Flexible Coupling of Respiration and Vocalizations with Locomotion and Head Movements in the Freely Behaving Rat

Figure 7

Disruption of coupling between respiration and head/body movements during vocalizations. (a) Distribution of emitted ultrasound with the phase of the respiration and acceleration oscillations for each behavior mode. The vertical axes represent how many times the rats emitted ultrasound at each phase of each oscillation. The histogram covers two cycles for clarity. As a guide to read these plots, note that the rats almost never emitted ultrasound while the respiration was between its peak exhalation and the following peak inhalation. A total number of USVs detected were 1089 (sniffing), 500 (walking), 938 (trotting), and 54 (galloping). Note that phases between the respiration and acceleration are not matched, since each one was aligned to its own peak. (b) Phase Locking Values for respiration at the times of (left) and (right) peaks for all acceleration cycles (black), only those that did not coincide with emission of vocalizations (blue), or only those that did (red). We included in sniffing those during lingering (detailed in Figure 3) and those during walking (detailed in Supplementary Figure 1). There were not enough cycles during galloping episodes to segregate by vocalizations. (c) Phase locking of respiration to (left) and (right) peaks during trotting and sniffing. Values with no significant phase locking are depicted with open symbols (Rayleigh test, alpha = 0.05/26 = 0.002). (d) Example of trotting with high vocal production from a male rat. Top: sonogram of the recorded ultrasound (dark is high power). Bottom: respiration, vocalization times, and frontwards () and upwards () head acceleration (colors as in Figure 4(a)). Gray solid line is speed (max. 0.79 m/s) and dashed lines mark the time of exhalation peaks. The rat is doing fast respiration and then starts a progression while emitting long vocalizations of the “split” class, which were found to coincide with fast progressions in a separate set of recordings (to be published elsewhere). Note that during long vocalizations respiration appears decoupled with head acceleration. (e) Example of trotting without vocalizations for the male rat under high-speed video (max. speed 0.5 m/s). Note that peaks appear to align with the transition from inhalations to exhalations.

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