Weiss, S. J., Kearns, D. N., Cohn, S. I., Schindler, C. W., & Panlilio, L. V. (2003).
Stimulus control of cocaine self-administration.
Journal of the Experimental Analysis of Behavior,
79, 111-133.
Environmental stimuli that set the occasion wherein drugs are
acquired can ``trigger'' drug-related behavior. Investigating the
stimulus control of drug self-administration in laboratory
animals should help us better understand this aspect of human
drug abuse. Stimulus control of cocaine self-administration was
generated here for the first time using multiple and chained
schedules with short, frequently-alternating components - like
those typically used to study food-maintained responding. The
procedures and results are presented along with case histories to
illustrate the strategies used to produce this stimulus control.
All these multicomponent schedules contained variable-interval
(VI) components as well as
differential-reinforcement-of-other-behavior (DRO) or extinction
components. Schedule parameters and unit dose were adjusted for
each rat to produce stable, moderate rates in VI components, with
minimal postreinforcement (infusion) pausing, and response
cessation in extinction and DRO components. Whole-body drug
levels on terminal baselines calculated retrospectively revealed
that all rats maintained fairly stable drug levels (mean, 2.3 to
3.4 mg/kg) and molar rates of intake (approximately 6.0
mg/kg/hr). Within this range, no relation between local VI
response rates and drug level was found. The stimulus control
revealed in cumulative records was indistinguishable from that
achieved with food under these schedules, suggesting that common
mechanisms may underlie the control of cocaine- and
food-maintained behavior.
Key words: stimulus control, drug self-administration, multiple schedules,
chained schedules, cocaine, whole-body drug levels, lever pressing, rats