• Alterations in corollary discharge (CD), which predicts sensory consequences of self-generated actions, are hypothesized to underlie these symptoms.
• Previous research in primates linked CD dysfunction to medial thalamus activity.

Purpose of the Study:

• To investigate corollary discharge (CD) function in schizophrenia patients using a modified saccadic double-step task.
• To provide direct human evidence for CD disruptions in schizophrenia and link it to neurophysiology.

Main Methods:

• Human participants (schizophrenia patients and healthy controls) performed a modified double-step eye-movement task.
• Researchers analyzed corrective saccades following erroneous eye movements to assess CD.
• Key metrics included corrective saccade frequency, latency, and mislocalization.

Main Results:

• Schizophrenia patients exhibited fewer and slower corrective saccades compared to controls.
• The corrective saccades in patients were mislocalized in a direction consistent with disrupted CD.
• These findings provide clear evidence for dysfunctional CD in the oculomotor system of schizophrenia patients.

Conclusions:

• The study demonstrates impaired corollary discharge (CD) in schizophrenia patients during an eye-movement task.
• Findings support the theory that CD disruptions contribute to the loss of agency in schizophrenia.
• The results suggest that medial thalamus dysfunction may be the neurophysiological basis for these CD impairments.