Fig. 5.

Performance (mean ± SEM) of (A) orienting responses (ORs; rear) and (B) food cup entry responses during the first and second halves of the pre-test session (p1 and p2, respectively) and the 10 conditioning sessions of experiment 2. Rats received either unilateral orexin-saporin lesions of lateral hypothalamus (LH; open symbols) or sham lesions of that region (filled symbols). The rats in groups sham and LH received light–food pairings, whereas the light was unpaired with food in group sham-U. Responding during conditioned stimulus (CS) presentations (solid lines) and prior to CS presentations (pre-CS, dotted lines) are shown separately. Rats with lesions of LH failed to acquire conditioned ORs, but were unimpaired in their acquisition of food cup responses and the initial performance of unconditioned ORs.