Input-output relations of the thalamic nonspecific system.

Abstract

A number of variants of the Golgi method have been used to examine neuropil patterns and input-output arrangements of the nonspecific (intralaminar) thalamic complex in adult cats. In comparison with previously used newborn material, it is clear that maturation brings with it considerable change in dendritic and axonal circuitry in both specific and nonspecific systems. The latter provides an extensive second projection system to cerebral cortex in parallel with specific sensory channels. In addition, its connections enable it to exert powerful modulatory forces on the entire dorsal thalamus. It is suggested that the caudally directed axonal path from nucleus reticularis thalami, in conjunction with the midline system, tune and shape those rhythmic slow wave processes which characterize thalamo-cortical operations.