Effects of stimulation intensity, gender and handedness upon auditory evoked potentials.

Left handers and women show less anatomical brain asymmetry, larger corpus callosum and more bilateral representation of specific functions. Sensory and cognitive components of cortical auditory evoked potentials (AEP) have been shown to be asymmetric in right handed males and to be influenced by stimulus intensity. In this study the influence of sex, handedness and stimulus intensity upon AEP components is investigated under basal conditions of passive attention. 14 right handed males, 14 right handed females, 14 left handed males, and 14 left handed females were studied while lying awake and paying passive attention to auditory stimulation (series of 100 binaural clicks, duration 1 msec, rate 1/sec, at four intensities). Cz, C3 and C4 referenced to linked mastoids and right EOG were recorded. Analysis time was 400 msec, average evoked potentials were based on 100 clicks. Stimulus intensity and gender affect early sensory components (P1N1 and N1P2) at central leads, asymmetry is influenced only by handedness, right handers showing larger P1N1 amplitudes over the right hemisphere.