Action control in patients with schizophrenia or obsessive-compulsive disorder

The present project investigates putative impairments of volitional action in patients with schizophrenia (SZ) or obsessive-compulsive disorder (OCD). Previous studies revealed that the latencies of volitional but not visually-guided saccades are increased in SZ patients compared to healthy control (HC) subjects. In line with major theories of schizophrenia, these findings may indicate a deficit of the volitional initiation of action. In order to validate this assumption, the first project part intended to replicate previous findings, to probe the role of endogenous attention shifting, and to evaluate electrophysiological indices of impaired initiation of manual movements. In addition, we picked up preliminary evidence of a similar deficit in OCD patients and tested specific hypotheses on volitional saccade generation in this population. Three studies showed that 1.) volitional saccade have increased latencies in OCD patients, 2.) an increased latency of the lateralized readiness potential (LRP) reflects slowed initiation of manual responses in SZ patients, and 3.) endogenous attention shifting and volitional saccade initiation are dissociable. However, we failed to replicate increased volitional saccade latencies in SZ patients. Thorough comparison with previous studies suggests that the offset of a central fixation stimulus, which served as imperative stimulus in the present study, may compensate the putative deficit of volitional saccade initiation. With a renewal proposal we intend to test this hypothesis by investigating the known fixation offset effect (FOE) in SZ patients, OCD patients, and HC subjects. Other new experiments refer to the hypothesis that the putative deficits in volitional saccade initiation are determined by an impaired ability to strategically adapt (oculomotor) action readiness. Finally, we propose to probe impaired volitional initiation of action in OCD patients by measuring LRPs in manual response tasks.

Principal Investigators
Reuter, Benedikt Dr. rer. nat. (Details) (Clinical Psychology)

DFG: Sachbeihilfe

Duration of Project
Start date: 11/2010
End date: 11/2012

Kloft, L., Reuter, B.; Riesel, A.; Kathmann, N. (2011). Impaired volitional saccade control: first evidence for a new endophenotype in obsessive-compulsive disorder. Manuscript submitted for publication.

Last updated on 2020-11-03 at 23:12