Electrophysiological and morphological characteristics of nucleus tractus solitarii neurons projecting to the ventrolateral medulla.

Electrophysiological and morphological properties of a direct projection from the nucleus of the tractus solitarius (NTS) to the ventrolateral medulla (VLM) were investigated. NTS neurons projecting to the VLM exhibit a monosynaptic excitatory response followed by an inhibitory one after the tractus solitarius stimulation. These neurons show spontaneous inhibitory postsynaptic currents, and have medium to large soma (14-26 microm in diameter). It is concluded that the projection from the NTS to the VLM is mediated mostly by medium to large neurons that are inhibited locally by GABAergic interneurons within the NTS.