Personality trait of behavioral inhibition is associated with oscillatory systems reciprocal relationships.

The main aim of this paper is to offer a speculative evolutionary based interpretation of brain oscillations. We suppose that delta, theta and alpha oscillations are informational channels of three hierarchical philogenetic systems. Delta oscillations are linked with the most ancient system, which was dominant in reptilian brain. Theta oscillations dominate in lower mammals. Alpha oscillations are manifestation of activity of the newest system, which dominate in adult humans. The three hierarchical phylogenetic systems fulfill parallel processing and their contribution to resulting behavior could differ in different individuals. Relative contribution of each system is regulated by means of descending inhibition (DI), higher systems inhibiting the lower. One of this theory's implications is that the personality trait of behavioral inhibition (behavioral inhibition system, BIS) should be associated with a stronger DI but particular mechanism could be different in children and adults. In order to test this hypothesis in 95 children (11-16 years) and 45 adults (18-37 years) resting EEG recordings were obtained along with BIS scores assessed by the Gray-Wilson Personality Questionnaire. Within subject strength of DI was measured by negative correlations between delta, theta and alpha powers estimated in individually adjusted EEG bands. In adults, BIS was associated with enhanced negative feedback from the alpha to the delta system, indicating a predominantly cortical origin of the adult humans' anxiety. In children, BIS was associated with enhanced negative relation between theta and delta systems, which is similar to the mechanism known in animals where limbic system plays the crucial role in mediating anxiety and fear. Although the presented empirical data partly supported the theory, it remains to be speculative and needs further empirical validation.