Figure 1.

Sonar vocal behavior, audiovocal neuronal circuitry, dorsal SC position, and experimental subject. A, Time waveform and selected spectrograms of a sequence of sonar vocalizations produced by a flying bat attacking a stationary insect target. Typical of an insect pursuit sequence, there are dynamic changes in the sonar pulse intervals as bats approach and capture a target (top). The representative spectrograms demonstrate the change in bandwidth, call duration, and sweep rate during insect capture (bottom). Asterisks are positioned below calls for which spectrograms are shown. B, Network of input–output pathways that connect the SC with the sonar vocal production circuitry. Lemniscal (black arrow, top) and paralemniscal (gray arrow, at side) auditory inputs are integrated in the SC, which in turn projects to the laryngeal motor neurons indirectly via a tecto-tegemento-bulbar pathway. C, Top view drawing of the bat brain showing the dorsomedial position and relative size of the superior colliculus compared with adjacent structures. CBR, Cerebrum; CBL, cerebellum. Scale bar, 5 mm. D, Photograph of a 15 g bat with chronic implant before recording session. The small interface board mates with a removable amplifier head-stage board.