Visceral Afferent Pathways and Central Projections

Abstract

As indicated above, there is no evidence in the literature that the formation of visceral receptor potentials and propagated action potentials differs from exteroceptive electrical events. Nevertheless, visceral afferent structures display a higher sensitivity to pharmacologically active substances and different chemicals than somatic sensory endings (Paintal, 1986). A number of other significant—mostly morphological—features distinguish the primary afferent visceral neuron from the somatic one, the first of which is the location of cell bodies within the afferent spinal and cerebral ganglia. These cell bodies are not randomly distributed, but rather form marked clusters. In spinal ganglia, these groupings of somata are located peripherally around fiber bundles, whereas in the nodose ganglion of the vagus the fiber packets surround the cell groups.