Figure 1.

Classical conditioning of orientation discrimination. A, Experimental setup. Head-fixed mouse on a spherical treadmill in front of a monitor showing oriented gratings. Reward was delivered through a drinking spout equipped with a lick sensor. B, Discrimination learning paradigm. At irregular intervals, one of two oriented gratings was presented at a randomly selected contrast level. White arrow indicates the drift direction of the grating. The presentation of one grating (315 degrees) was immediately followed by a fluid reward; the other grating (45 degrees) had no consequences. C–E, Licking behavior of one animal in three example sessions at different learning stages (Mouse M22). Top, Licks to the rewarded stimulus. Bottom, Licks to unrewarded stimulus. Vertical bars represent stimulus onset and offset. E, Horizontal bars represent the time windows used to quantify the strength of anticipatory licking.