Electrophysiological properties of units of the thalamic reticular complex

Abstract

Unit activity was recorded in and close to the thalamic reticular complex in encéphale isolé cats. A group of units was characterized by their long high-frequency burst responses to 10/sec thalamic and cortical stimulations, their sustained high-frequency firing induced by 40–250/sec thalamic and cortical stimulations, the depression of their firing by high-frequency stimulations of the midbrain reticular formation and caudate nucleus, and their tendency to be more active during EEG spindles. These units were located along tracks histologically found crossing the thalamic reticular complex. They differed from cells collected along tracks not crossing the reticular complex, on all four electro-physiological properties mentioned above. These properties are shown to be intrinsic for a class of neurons, presumably of the reticular complex. The timing of firing of reticularis and nonreticularis neurons is compared and it is suggested that reticularis neurons are at the origin of inhibition of dorsal thalamic cells. It is also postulated that they play a role in the control of thalamic spindle waves.