Brain Advance Access published online on August 19, 2008
Brain, doi:10.1093/brain/awn184
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Correlation of passivity symptoms and dysfunctional visuomotor action monitoring in psychosis
1Department of Psychiatry and Psychotherapy, Division of Medical Psychology, University Hospital of Bonn, 2Department of Psychiatry and Psychotherapy, University Hospital of Cologne, Germany, 3Psychiatric University Hospital, Zürich, Switzerland, 4Interdisciplinary Center for Clinical Research (ICCR), Functional Neuroimaging Unit, RWTH Aachen and 5Department of Radiology, University Hospital of Cologne, Germany
Correspondence to:
Dr Knut Schnell, Abteilung für Medizinische Psychologie, Zentrum für Nervenheilkunde, Universitätsklinikum Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany E-mail: knut.schnell{at}ukb.uni-bonn.de
Passivity experiences are hallmark symptoms of schizophrenia that can be characterized by the belief that one's thoughts or actions are controlled by an external agent. It has recently been suggested that these psychotic experiences result from defective monitoring of one's own actions, i.e. disturbed comparison of actions and perceived outcomes. In this study, we examined the function of the previously characterized action monitoring network of the inferior parietal lobule (IPL), medial (mPFC) and lateral prefrontal cortices in patients with different levels of passivity symptoms with an fMRI task. The visuomotor fMRI task demanded control of visually perceived object movements by alternating button presses with the left and the right index finger. In the monitoring condition of this task subjects stopped their actions whenever they detected visuomotor incongruence. fMRI and behavioural data from 15 patients were tested for correlation with passivity symptoms using standardized Scale for Assessment of Positive Symptoms (SAPS)- and AMDP- passivity symptom ratings. Both types of data were tested for differences between the patients group and 15 healthy controls. In the patient group we found the expected correlation of passivity symptoms and visuomotor monitoring performance. There was a significant positive correlation of passivity symptoms with increased latency of incongruence detection and a negative correlation of SAPS-passivity with the number of detected events. fMRI data revealed correlations of passivity symptoms with activation in bilateral IPL, primary motor and sensory cortices in the action monitoring condition. A correlation of passivity symptoms with the main experimental effect (actions with – actions without monitoring) was found in the posterior cingulate cortex (PCC) and in the left IPL. No group differences or group by task interactions were found within the visuomotor-action-monitoring network. Our results demonstrate the association between passivity symptoms and the dysfunction of visuomotor action monitoring and support the idea that psychotic passivity experiences result from dysfunctions of central action monitoring mechanisms: According to pre-existing concepts of parietal cortex function, IPL-hyperactivation may represent an increase in false detections of visuomotor incongruence while the correlation between passivity and the differential effect of monitoring on PCC-activation assumedly represents greater self-monitoring effort in passivity experiences.
Key Words: action monitoring; visuomotor; schizophrenia; functional magnetic resonance imaging; parietal lobe
Abbreviations: AIMS, Abnormal Involuntary Movement Scale; BA, Brodmann area; CC, control condition; EPI, echoplanar imaging; EPS, Extrapyramidal Motor Side Effects Scale; FDR, false discovery rate; HRF, hemodynamic response function; IPL, inferior parietal lobule; MC, monitoring condition; mPFC, medial prefrontal cortex; PCC, posterior cingulate cortex; SANS, Scale for Assessment of Negative Symptoms; SAPS, Scale for Assessment of Positive Symptoms; SCID, Structured Clinical Interview for DSM-IV Axis I Disorders; SPM, Statistical Parametric Mapping
Received February 25, 2008. Revised July 7, 2008. Accepted July 21, 2008.