Figure 2.

An opportunity for incentive learning is required for food deprivation to affect reward-seeking actions. Rats, either 3 h (control) or 23 h food deprived, were either exposed to the sucrose outcome or left unexposed before testing under nonrewarded conditions. Seeking-lever press rate was normalized to responding during the training session immediately before the exposure/nonexposure phase in each case. A, Normalized seeking response rate for the unexposed and exposed groups averaged over the entire 5 min nonrewarded test session. B, Seeking response rate data, normalized to baseline, over the time course of the 5 min session for the nonexposed group. C, Seeking response rate data, normalized to baseline, over the time course of the 5 min session for the reexposed group. Error bars indicate ± SEM. *p < 0.05.