Fig. 4.

Analysis of movement patterns near object-choice moments across learning stages. (A) The movement pattern for each rat across learning sessions. For a day's recording session, the rat's trajectories associated with object choices in either arm 3 or 5 were overlaid for illustration purposes. For each day's illustration, there are two black circles (each with x mark in the center) and they represent the locations of the two objects (corresponding to the food well locations) in the choice platform. Between the two black circles, the one associated with a dotted circle in magenta color indicates the object that was approached initially as the rat entered the choice platform (on the basis of trajectory analysis). The blue trajectories (direct push response, DPR) indicate that the rat actually pushed the object at the end of those movements (thus the first object encountered was pushed). The red trajectories (inhibition-and-push response, IPR) indicate that the rat did not push the first object encountered (thus inhibition of push behavior), but pushed the object on the opposite side instead. The numbers beneath the arm information indicate the ratio between the incidents of DPR and IPR. Note the increase in the proportion of IPR (with the decrease in DPRs) and the development of more stereotyped movement trajectories as the rats learned the task across days. (B) Histograms showing the distribution of traveling distances measured (in log scale) for the trajectories shown in A in the choice platform. Note the development of bimodal distributions toward the later learning session, indicating the increase in IPR.