Stimulus control of cocaine self-administration.
Clear signals can turn drug taking on, slow it down, or stop it, just like food-reinforced behavior.
01Research in Context
What this study did
Scientists worked with rats that could press a lever to get cocaine.
They set up three lights: red, green, and no light.
Each light meant a different rule. Red = press whenever you want (VI). Green = wait 20 s or lose the chance (DRO). No light = no drug (extinction).
The rats learned these rules in 30-minute sessions, just like they would for food.
What they found
When the red light came on, the rats pressed fast and steady.
Under the green light they waited, then pressed once every 20 s.
During no-light periods, pressing almost stopped.
The same pattern happened earlier when the reward was food, showing true stimulus control.
How this fits with other research
Hoffman et al. (1966) first showed that two training tones can create twin peaks of suppression; Madden et al. (2003) now proves the same control works for drug taking.
Hart et al. (1974) used the same VI-DRO-extinction mix and saw wheel running rise when lever pressing fell. The new study keeps the schedule but swaps the reward for cocaine and still gets clean stimulus control, proving the earlier ‘adjunctive’ drop was about the schedule, not the food.
Okouchi (2003) tested humans with line lengths the same year and found classic generalization slopes. Together, the three papers show that stimulus control principles hold across species, reinforcers, and procedures.
Why it matters
If lights can steer cocaine taking in rats, then cues can steer human drug use. Put simply, change the cue, change the behavior. In clinic or home, you can teach clients to spot their ‘red-light’ situations and switch to a ‘green-light’ wait rule. Start small: pick one context, add a clear signal, and reinforce waiting.
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02At a glance
03Original abstract
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.
Journal of the experimental analysis of behavior, 2003 · doi:10.1901/jeab.2003.79-111