Figure 8.

DRN stimulation bidirectionally modulates the responses of OFC neurons to the expectation of natural reward. A–D, Raster plots and peristimulus time histograms of four representative OFC neurons that were modulated by optogenetic stimulation of the DRN Pet-1 neurons during the period of sucrose solution delivery. Odor 1 was coupled to sucrose solution and laser stimulation of the DRN Pet-1 neurons at 20 Hz for 2 s, whereas Odor 2 was coupled to sucrose solution alone. A, B, The examples show that DRN stimulation could potentiate excitatory responses (A) and inhibitory responses (B) to sucrose delivery. C, D, We also observed attenuation effects of DRN stimulation on excitatory responses (C) and inhibitory responses (D) to the expectation of sucrose solution delivery. E, Scatterplot showing the strengths of the OFC responses to the two conditioned odorants (n = 245 neurons). The AUC values were calculated by comparing the differences between the firing rates of the OFC neurons during the delay time window. The colored dots represent neurons with significant selectivity for the CS+ trials (red) and the CS− trials (permutation test, p < 0.01). F, The bar graph showing the distribution of OFC neuronal selectivity. G, Cumulative probability of the variances of the OFC neuronal responses to the two conditioned odorants. Variance was determined by measuring the Euclidean distance of each point from the nonselective line. The blue line was calculated from the data shown in E, and the black line was calculated from the control data shown in Figure 1E. The mean variances of both cases are plotted in the right panel, and statistical significance was determined with a Kolmogorov–Smirnov test (p = 7.4 × 10⁻⁷). H, Mouse licking responses during the recording sessions (n = 43 sessions from four mice).