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. Author manuscript; available in PMC: 2019 Dec 22.
Published in final edited form as: Behav Neurosci. 2017 Feb 20;131(2):155–167. doi: 10.1037/bne0000185

Figure 1.

Figure 1.

Experimental design. (A, B) Outline of the experimental procedure. Phase 1 involved 2 × 1-hr magazine training sessions where one food pellet was delivered noncontingently every 2.5 min. In Phase 2, rats were trained to self-administer food pellets during 12 × 1-hr fixed-ratio 1 (FR-1) sessions where each lever press resulted in a 10-s conditioned stimulus (appetitive conditional stimulus [CS]) followed by a food reward and a 20-s timeout (TO) period. In Phase 3, rats had 2 × 1-hr punishment sessions where 25% of reinforced responses resulted in the presentation of the appetitive CS compounded with a novel aversive CS for 10 s followed by a 0.5-mA footshock, a food pellet, and a 20-s TO. The remaining 75% were identical to Phase 2. In Phase 4, rats were exposed to either the appetitive CS or the aversive CS during a 1-hr extinction test where neither food nor footshock was available.