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[Preprint]. 2023 Aug 19:2023.03.13.532469. Originally published 2023 Mar 14. [Version 2] doi: 10.1101/2023.03.13.532469

Figure 4. Strong aversive experience drives Neutral ∩ Aversive ensemble reactivation during Neutral context recall.

Figure 4.

A) Behavioral schematic of calcium imaging experiment, as in Figure 1D. Here, we focused on hippocampal activity during the Aversive, Neutral, and Novel recall sessions.

B) Cells active only during the Neutral experience and not the Aversive experience were more likely to be reactivated when mice were placed back in the Neutral context, compared to when they were placed in a Novel context (F1,12 = 24.44, p = 0.0003). There was no effect of shock amplitude (F1,12 = 3.08, p = 0.10) (Low Shock, N = 6 mice; High Shock, N = 8 mice).

C) Cells active during the Aversive experience and not the Neutral experience were no differently reactivated in Neutral vs Novel contexts. (Amplitude: F1,12 = 0.029, p = 0.869; Context: F1,12 = 1.39, p = 0.261; Amplitude x Context: F1,12 = 0.14, p = 0.71) (Low Shock, N = 6 mice; High Shock, N = 8 mice).

D) Cells active during both the initial Neutral and Aversive experiences were subsequently more likely to be reactivated in the Neutral context compared to Novel context in High Shock mice (t7 = 8.53, p = 0.00012), but not Low Shock mice (t5 = 0.55, p = 0.61; Context x Amplitude: F1,12 = 10.33, p = 0.007) (Low Shock, N = 6 mice; High Shock, N = 8 mice).

E) In High Shock mice, population activity patterns in the Neutral context changed significantly from Neutral encoding to Neutral recall (Amplitude: F1,12 = 5.65; SessionPair: F1,12 = 10.42; Amplitude x SessionPair: F1,12 = 6.22). During Neutral recall in High Shock mice, population activity vectors were less correlated with the average Neutral encoding population vector than Aversive recall activity was with the average Aversive encoding population vector (t7 = 4.10, p = 0.009). Neutral encoding-to-recall correlations were also lower in High vs Low Shock mice (t6.92 = 2.98, p = 0.042). Aversive encoding-to-recall correlations were no different in High vs Low Shock mice (t6.11 = 1.13, p = 0.30). In Low Shock mice, Neutral and Aversive encoding-to-recall correlations were no different (t5 = 0.23, p = 0.83) (Low Shock, N = 6 mice; High Shock, N = 8 mice).