Neurons of the nucleus tractus solitarius, in vitro, generate bursting activities by solitary tract stimulation.

Extracellular recordings of the activity of nucleus tractus solitarius (NTS) neurons were performed on rat brainstem slice preparations. Neurons localized in the medial part of the lateral NTS, which displayed a synaptic response to single pulse stimulation of the tractus solitarius (TS), generated bursting activity following repetitive TS stimulation (20-50 Hz frequency, 100-600 ms duration). According to their patterns of discharge and to the duration and frequency of their bursting activities, these neurons were classified in three groups called type A, B and C. We suggest that different cellular intrinsic properties, rather than local synaptic interactions, might be involved in the generation of these three types of bursting activities. These results are discussed in terms of the role of NTS neurons in the generation of the swallowing motor pattern.