Figure 7.

Premotor neuronal activity recorded in the SC during a single oscillating target trial. A, Raster and perimotor time histogram show a pattern of premotor activity similar to that observed in virtual target amplitude discrimination recordings. LLEs and SLEs precede sonar vocalizations with a reduction toward baseline activity rates between the two event groups. Data are aligned to sonar call onset (lead time of t = 0 ms). LLEs in the raster show a tendency toward shorter lead times during the trial and correspond to times when the target is approaching the bat. B, PI (gray, filled), start (black, filled), and end (black, open) frequency, call duration (black, open), and target distance (black, filled) of sonar vocalizations produced during trial shown in A. The oscillating target approaches and recedes from the bat twice in this trial. Each sonar call parameter is modulated as a function of the target distance. Sonar call duration and pulse interval are clearly decreased whenever the target approaches. C, Linear regression using the per call mean LLE time (〈LLE〉_TIME) as the single predictor of sonar call duration for all sonar calls in one recording session (n = 738 calls). The data show an increase in 〈LLE〉_TIME for increasing sonar call durations (r = 0.73). D, Reduction in the correlation between sonar call duration and 〈LLE〉_TIME when 〈LLE〉_TIME is not associated with the call it precedes. Each panel shows the sonar call duration versus the 〈LLE〉_TIME using the data from C. Except for the top left, the other panels show the data with 〈LLE〉_TIME associated with the sonar call duration one, three, and five calls ahead in the vocal sequence. r values are regression coefficients.