Fig 1: DREADDs-mediated manipulation of OFC neurons and additional analyses for optogenetic perturbation experiments.a, Mean number of errors per block committed by the animals injected with AAV8-hSyn-hM4Di-mCherry (left, n = 4 rats; a gift from Bryan Roth; Addgene viral prep # 44362-AAV8) five days prior to the beginning of perturbation experiments. The volume of 500 nL was injected at eleven sites in the OFC of each hemisphere with the following coordinates (AP, ML, and DV in mm): 2.7, 3.5, 5.2; 3, 2.5, 4.6; 3, 3.8, 4.4; 3.6, 2, 4.2; 3.6, 3.6, 4; 4.2, 1.4, 4.2; 4.2, 2.4, 4; 4.7, 1.6, 3; 4.7, 2.8, 3.5; 5.2, 1.2, 2.6; and 5.2, 2.6, 2.6. To evaluate the effects of manipulation, a microdrive with two circular bundles of 6 movable tetrodes each was implanted bilaterally with the centres of the bundles positioned at 3.5 mm (AP) from bregma and 1.5 mm (ML) from midline. Total errors and the two major error types — prior block errors and current block errors (defined in Extended Data Fig. 1)— are plotted. Shown are means ± s.e.m. b, Top: coronal section showing expression of hM4Di-mCherry in bilateral OFC. Bottom: normalized firing rates of OFC neurons over time relative to the subcutaneous injection of Agonist 21 (DREADDs Agonist 21 dihydrochloride, 7.04 mg/mL [20 mM]; Hello Bio at a dose of 6 mg/Kg). Means (solid) ± s.e.m. (shaded) across 100 neurons. c, Average speed of the animals expressing hM4Di-mCherry during motion (speed > 10 cm/s) when injected with saline versus Agonist 21. Black oblique lines represent paired sessions (see Methods). d, Plot shows the number of errors per trial block in the saline (grey) or Agonist 21 (red) injected sessions. The animals were injected with Agonist 21 followed by at least 45 min waiting time to allow the drug to reach the brain and take effect before starting the behaviour sessions. On control days, the equal volume of 0.9% saline solution was injected. To evaluate the impact of OFC silencing, the same sequences of well combinations were tested in a pair of saline and Agonist 21 sessions. The two sessions were carried out on consecutive days in a randomized order. All types of errors (left; ***p = 3.08 × 10−5 in two-sided Wilcoxon signed-rank test: z = −4.16) and the errors to the wells rewarded in the previous block (right; *** p = 3 × 10−4 in two-sided Wilcoxon signed-rank test: z = −3.61,) are shown separately. n = 23 sessions from 4 animals injected with AAV encoding hM4Di-mCherry. e, Mean number of errors per block committed by the animals injected with AAV1-CamKII-bReaCh-ES-eYFP five days prior to the start of perturbation experiments. Shown are means ± s.e.m. (n = 3 rats). f, Average error rates following consecutive correct licks in a block one day before and after the optogenetic perturbation experiments. The horizontal axis indicates the number of consecutive correct trials prior to the trial being evaluated. All the three animals made no errors after 4 consecutive correct trials, and thus we performed optogenetic perturbations after the first four consecutive correct trials in a block. Furthermore, after the termination of perturbation, the animals still did not make any errors after four consecutive correct trials, suggesting that this criterion is most likely valid during the entire course of perturbation experiments. Shown are means ± s.e.m. (n = 3 rats). g, Average running speed of the animals expressing bReaCh-ES-eYFP during the laser pulses of 40-s duration (left; running speed: laser on 33.54 ± 1.18 cm/s, laser off 34.37 ± 0.68 cm/s; p = 0.38 in two-sided Wilcoxon signed-rank test; n = 12 sessions; analyses were restricted during motion [speed > 10 cm/s]) or 6-s duration (right; running speed: laser on 33.4 ± 0.86 cm/s, laser off 34.85 ± 0.92 cm/s; p = 0.074 in two-sided Wilcoxon signed-rank test; n = 9 sessions). Each point in the plots represents the average speed from one session. h, Histogram of the times of either laser onsets relative to lick onset (left) or laser ends relative to lick end (right) in the experiments with 6 s optogenetic perturbation at lick onset. The vertical axis indicates the number of laser events, and the horizontal axis represents time relative to lick onset (left) and lick end (right). 98% (102 out of 104) of laser onsets occurred after lick onset and 83.65% (87 out of 104) of laser pulses ended before lick end. i, Histogram of the times of laser onsets relative to either lick end (left) or motion onset (right) in the experiments with 6 s optogenetic perturbation at motion onset. 91.79% (123 out of 134) of laser onsets occurred after lick end, and 95.52% (128 out of 134) of laser pulses started within 100 ms relative to motion onset. Three laser events that started 5 s after lick end, as well as six laser events that started more than 6 s prior to motion onset, were excluded from the plots.