Instability of visual error processing for sensorimotor adaptation in schizophrenia.

Area of Science:

• Neuroscience
• Cognitive Psychology
• Psychiatry

Background:

• Saccadic adaptation is a valuable tool for studying sensory processing and motor learning.
• Investigating saccadic adaptation in schizophrenia offers insights into sensorimotor disturbances and cognitive deficits in the disorder.

Purpose of the Study:

• To determine if patients with schizophrenia can adjust saccadic amplitudes in response to visual errors during saccade execution.
• To assess the transfer of saccadic adaptation to a visuo-manual localization task in schizophrenia.
• To explore potential differences in adaptation speed and variability between patients and healthy controls.

Main Methods:

• Fourteen patients with schizophrenia and 14 healthy controls performed 200 saccadic adaptation trials with a 4° outward target shift.
• Eye movements were recorded at 1000 Hz to measure saccade amplitude changes and variability.
• Visuo-manual localization of a flashed stimulus post-saccade was used to assess transfer of adaptation.

Main Results:

• Saccade amplitudes increased by 11% in both groups, indicating similar adaptation strength.
• Patients exhibited higher amplitude variability and slower adaptation speeds compared to controls.
• The adaptation process similarly shifted visual space perception in both groups, suggesting unimpaired transfer.

Conclusions:

• The ability to use visual error signals for sensorimotor recalibration and its transfer to visual perception is largely intact in schizophrenia.
• Increased saccadic amplitude variability in patients may indicate instability in cerebellar systems.
• Slower adaptation speeds in schizophrenia could stem from reliance on frontal circuitry for visual error processing.