Extended Data Figure 4: Data related to Fig. 4, and effects of optical excitation on naive mice and CRF–ChR2 mice during retrieval.

a, Top, positions of fibre tips for CRF⁺ and SOM⁺ gain-of-function groups. Placements were determined using standard histological techniques and lesions were matched to a mouse brain atlas. Mouse brain figure reproduced with permission from ref. 31. b, Single-unit recordings from identified CEl units in behaving mice. Units were isolated and identified as described (see Fig. 3, Extended Data Fig. 3 and Methods). The light was switched on four times for 10 s (see Methods). Shown for each group is a raster plot of an example neuron above and a peri-event histogram of the average firing rate below. The light protocols were effective in exciting both neuronal subclasses. c, Average speed traces from naive mice given four, 10-s light stimulations (CRF control, n = 10; CRF–ChR2, n = 7; SOM control, n = 7; SOM–ChR2, n = 7). Blue light caused a decrease in speed in the SOM–ChR2 group. d, Flight and freezing values for naive mice given four, 10-s light stimulations. ChR2-mediated excitation of SOM⁺ cells induced freezing behaviour (two-tailed paired t-test, CRF–ChR2 and SOM–ChR2; Wilcoxon matched-pairs signed-rank test, CRF control and SOM control). Horizontal lines indicate the mean. e, Flight and freezing values for individual CRF control (left) and CRF–ChR2 (right) mice shown in Fig. 4d (two-tailed paired t-test for CRF control freezing, CRF–ChR2 flight, CRF–ChR2 freezing. Wilcoxon matched-pairs signed-rank test for CRF control flight). Horizontal lines indicate the mean. f, Flight and freezing values for individual SOM control (left) and SOM–ChR2 (right) mice shown in Fig. 4d (two-tailed paired t-test). Horizontal lines indicate the mean. g, The CRF–ChR2 (n = 7) and GFP control (n = 10) groups were subjected to the conditioned flight paradigm. They were placed into the neutral context on day 4 (retrieval) and the SCS was played eight times. On four of the trials, the blue light was turned on during the entire SCS. Left, flight and freezing values for individual mice in the CRF control group (flight scores: Wilcoxon matched pairs signed-rank test; freezing scores: two-tailed paired t-test). Middle, flight and freezing values for individual mice in the CRF–ChR2 group (two-tailed paired t-test). Horizontal lines indicate the mean. Right, average change in freezing and flight between light and no-light conditions. CRF⁺ excitation significantly reduced conditioned freezing (two-tailed unpaired t-test). Box and whisker plots indicate median, interquartile range, and 5th to 95th percentiles of the distribution. Crosses indicate means. All other values are means ± s.e.m., except as indicated.

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