Fig. 3: Chronic CORT impairs outcome devaluation after limited instrumental conditioning, but not extended training. | Translational Psychiatry

Fig. 3: Chronic CORT impairs outcome devaluation after limited instrumental conditioning, but not extended training.

From: Chronic corticosterone administration induces negative valence and impairs positive valence behaviors in mice

Fig. 3

a Training groups (treatment after and treatment throughout training) were collapsed into treatments (Vehicle and CORT) after initial instrumental acquisition. Mice were tested for satiety-specific outcome devaluation and contingency degradation after both extended and limited-training, to test for the effect of chronic CORT on sensitivity to a devalued or degraded outcome, and whether goal-directed or habitual mechanisms are guiding behavior. b Vehicle (n = 19) and CORT (n = 26) mice did not differ in lever pressing in extinction test sessions after satiety-specific outcome devaluation (p > 0.05). c Vehicle (n = 19) and CORT (n = 26) mice similarly reduced lever pressing on a degraded response lever (p < 0.001 for both treatments), but not on a non-degraded lever (p > 0.05), suggesting extended-training similarly degraded responding on one lever in both treatments, as the lever was degraded for 3 degradation sessions. d Next, a separate cohort of Vehicle (n = 10) and CORT (n = 10) mice were trained in a shorter protocol before satiety-specific outcome devaluation and contingency degradation, to examine if the extended-training protocol led to over-training. e After 1-h free access to reinforcer pellets (devalued), or standard lab chow (valued), limited-training led to a reduction in lever pressing in the devalued condition in Vehicle mice (p = 0.007) but not in CORT mice (p = 0.144), suggesting CORT reduces sensitivity to a devalued outcome after limited training. f However, limited training did not lead to reduced responding for a degraded outcome like shown with extended-training in either Vehicle (p = 0.247), or CORT (p = 0.156) mice. Values plotted are mean ± SEM. *p < 0.05, **p < 0.001. Taken together, chronic CORT reduces sensitivity to a devalued outcome after limited trained, without influencing contingency degradation, while extended-training shifts behavior to habitual responding in both treatments.

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