title: Influence of reference electrodes, stimulation characteristics and task paradigms on auditory P50.
abstract: To clarify the nature of auditory P50, middle latency auditory evoked potentials were recorded by using different conditions of reference electrodes (linked earlobes, LE; balanced non-cephalic, BN), stimulation characteristics (tone burst, human voice) and tasks (counting, simple reaction) in 10 right-handed males (aged 21-36 years). EEG was recorded from Fz, Cz, Pz, C3, C4, T3 and T4 according to the 10-20 system. Two groups of electrode sites were made for the statistical analysis: a midline group, Fz, Cz and Pz, and a lateral group, T3, C3, Cz, C4 and T4. The results were that the P50 amplitudes with BN electrodes were significantly higher than those with LE in both groups (midline, P < 0.01; lateral, P < 0.01); the P50 amplitudes by voice stimulation were significantly higher than those by tone stimulation in the lateral group (P < 0.05), and the P50 latencies under a simple reaction paradigm were significantly shorter than those under a counting task in both groups (midline, P < 0.05; lateral, P < 0.05). These results suggest that various factors including motor response affect the P50 amplitudes and latencies.
authors.affiliation: Department of Neuropsychiatry, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: H
authors.initials: H
authors.lastname: Ninomiya
authors.forename: T
authors.initials: T
authors.lastname: Onitsuka
mesh_terms: D000161:Acoustic Stimulation / Q000295:instrumentation; D000328:Adult; D004566:Electrodes; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D008297:Male; D009043:Motor Activity; D013647:Task Performance and Analysis