Whisking mediated touch is an active sense whereby whisker movements are modulated by sensory input and
behavioral context. Here we studied the effects of touching an object on whisking in head-fixed rats.
Simultaneous movements of whiskers C1, C2, and D1 were tracked bilaterally and their movements compared.
During free-air whisking, whisker protractions were typically characterized by a single
acceleration-deceleration event, whisking amplitude and velocity were correlated, and whisk duration
correlated with neither amplitude nor velocity. Upon contact with an object, a second acceleration-deceleration
event occurred in about 25% of whisk cycles, involving both contacting (C2) and non-contacting (C1, D1) whiskers
ipsilateral to the object. In these cases, the rostral whisker (C2) remained in contact with the object throughout
the double-peak phase, which effectively prolonged the duration of C2 contact.
These "touch-induced pumps" (TIPs) were detected, on average, 17.9 ms after contact.
On a slower time scale, starting at the cycle following first touch, contralateral amplitude increased while
ipsilateral amplitude decreased. Our results demonstrate that sensory-induced motor modulations occur at various
timescales, and directly affect object palpation.