Neurons in the inferior colliculus of the mustached bat are tuned both to echo-delay and sound duration.

Echolocation in bats requires a precise temporal processing of complex signals. This processing of time includes the encoding of echo-delay, which gives an estimation of target distance, and sound duration, which is considered to be important for own sound or echo recognition. In this study, we report that delay-tuned neurons in the inferior colliculus of the mustached bat (Pteronotus parnellii) are also tuned to sound duration. Collicular delay-tuned neurons showed three types of duration tuning: short-pass (12 of 64), band-pass (16 of 64), and long-pass (17 of 64). The remaining 19 delay-tuned neurons are not selective for sound duration. All short-pass and 10 band-pass neurons' characteristic delays were similar to characteristic duration. In six band-pass neurons, characteristic delay was different from characteristic duration. Neurons processing unmatched delay and durations could be participating in complex kinds of processing where the same neuron has different functions depending on the activated neural network.