General Organization and Parallel Pathways in the Somatosensory System

Abstract

Abstract The processing of somatosensory stimuli from periphery to cortex occurs along ascending neural channels, segregated by their stimulus features and locations throughout the head and body. This chapter describes the 2 main parallel pathways in humans and discusses further details at the level of thalamus and cortex using animal models. Research using animal models has focused on the body part specialized for each species, which limits generalizations to mammalian somatosensory processing. Primate work has focused on neural recordings in the monkey using hand stimuli, while understanding the organization in rodents has generally been investigated in the whisker system. In both species, integration of the pathways occurs in primary somatosensory cortex and up the cortical hierarchy, despite anatomically parallel inputs to cortex. Anatomical tracing across multiple synapses, combined with detailed functional classification of the projections, will be key to understanding the processing of such diverse sensory inputs.