The dorsal nucleus of the lateral lemniscus in the mustache bat: monaural properties.

Neurons in the mustache bat dorsal nucleus of the lateral lemniscus (DNLL) were examined in response to monaural stimulation. There are six main findings of this study. First, the mustache bat DNLL is tonotopically organized. Second, EI cells are the predominant aural type and comprise about 80% of DNLL neurons, whereas monaural and EE cells are far less numerous. Third, the majority of DNLL neurons have either monotonic or weakly nonmonotonic rate-intensity functions. Fourth, a chopping pattern is evoked by contralateral stimulation in 58% of DNLL neurons and is the predominant temporal response pattern. Fifth, neurons with different aural properties tend to exhibit different temporal response patterns: EI cells are largely choppers, while EO and EE cells are more often primarylike or primarylike-with-notch. Sixth, the sustained responses of EE units to contralateral stimulation differs dramatically from their onset responses to ipsilateral stimulation. Here we have demonstrated that although a large proportion of mustache bat DNLL neurons are EI choppers, the DNLL nonetheless contains a heterogeneous population of neurons based on physiological responses to pure tones.