An extinction cue reduces spontaneous recovery of ataxic ethanol tolerance in rats

Ethanol ataxia experiments with rats investigated cue effects on conditioned tolerance. Spontaneous recovery (SR) was assessed 1 day and 18 days after extinction with conditioned stimuli (CSs) paired or unpaired with an ethanol unconditioned stimulus (US). Behavioral tolerance was assessed by not tilting the apparatus during conditioning. Non-associative processes were assessed post-conditioning with or without a buzzer cue. Bouton's (1993, Psychol Bull 114:80-99) memory theory was tested using an extinction cue and an associatively neutral cue presented during SR testing.

Tolerance was conditioned to a room + strobelight CS by ethanol injections experienced on a tilting floor (standard conditioning). Controls received no ethanol or ethanol, either during the CS without the floor tilting or 11 h post-CS. SR testing occurred 1 day or 18 days after extinction (experiment 1). Conditioning was followed by tolerance and CR tests either with or without a 15-s buzzer cue (experiment 2). In extinction, the CS and cue occurred without ethanol; the cue occurred before 7% or none of the extinction trials. Testing occurred 18 days after extinction with or without that cue (experiment 3), or with an equally familiar ("neutral'') cue presented before conditioning (experiment 4).

Tolerance developed without floor tilting. CS-US unpairings prevented tolerance. Tolerance SR occurred 18 days but not 1 day after extinction only after CS-US pairings (experiment 1). Post-conditioning tests showed no unconditioned effects of the cue (experiment 2). Testing with no cue 1 day after extinction with the cue resulted in no tolerance increase. The extinction cue reduced SR (experiments 3 and 4); the neutral cue did not (experiment 4).

Cues correlated with extinction reduce SR. Non-associative and practice processes, Bouton's (1993, Psychol Bull 114:80-99) memory theory, alternative interpretations, and clinical implications are discussed.