Figure 1.

Experimental setup and image tracking. A, Top view of the behavioral setup. Two cameras were orthogonally positioned so as to obtain a bird’s-eye view and a side view of the search space. The shaded arc represents the possible reward locations, beginning 5 inches from the center of the tunnel and spanning three inches radially outward. B, Representative video frame illustrating the manual tracking procedure. Small black dots are points tracked on the initial linear portions of the rostral- and caudal-most whiskers. Large white dots are points tracked to quantify the head angle. Image has been black–white reversed for visual clarity. C, Coordinate systems used to quantify whisker angles. World coordinates are simply standard Cartesian coordinates. Snout coordinates are fixed to the head of the rat. Asterisks indicate the tracked angles in both coordinate frames. Thick black lines labeled “m” represent the mid-array angle calculated by averaging the positions of the rostral- and caudal-most whiskers. D, A schematic of a typical whisk representing the morphological whisk parameters listed in Table 1. Pro, Protraction; Ret, retraction.