Processing of afferent inputs in cardiovascular control.

The present report describes the use of an antidromic mapping technique to define the extent and localisation of the afferent projections of the arterial baroreceptors and chemoreceptors to the medulla oblongata. There are distinct differences in their pattern of projection: baroreceptors project primarily laterally, chemoreceptors medially, to regions which are also innervated by lung stretch afferents. Baroreceptors, however, do project to medial regions of the nucleus tractus solitarius and the significance of these patterns of projection is discussed in relation to the respiratory modifications of the performance of the baroreceptor reflex. The diencephalic control of transmission of the baroreceptor reflex is also discussed in the light of the marked innervation that the nucleus tractus solitarius receives from cell groups in the diencephalon.