Afferent projections to the lateral cervical nucleus: a microelectrode study

Abstract

The lateral cervical nucleus was explored with microelectrodes in lightly anesthetized cats. Extracellular responses were recorded from 160 neurons following physiological stimulation of the ipsilateral side of the body from the neck to the tail. The stimuli activating the neurons were touch, pressure, and joint movement. Neurons responding to touch were more prevalent than neurons responding to pressure on the skin or on deep structures; those responding to joint movements were a small fraction of the neuronal sample studied. For the three stimuli tested, the limbs were more prominently represented than the trunk. Tactile and pressure peripheral fields activating single neurons were of three types: restricted (a few hairs, small areas within one segment of a limb), large (wide areas of the trunk, whole limb), and very large (whole ipsilateral aspect of the body, both limbs). Restricted fields were less numerous than the large fields. One-third of the fields activating single neurons following tactile stimulation was of the very large type. The existence of the very large fields indicated a high degree of convergence of afferents onto neurons of the cervical nucleus.