Biomedical subjects
G Stolz
Publications and source records attributed to G Stolz.
Prolonged latencies of the N2 and P3 of the auditory event-related potential in children at risk for schizophrenia. A preliminary report.
In previous studies investigating long latency components of the event-related potential (ERP), schizophrenic patients generally showed reduced P3 amplitudes and in some studies prolonged N2 or P3 latencies. As there is a higher risk of offspring of schizophrenics than of mentally healthy parents developing this disease, the present study was intended to clarify whether ERP components (in particular the N2 and P3) differ between these two groups of children. Twelve high-risk and 12 age-matched control children (aged 9-16 years) performed an auditory oddball task in order to assess late ERP components. This task required the subject to covertly count rare target tone pips (P = 0.2) irregularly interspersed among frequent standard tone pips (P = 0.8) in two series of 400 pips. ERPs were recorded from midline electrodes (Fz, Cz, Pz). The results indicated distinctly prolonged N2 and P3 latencies in ERPs to target stimuli in children of schizophrenic patients. These findings suggest a slowed target classification in these children.
VEP, physiological and psychological circadian variations in humans.
Amplitudes and latencies of components of visual evoked potentials (VEPs) were analysed during the 24-h cycle in humans. Circadian variations of other physiological parameters (oral temperature, urine volume and urinary potassium excretion) and of psychomotor performance (grip strength, tapping rate, visual reaction time and performance on a letter cancellation test) were also assessed. Eight male volunteers (aged 20-34 years) were tested twice over a period of 30 h. Test sessions took place every 3 h (1100 hours, 1400 hours etc.). VEPs were elicited by checkerboard pattern reversals. Significant circadian variations in the VEPs were found for the latencies of the P100 and N140 components, which were longest between 2 a.m. and 5 a.m. (P100: 103 ms; N140: 138 ms) and shortest at about 5 p.m. (P100: 97 ms; N140: 130 ms). Pronounced circadian variations were also observed in physiological parameters and in psychomotor performance measures. Circadian variation of oral temperature was correlated with the 24-h profiles of most of the other variables. Time courses of VEP latencies and oral temperature were moderately negatively correlated. However, from the data presented it seems premature to conclude that there is a common pacemaker for the circadian variations of the different parameters investigated.
Circadian variation in the visual evoked potential (VEP).
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