THE DORSAL NUCLEUS OF THE LATERAL LEMNISCUS IN THE MOUSTACHE BAT - MONAURAL PROPERTIES

Neurons in the mustache bat dorsal nucleus of the lateral lemniscus (D NLL) were examined in response to monaural stimulation. There are six main findings of this study. First, the mustache bat DNLL is tonotopic ally organized. Second, EI cells are the predominant aural type and co mprise about 80% of DNLL neurons, whereas monaural and EE cells are fa r less numerous. Third, the majority of DNLL neurons have either monot onic or weakly nonmonotonic rate-intensity functions. Fourth, a choppi ng pattern is evoked by contralateral stimulation in 58% of DNLL neuro ns and is the predominant temporal response pattern. Fifth, neurons wi th different aural properties tend to exhibit different temporal respo nse patterns: EI cells are largely choppers, while EO and EE cells are more often primarylike or primarylike-with-notch. Sixth, the sustaine d responses of EE units to contralateral stimulation differs dramatica lly from their onset responses to ipsilateral stimulation. Here we hav e demonstrated that although a large proportion of mustache bat DNLL n eurons are EI choppers, the DNLL nonetheless contains a heterogeneous population of neurons based on physiological responses to pure tones.