Discover how chlordiazepoxide facilitates the extinction of learned behaviors and what this reveals about the brain's inner workings.
Why is it so difficult to break habits, even when we're motivated to change? Whether it's reaching for unhealthy snacks, checking our phones constantly, or other persistent behaviors, the answer may lie in how these patterns were originally learned—and more importantly, how they can be unlearned.
Recent scientific research has revealed fascinating insights into this challenge, demonstrating that different patterns of reward make behaviors more or less resistant to change. Even more surprisingly, scientists have discovered that a common anti-anxiety medication can significantly help overcome stubborn behaviors.
This article explores the groundbreaking research on how chlordiazepoxide facilitates the extinction of learned behaviors and what this reveals about the brain's inner workings.
In operant conditioning, behaviors are strengthened when followed by reinforcement. However, not all reinforcement is created equal. The pattern by which rewards are delivered, known as a "reinforcement schedule," significantly impacts how quickly a behavior is learned and how resistant it is to extinction—the process by which a behavior diminishes when no longer rewarded 3 .
Interestingly, behaviors learned through partial reinforcement—where rewards are delivered occasionally rather than every time—are significantly more resistant to extinction than those learned through continuous reinforcement 3 . This explains why gambling can be so addictive (variable-ratio schedule) and why employees paid based on weekly deadlines (fixed-interval schedule) often work in bursts rather than steadily 5 .
Operant extinction occurs when a previously reinforced behavior no longer produces the expected reward, eventually leading to a decrease in that behavior 4 . However, this process isn't always straightforward. When reinforcement is first withheld, behaviors often undergo an "extinction burst"—a temporary increase in frequency or intensity as the organism tests whether the reward contingency has changed 4 .
| Schedule Type | Description | Example |
|---|---|---|
| Fixed-ratio (FR) | Reinforcement after a set number of responses | Factory worker paid per item produced |
| Variable-ratio (VR) | Reinforcement after an unpredictable number of responses | Gambling on a slot machine |
| Fixed-interval (FI) | Reinforcement after a set time period has passed | Weekly paycheck |
| Variable-interval (VI) | Reinforcement after varying time periods | Checking for social media notifications |
To understand how reinforcement schedules affect the extinction process and how drugs might facilitate it, researchers conducted a sophisticated experiment using C57Bl/6 mice, a common strain in behavioral neuroscience research 1 .
The researchers designed a comprehensive study to investigate how chlordiazepoxide (CDP)—a benzodiazepine that potentiates GABAergic transmission—affects extinction following different reinforcement schedules 1 :
Mice were trained to press a lever for food rewards under one of three different reinforcement schedules:
Once the lever-pressing behavior was well-established, the researchers began extinction sessions where lever presses no longer produced food.
Mice were divided into three treatment groups:
This elegant design allowed researchers to examine both the schedule-dependency of CDP's effects and whether the timing of drug administration influenced its effectiveness.
The experiment yielded several important findings that advance our understanding of operant extinction 1 :
The extinction process proceeded more rapidly following fixed-interval training compared to fixed-ratio training, demonstrating that the pattern of reinforcement during learning significantly impacts how quickly behaviors diminish when rewards stop.
Chlordiazepoxide administration facilitated the extinction of operant behavior—mice receiving CDP showed more rapid reduction in lever pressing compared to controls.
The facilitation of extinction by CDP only occurred after a number of extinction sessions had taken place. This timing effect suggests that GABAergic processes may be involved in a second phase of extinction that occurs only after initial extinction learning.
CDP was effective following training on both ratio and interval schedules, indicating its effects generalize across different reinforcement contexts.
| Factor | Conditions Used in Study |
|---|---|
| Reinforcement Schedules | Fixed-Ratio 5 (FR 5), Fixed-Interval 11s (FI 11s), Fixed-Interval 31s (FI 31s) |
| Drug Administration | Vehicle throughout, CDP throughout, Vehicle first then CDP |
| Subject Population | C57Bl/6 male mice (common background for transgenic studies) |
| Extinction Sessions | 15 total sessions |
| Finding | Significance |
|---|---|
| Schedule Effect | Reinforcement history affects resistance to extinction |
| CDP Facilitation | GABAergic systems play a role in operant extinction |
| Time-Dependent Effect | Suggests multiple phases in extinction process |
| Schedule Independence | Effect generalizes across learning contexts |
| Research Material | Function in Study |
|---|---|
| C57Bl/6 Mice | Standardized subject population; common background for transgenic studies |
| Operant Chambers | Controlled environment for measuring lever-pressing behavior |
| Chlordiazepoxide (CDP) | Benzodiazepine that potentiates GABAergic transmission; experimental variable |
| d-Cycloserine (DCS) | NMDA receptor partial agonist; compared with CDP in related studies |
| Food Reinforcers | Positive reinforcement during training phases |
These findings have significant implications for understanding how we might better address persistent unwanted behaviors in humans. The research suggests that GABAergic systems in the brain play a crucial role in the extinction of learned behaviors, particularly after the initial phase of extinction has already begun 1 .
This may explain why simply removing rewards for problematic behaviors doesn't always lead to quick change—the brain may require different neurochemical conditions to efficiently extinguish well-established behaviors. The delayed effect of CDP observed in these studies suggests there might be sequential processes in extinction learning, with GABA becoming particularly important only after initial extinction learning has occurred.
Furthermore, comparing these findings with other studies reveals that different neurotransmitter systems appear to play distinct roles in operant extinction. While CDP (which enhances GABA transmission) is most effective when administered before extinction sessions, d-cycloserine (which affects glutamate systems) works best when given after sessions, suggesting it supports the consolidation of extinction learning 7 .
The research on reinforcement schedules and chlordiazepoxide represents an important bridge between behavioral psychology and neuroscience. By demonstrating that specific pharmacological interventions can facilitate the extinction process—and that this effect varies depending on how the behavior was originally learned—scientists are developing a more sophisticated understanding of behavior change.
These findings suggest that effectively addressing persistent unwanted behaviors may require considering both the reinforcement history of those behaviors and the neurochemical environment during extinction attempts. As research progresses, this work may lead to more effective treatments for conditions involving maladaptive persistent behaviors, from addictions to compulsive disorders.