[Thalamocortical relationships during spontaneous and evoked rhythmic activity of the brain]

A study was made in lightly nembutalized and unanaesthetized immunobilized cats of the interrelations between rhythmic afterdischarge evoked in the auditory cortex by a click, and a spontaneous spindle burst under different states of intact animals. The experiments showed: 1) Rhythmic afterdischarge represents a stimulus induced spindle burst, 2) local spindle burst (spontaneous or evoked by peripheral and central stimulations) in the auditory cortex does not change considerably either by stimulation or by lesion of thalamic nonspecific, as well as other specific structures; 3) An afterdischarge in the medial geniculate body (evoked by a click) remains unchanged after cooling or extirpation of the whole auditory cortex. All this suggests a generation of both spontaneous and evoked local rhythmic activity of the auditory thalamo-cortical system, independent of other such systems.