A nontrivial forelimb reach-and-grasp task for the rat.

<p>Adult rats were trained to perform either a forelimb reach-and-grasp task (<i>Reach</i> groups) or a sham version of the task (<i>Sham</i> groups) for either 5 days (<i>Reach</i>, N = 4; <i>Sham</i>, N = 4) or 12 days (<i>Reach</i>, N = 4; <i>Sham</i>, N = 4) before tissue harvest. <i>A</i>, Behavioral setup for the <i>Reach</i> groups. In each trial a food pellet was placed at one of six possible slots arranged in three rows at different distances from the animal (near, mid, and far slots) and two columns that were ipsilateral and contralateral to the animal's preferred limb, respectively. The task goal was to reach and grasp the pellet using the preferred limb with single or multiple reaches. A reach was defined to be any hand trajectory from the box to the shelf area that crossed the border between the box and shelf (indicated by the thick black horizontal line), and then back to the box by crossing the same line. <i>B</i>, Behavioral setup for the <i>Sham</i> groups. In each trial the pellet was placed in the slit. Because the pellet was easily accessible, the rat naturally retrieved the reward with its tongue without using its forelimb. In all groups, the animal was conditioned to initiate a new trial by turning down either the left (left-handed rats, dotted-line arrows) or right (right-handed rats, solid-line arrows) aisle from the central aisle.