Figure 6.

Sonar-related premotor activity is consistently observed in all recordings from SC. A, Raster of events (top) preceding the onset of sonar vocalizations during one trial (bat VTAD1). Ordinate represents consecutive sonar calls from first to last in the trial. Call onset is at t = 0 ms, and the raster extends from 60 ms before to 10 ms after sonar vocal onset. During this trial, 74 sonar calls were produced, and both long and short lead events were evident. A PMTH (bottom) representation of neural events. The dashed line shows the baseline activity level, and the solid line represents the criterion threshold (2 SD above mean baseline rate) used for determining change from baseline activity. A clear reduction in firing rate is observed between the long lead and short lead events and after call onset. B, The PI and sonar call duration of vocalizations produced during the trial shown in A. PI is generally long, >75 ms, in virtual target amplitude discrimination trials. C, Linear regression using the per call mean LLE time (〈LLE〉_TIME) as the single predictor for sonar call duration. The sonar calls (n = 1026 calls) come from one session (including the trial in A) and show only a marginal increase in 〈LLE〉_TIME with increasing call duration. D, Linear regression using the 〈LLE〉_spread (see Materials and Methods) for each call in one session as the single predictor of call duration. 〈LLE〉_spread shows a slight positive increase with call duration.