Morphological and functional diversity of first-order somatosensory neurons
First-order somatosensory neurons transduce and convey information about the external or internal environment of the body to the central nervous system. They are pseudo unipolar neurons with cell bodies residing in one of several ganglia located near the central nervous system, with the short branch of the axon connecting to the spinal cord or the brain stem and the long branch extending towards the peripheral organ they innervate. Besides their sensory transducer and conductive role, somatosensory neurons also have trophic functions in the tissue they innervate and participate in local reflexes in the periphery. The cell bodies of these neurons are remarkably diverse in terms of size, molecular constitution, and electrophysiological properties. These parameters have provided criteria for classification that have proved useful to establish and study their functions. In this review, we discuss ways to measure and classify populations of neurons based on their size and action potential firing pattern. We also discuss attempts to relate the different populations to specific sensory modalities.
KeywordsSomatosensory neurons Phasic neurons Tonic neurons Neuronal size Firing pattern
Supported by the Brazilian institutions: Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG).
Compliance with ethical standards
Conflict of interest
Eder Ricardo de Moraes declares that he has no conflicts of interest. Christopher Kushmerick declares that he has no conflicts of interest. Lígia Araujo Naves declares that she has no conflicts of interest.
This article does not contain any unpublished studies with human participants or animals performed by any of the authors.
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