Fig. 4: Chronic CORT reduces active lever presses and breakpoint ratio in the progressive ratio test. | Translational Psychiatry

Fig. 4: Chronic CORT reduces active lever presses and breakpoint ratio in the progressive ratio test.

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

Fig. 4

a After completing outcome devaluation and contingency degradation tests, Vehicle (n = 19) and CORT (n = 26) mice were trained for 3 sessions on a variable ratio 3 (VR3) schedule and then tested in progressive ratio in 3 sessions separated by 2 days, under a linearly increasing, X + 4 (1, 5, 9, X + 4) progressive ratio schedule. b Chronic CORT reduced total active lever presses compared to Vehicle in all 3 sessions (p < 0.001). c Chronic CORT similarly reduced last ratio reached in all 3 sessions (p < 0.001). Values plotted are mean ± SEM. *p < 0.001. Taken together, chronic CORT reduces motivation to expend effort for food pellet reinforcers by reducing lever presses and breakpoint in three progressive ratio tests.

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