The expansion of our understanding and knowledge of the mechanisms for the central neural regulation of organ functions is the long term objective of this proposal. Two brainstem nuclei, the dorsal motor nucleus of the vagus (DMX) and the nucleus of the tractus solitarius (NTS) have a unique role in autonomic regulation of organ function since these nuclei act as intermediaries between the central and peripheral nervous systems. In this proposal, the central autonomic neural connections of the dorsal motor nucleus of the vagus and the nucleus of the tractus solitarius will be investigated in relation to known peripheral connections to specific organs. The pigeon (Columba livia) provides an excellent model for this proposed study since organ-specific afferent and efferent peripheral connections are confined to specific subnuclei of NTS and DMX, respectively. The highly differentiated cytoarchitectonic subnuclear organization of NTS and DMX in the pigeon may correspond not only to a differential distribution of visceral connections but also to a segregation of central neural connections. Thus, one could speculate that central nuclei of the brain may modulate organ-specific functions via preferential central connections to specific NTS-DMX subnuclei. The correlation of a particular central neural cell group with a unique functional and anatomical subset of NTS-DMX neurons could provide a powerful model for future physiological and pharmacological investigations of central regulation of specific visceral functions.
The specific aims of this proposed study fall into two categories. 1A) The central afferent connections to NTS and DMX will be identified by the use of retrograde transport techniques. 1B) Subsequently, the central innervation of specific NTS-DMX subnuclei will be determined by anterograde fiber tracing methods. 1C) The central neural afferents to specific NTS-DMX subnuclei will be correlated with known peripheral connections to specific viscera. 2A) The efferent projections of NTS neurons to central neural cell groups will be investigated by the use of anterograde fiber tracing methods. 2B) Subsequently, the topographic organization of NTS cell bodies of origin of these fiber projections will be determined by retrograde tracing methods. 2C) These NTS cell bodies of origin of these central projections will be correlated with known peripheral sensory connections of specific organs to particular NTS subnuclei.
| Berk, M L (1991) Distribution and hypothalamic projection of tyrosine-hydroxylase containing neurons of the nucleus of the solitary tract in the pigeon. J Comp Neurol 312:391-403 |
| Berk, M L (1987) Projections of the lateral hypothalamus and bed nucleus of the stria terminalis to the dorsal vagal complex in the pigeon. J Comp Neurol 260:140-56 |
