[The novelty factor and asymmetry in brain activity]

Abstract

In case of repeated presentation of monotonous tasks or stimuli, based upon EP and EEG parameters, the zone of increased activation in human cortex in which the shortest EP latent period, the highest alpha-rhythm frequency were recorded did not remain stable but as the stimulation continued, shifted from the frontal region of the left hemisphere to the occipital region of the right hemisphere. It was shown in dogs that introduction of combination of the conditioned stimulus with food reinforcement resulted in an increase in the number of cases with maximal values of EEG frequency in the left hemisphere. In cats during orienting reaction to clicks, correlation between averaged EPs of the auditory cortex, amygdala and hypothalamus was dominant in the left hemisphere. After extinction of the orienting reaction, the correlation shifted to the right hemisphere. A conclusion was drawn on the universality of activation of the structures mainly of the left hemisphere as a reaction to novelty in man and animals. It made the role of the left and right frontal neocortex in emergence of positive or negative emotions more clear.