Figure 1.

Behavioral task performance. A, Schematic diagram of the Right-Left Pedal task. The rats pushed down on both pedals for a short period (≥1 s) to initiate the trial, and then voluntarily chose either of the pedals to receive a reward (e.g., left release). This task consisted of two blocks (the right pedal- and left pedal-rewarded blocks), which were alternated after meeting the criteria (see Materials and Methods). Photographs show the right-left pedal device installed in a stereotaxic frame and a rat manipulating (pushing down) both pedals. B, Typical example of task performance and the rats' learning process. Top, Rat chose the correct pedal based on the reward. Large and small colored vertical bars (red represents right choice; blue represents left choice) indicate correct and incorrect trials, respectively. The choice rate of the right pedal (purple line) was calculated by averaging the number of right choices obtained from the past 10 trials. Bottom, On training day 14, the rats chose the rewarded pedal >75% (left), and choice bias disappeared throughout the training (right). Solid line indicates average. Dashed lines indicate individual rat. C, Right-left pedal trajectories and EMG activity in left forelimb. Top, Example pedal and EMG traces in three consecutive trials. Bottom, Averaged population EMG power (± SEM) aligned with the onset of pedal release (dashed line).