Somatotopic organization of mechanoreceptor units in the trigeminal nuclear complex of the macaque

Abstract

Abstract The properties of neurons in the sensory trigeminal nuclear complex of macaque monkeys have been investigated by a systematic exploration of the principal sub‐divisions in an attempt to define somatotopic organization, modality representation, receptive field size and adaptive properties. Particular attention was paid to several discrepancies in the literature on the cat trigeminal complex. The results suggest that each cutaneous locus is represented by a rostro‐caudally oriented column of neurons possessing comparable properties and receptive field sizes at all levels examined in deeply anesthetized animals. A consistent somatotopic pattern with minor variations, was evident at all rostro‐caudal levels. Criteria for distinguishing “spinothalmic” and “lemniscal” neuron properties in appropriate portions of the sensory complex (inferred from human data) could not be identified. Neurons in adjacent structures may respond to crude stimuli and lack distinct receptive fields, but it is unlikely that these are related to an afferent “pain” pathway.