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. Author manuscript; available in PMC: 2022 Aug 6.
Published in final edited form as: Nat Neurosci. 2021 Feb 15;24(3):391–400. doi: 10.1038/s41593-020-00791-4

Figure 3. LH GABAergic neurons are recruited to encode fear memories only in rats that experience contingencies between cues and rewards.

Figure 3.

Responding is shown as mean level of responding (%; ±SEM) during Exp 3. Top: LH GABAergic neurons were inhibited (green rectangle) during fear learning in rats with a prior history of reward learning. (A) Prior to aversive learning, rats were trained to associate a light with food delivery in context A, with no differences between NpHR learners (n=6 rats) and eYFP learners (n=6 rats; session: F4,40=11.171, p=0.000; session x group: F4,40=0.174, p=0.951; group: F1,10=1.498, p=0.249). (B) During fear learning, we found that NpHR learners showed less learning about the tone, and greater learning to the context (simple main effect after group interaction: F1,20=4.831, p=0.040), in contrast to eYFP reward learners (F1,20=0.773, p=0.390). (C) The deficit in learning about the tone was maintained in extinction test, after extinction to the contextual cues, with LH GABAergic neurons intact (group: F1,10=6.085, p=0.033). Bottom: LH GABAergic neurons were inhibited (green rectangle) during fear learning in rats that received light presentations without reward. (D) Prior to aversive learning, NpHR naïve (n=6 rats) and eYFP naïve (n=6 rats) group received presentations of the light and did not acquire an appetitive response across days (session: F4,40=0.498, p=0.737; session x group: F4,40=0.951, p=0.445; group: F1,10=0.263, p=0.620). (E) During fear learning, NpHR naïve rats without LH GABAergic activity showed no difference in freezing to the tone and contextual cues (F1,20=0.435, p=0.517), similarly to eYFP naïve rats (F1,20=0.048, p=0.828). (F) There was no difference in the expression of fear to the tone during the subsequent extinction test when LH GABAergic neurons were intact (group: F1,10=0.303, p=0.594). Data were analyzed with a repeated-measures ANOVA, where analyses of simple-main effects were warranted after a significant interaction was determined and did not necessitate controls for multiple comparisons. In the case of an expected interaction, one-tailed tests were used to warrant investigation of further simple-main effects.