Concluding Remarks

Abstract

Walker in 1938 was able to end his book The Primate Thalamus with a lengthy chapter entitled “The Anatomical, Physiological and Clinical Significance of the Thalamus.” In this he concluded that the thalamus was composed of three fundamentally different groups of nuclei: midline and intralaminar nuclei projecting to other diencephalic structures; three relay nuclei (ventral posterior and the geniculate bodies); and a phylogenetically recent group including mediodorsal, lateral posterior, and pulvinar nuclei not receiving fibers from the principal afferent pathways. It was his viewpoint that these latter nuclei and the thalamus in general was an integrative center for all incoming stimuli, elaborating them before presentation “to the highest hierarchy of the central nervous system, the cerebral cortex, as complex and at least partially synthesized impulses.” His belief in the thalamus as a sensory integrative center seems to have derived from the clinical observation that lesions at upper levels of the neuraxis rarely lead to a disturbance of single sensory modalities. He recognized nevertheless that spatial relationships would be preserved through the thalamus because of the topographic ordering of inputs and of thalamocortical projections.

Even a fool can farm When he lights on fertile ground. Rich crops have no need Of merit in the sower.

VÍãkhadatta, Rakshasa’s Ring, translated by Michael Coulson