健常男性成人と健常女性成人における大脳誘発電位の相違

Sex differences in SEP (Somatosensory Evoked Potential) and EEG were studied with 90 healthy adult males (mean age=25.3±3.1 y.o.) and 96 adult females (mean age=21.6±2.7 y. o.). SEPs evoked by median nerve stimuli were recorded with 1000 msec of analysis time through the two derivations (bipolar: C3’→F3’ and monopolar : C3’→A1+2). The differences between the two group mean SEPs of each sex were studied. The differences in latencies and interpeak amplitudes of individual SEPs between sexes were tested statistically. The following results were obtained. 1. In the waveform of group mean SEP, there were differencies between N 3 and P 6, with P 4 (bipolar), and P 5, N 5 (monopolar) for females but not for males. The latencies of most of components were shorter, and interpeak amplitudes were larger in females than in males. 2. In the individual SEP most of latencies were significantly shorter and interpeak amplitudes were significantly larger in females than in males. 3. The significant sex differences in latencies and amplitudes of SEP components were verified even after excluding the influences of age and stature, by analysis of covariance. 4. In EEG, θ, β 1 and β 2 power % were larger, and δ and α 2 power % were smaller in fem ales than in males. The sex differences in SEP verified in this study might be attributed to larger corpus callosum and less differentiated lateralities of the brain in females than in males, and the differences in sex hormon between the two sexes

Sex differences in Auditory Evoked Potential (AEP) and EEG of healthy adults

Sex differences in AEP (Auditory Evoked Potential) and EEG were studied with 100 healthy adult males (mean age=25.4± 3.1 y. o.) and 100 adult females (mean age=21.6± 2.6 y. o.). AEPs evoked by binaural clicks were recorded with 1024 msec of analysis time through the two derivations (3CH : Cz→A1+2 and 6CH : Cz→T5). The differences between the two group mean AEPs of each sex were studied. The differences in latencies and peak-to-peak amplitudes of individual AEPs between sexes were tested statistically. The following results were obtained. 1 The waveform of group mean AEPs of each sex had hexaphasic contour, consisted of components P1~N8, including the prominent negative peak N4 and positive peak P5, within 600 msec of latency. 2 The contours of group mean AEP were similar in both sexes, but the latencies of the components were shorter, and peak-to-peak amplitudes were larger in females than in males. 3 Most of latencies and peak-to-peak amplitudes were significantly shorter in females than in males by t-test. 4 The significant sex differences of latencies and amplitudes of AEP components, including the most prominent component P5, were verified even after excluding the influence of stature and body weight, by analysis of covariance. 5 Quantitative analysis of EEG between sexes resulted in larger band amplitude in males and significantly larger θ and β1 power % and smaller α2 power % in females. The sex differences in AEP verified in this study were attributed to the less differentiated lateralities of the brain in females, than in males