Genetic effects in the cortical auditory evoked potential: a twin study.

An experiment was carried out on 40 pairs of adult male twins to investigate the extent of genetical determination in the cortical auditory evoked potential. Tonal stimuli of 1 sec duration, at an intensity of 95 dB and a frequency of 100 c/sec, were used. The inter-stimulus interval was 33 sec and the bipolar evoked potential was measured between the CZ and T3 scalp positions. The reliability of the seven latency and amplitude measures was also calculated and this was taken into account in the subsequent genetic analysis. The biometrical gentical approach, which gives maximal information particularly on small samples, was used to analyse the data. A strong genetic influence was found on all the amplitude scores. The environment made no significant contribution to these. For the latencies there was some evidence for a genetic effect; however, this was not very strong and can well be interpreted as being due to between family environmental effects.