MICROELECTRODE RECORDINGS FROM THE REGION OF THE NUCLEUS SOLITARIUS IN THE CAT

Abstract
An extracellular microelectrode exploration of the region of the nucleus solitarius has been carried out in 30 adult cats with the purpose of studying central projections of cardiovascular afferent fibers. Of 375 discharging cells encountered, only 9 showed a cardiac periodicity which was not obviously artefactual. The latter cells were located in the region of, or ventral to, the caudal part of the nucleus solitarius. The infrequency with which such cardiovascular patterns of discharge were encountered leads to the conclusion that primary cardiovascular afferents do not provide the dominant influence on discharge of secondary neurones of the nucleus solitarius. It is suggested that interruption of other sources of afferent input to these cells might reveal the nature of transfer of baroreceptor discharge pattern across the first synapse of the visceral afferent pathways for cardiovascular receptors.