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G Valerius

Publications and source records attributed to G Valerius.

4 recordsLinked to original sources
PubMed2004

Event-related potential correlates selectively reflect cognitive dysfunction in schizophrenics.

UNLABELLED: Schizophrenics show event-related potential (ERP) and particularly P3 abnormalities. To study the more detailed relationships between these ERP alterations and cognitive dysfunction we recorded and analyzed ERPs using a particular experimental approach. In 34 schizophrenics and 25 controls ERPs were obtained by a visual Go/Nogo task requiring response inhibition and were decomposed into temporally independent topographical components using Independent Component Analysis (ICA). ICA disentangled different subcomponents of P3. Subcomponent P3b with a parietal maximum amplitude was significantly reduced in the schizophrenics, probably reflecting their attentional deficits. Subcomponent P3ng with a frontal maximum amplitude and enhanced during Nogo condition appeared as an electrophysiological index of response inhibition. A significantly reduced P3ng enhancement, found in schizophrenics, probably reflects their impaired response control. CONCLUSIONS: ICA can successfully identify ERP subcomponents with distinct scalp topographies representing significant differential indices of normal and abnormal cognitive processing. Involvement of frontal brain areas in disturbed executive control in schizophrenics is supported by our ICA findings.

Adult↗
PubMed2003

Is the antidepressive effect of sleep deprivation stabilized by a three day phase advance of the sleep period? A pilot study.

Sleep deprivation (SD) induces a rapid amelioration of mood in about 60 % of depressed patients. After the next night of sleep, however, most patients experience a relapse. Previous studies demonstrated that a six day sleep-phase advance protocol prevents relapses in about 60 % of patients who responded positively to SD. We investigated whether also a three day phase advance of the sleep period might be able to maintain the antidepressant effects of SD. Twenty-eight medicated depressed inpatients, who had a significant improvement after a SD in one night were recruited for this study. The phase advance protocol began on the first day after SD with a bed time from 5:00 p. m. to 12:00 p. m. on the first, from 7:00 p. m. to 2:00 a. m. on the second and 9:00 p. m. to 4:00 a. m. on the third day after SD. Three patients dropped out because of protocol violations. Only ten of the remaining 25 SD responders had a relapse during the three days of phase advance treatment or during the two days after it. Two of the relapsers improved again until day 6, i. e. 68 % showed an improvement of at least 30 % six days after the beginning of the treatment. This study indicates that even a three day phase advance protocol may help to prevent relapses after successful SD.

Circadian Rhythm↗