title: P300 subcomponents in obsessive-compulsive disorder.
abstract: Hyperactivity in the frontal cortex, leading to acceleration of attentional and cognitive processes, is discussed as pathogenetic factor in obsessive-compulsive disorder (OCD), as supported by findings of neuroimaging studies. This dysfunction in patients with OCD could be reflected by the auditory event-related P300 component, since one subcomponent of the P300, the so-called P3a, is mainly generated in frontal regions. The P300 of 21 patients with OCD free of medication and 21 age- and sex-matched healthy controls was studied, and dipole source analysis was used, allowing the separation of the subcomponents P3a and P3b with high reliability. No difference concerning the P3a between OCD and healthy subjects was found. OCD patients, however, showed a larger P3b amplitude and a shorter P3b latency (only right hemisphere) as well as a shorter reaction time to target tones as the healthy controls. Since the P3b, generated mainly in the temporo-parietal junction, is related to attentional and higher cognitive functions, whereas the P3a is more related to unspecific orienting reactions, the P3b abnormalities found in these patients could be an electrophysiological correlate of overfocussed attention and faster cognitive processes in OCD, possibly due to higher arousal and noradrenergic function. Regarding the findings with small P300 amplitudes and long latencies in most of the other psychiatric patients, it is remarkable that OCD is one of the few psychiatric diseases being characterized by larger P3b amplitudes and shorter latencies.
authors.affiliation: Department of Psychiatry, Section of Clinical Neurophysiology and Outpatient Clinic for Obsessive-Compulsive Disorder, Ludwig-Maximilians University Munich, Germany.
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Mavrogiorgou
authors.forename: Georg
authors.initials: G
authors.lastname: Juckel
authors.forename: Thomas
authors.initials: T
authors.lastname: Frodl
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gallinat
authors.forename: Walter
authors.initials: W
authors.lastname: Hauke
authors.forename: Michael
authors.initials: M
authors.lastname: Zaudig
authors.forename: Gerhard
authors.initials: G
authors.lastname: Dammann
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Möller
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hegerl
mesh_terms: D000328:Adult; D001479:Basal Ganglia / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D009771:Obsessive-Compulsive Disorder / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D011930:Reaction Time; D013702:Temporal Lobe / Q000503:physiopathology