Chapter 16 - Thalamus

Abstract

The present chapter describes the anatomical organization of nuclei of the thalamus, together with functions considerations. The chapter first discusses some general aspects of thalamic organization including functional subdivisions of the thalamus, the categorization of thalamic afferents as drivers or modulators, and reciprocity in thalamocortical relationships. The chapter then proceeds to individually discuss each of the major nuclei of the thalamus. This includes a description of their cellular properties and relative locations, their afferent and efferent connections, and their functions. The order of presentation is as follows: the lateral geniculate nucleus, the ventral posterior complex, the medial geniculate nucleus, the ventral anterior and ventral lateral nuclei, the ventral medial nucleus, the mediodorsal nucleus, the submedial nucleus, the anterior nuclei, the lateral nuclei, the intralaminar nuclei, the midline nuclei, and the reticular nucleus of thalamus. By comparison with previous chapters on the thalamus in this volume, greater emphasis is placed on the mediodorsal nucleus, the anterior nuclei, and the midline and intralaminar nuclei as main components of the “limbic thalamus,” and recently the subject of intense investigation from both an anatomical and functional perspective. The chapter attempts to dispel the notion that the thalamus is a (mere) relay for the transfer of sensorimotor information to the cortex but rather the thalamus is a vital hub in cortico-cortical and cortico-subcortical communication participating as a full partner in the range of functions generally strictly associated with the cortex.