Spontaneous electrical activity of the claustrum

Abstract

The dynamics of spontaneous electrical activity of the rostral, dorsal, ventral, and caudal parts of the claustrum were studied in chronic experiments on 12 dogs with implanted electrodes during extinction of orienting reactions and during biologically meaningful changes in the animals' functional state. In the animal at rest, electrical activity of the claustrum was similar to that of subcortical structures, but in a state of attention, its activity began to resemble that of the electrocorticogram, in agreement with the view that this nucleus occupies an intermediate position between cortical and subcortical structures. Enhancement of fast activity in the claustrum with the appearance of orienting reactions was expressed more intensively, and during extinction it was preserved for a longer time, in the dorsal and ventral parts of the claustrum than in the rostral and caudal parts, evidence of structural heterogeneity of the nucleus. Under conditions of increased food excitability the amplitude and frequency of the fast waves recorded from the rostral and caudal parts of the claustrum were selectively increased, whereas during reflexes to a rejected stimulus (acids) and in defensive reflexes they were increased in recordings from the dorsal and ventral parts, on which basis the existence of specialized efferent zones participating in biologically different types of activity can be postulated. Enhancement of fast activity in the claustrum during reflexes to food and acid differed in its genesis: The switch from the first to the second took place through a phase of suppression of the first. Differentiation of a food-conditioned stimulus was accompanied by the development of active inhibition in the "food zones" of the claustrum and by enhancement of activity in the "zones of orienting reactions."