Our collaboration with Katy Thakkar and her colleagues at Utrecht University has just assumed tangible shape. Our manuscript “Failure to use corollary discharge to remap visual target locations is associated with psychotic symptom severity in schizophrenia” has been accepted for publication in the Journal of Neurophysiology (which is becoming my favorite journal). In our study, we compared performance of schizophrenia patients and healthy controls in a perceptual localization task. The task required comparing the position of a small dot before a saccade to the position of a new dot after the saccade. This perceptual comparison requires that the system takes into account the size of the saccade—using a corollary discharge signal (i.e., an efference copy of the motor command)—in a process called remapping.
We show that the severity of psychotic symptoms predicts the failure of remapping in this task, at least to some degree. This finding supports the idea that psychotic symptoms are related to disturbed efference copy signals, which might give rise to the lack of agency that these patients experience.
You can find a pdf of the manuscript here.