Operant conditioning teaches drug users that taking a drug produces pleasure. As a result, drug users take more of the drug. Because drugs of abuse directly activate the brain reward system, the positively rewarding qualities of the drug powerfully reinforce drug-taking behavior. Operant conditioning also teaches drug users that a drug can relieve unpleasant feelings, such as anxiety and stress. So, people learn to take the drug to relieve these negative feelings. The result is that negative reinforcement teams up with positive reinforcement to "team-teach" drug self-administration. And this all happens unconsciously. Users are not aware of the lessons they are learning. Operant conditioning occurs each time a drug is used. The lesson it teaches—keep taking drugs—is therefore well learned.
How Tolerance, Physical Dependence, and Psychological Dependence Interact With Learning
As drug users consume more of a drug, they develop tolerance. To overcome tolerance, they increase the dose of the drug. Gradually, as they take higher and higher doses and use the drug more frequently, they discover that they need the drug just to feel normal. At this point, they have become physically dependent. Their brains and bodies have adapted to the drug and cannot function "normally" without it. If these drug users stop drug use, even for a short period of time, withdrawal symptoms appear. The more intense withdrawal becomes, the worse users feel. But, as soon as they take the next dose, they feel better.
The relief from withdrawal symptoms produces an especially potent form of negative reinforcement. So, having become physically dependent on a drug by abusing it, the user creates a situation in which he or she must then take that drug to prevent or eliminate even worse stresses— the anxiety, the flu-like symptoms of physical discomfort, and the cravings—that begin as soon as the last dose of a drug has worn off. This negative reinforcement becomes an especially important mechanism in maintaining addiction in people who use opiates, alcohol, and depressants.
As drug users integrate their drug use ever more deeply into their lives, they eventually develop psychological dependence, believing they can no longer live without the drug. They have to have their drug. When this happens, the drug user has become a drug addict.
Addiction involves still another kind of learning—classical conditioning. Drug addicts learn to associate any number of neutral stimuli with the reward induced by drug-taking. These stimuli can include almost anything. For example, the sight of drug paraphernalia quickly elicits craving in abstinent addicts. Moreover, places (the car), activities (finishing dinner), simple items (a $10 bill), and people (the drug dealer) can have the same effect. Pretty soon, simply through the associations produced by classical conditioning, these stimuli themselves elicit measurable biological responses and drug craving.
Neutral stimuli that elicit drug craving are called "cues" or "triggers." For Henry, the process of shooting up began when he first received a glassine envelope containing a glistening white powder from a dealer. After many years, the simple sight of the glassine envelope, and then the powder, including its smell, became classically conditioned cues for Henry. While he was using heroin, Henry became excited as soon as he saw them, and he rushed to dissolve the powder, draw it into his syringe, and shoot it into a vein. Henry got excited because, to him, that white powder meant that he was about to get high. Even months after entering treatment, the sight of any white powder still makes Henry want to get high. He doesn't know why, but for him, white powder, such as confectioner's sugar, still makes Henry want to get high.
The power of classical conditioning is hard to underestimate. A drug addict like Henry—or Sybil, who smoked several dozen cigarettes each day—will have hundreds to thousands of trials associating drug use with other, formerly neutral, stimuli. Although they can be muted, these associations can never really be unlearned. They are always lurking, creating the risk of relapse, with the power to elicit craving even years after an addict has successfully withdrawn from the drug.
Explicit Learning and Memory
Still another kind of learning is involved in addiction. It is the conscious, explicit learning that produces most of our conscious memories. Drug users remember the pleasure and relief produced by drugs, and those prized memories can also produce a longing to use drugs again.
In many ways, explicit learning is the easiest kind of drug-related learning to overcome. The memories created by explicit learning are stored in the cerebral cortex and are available to consciousness. Memories created by either operant or classical conditioning remain outside of, and unavailable, to consciousness. But drug users can bring explicit memories directly into conscious aswareness to analyze and compare them with other pertinent information.
People can contrast a pleasant memory of drug use with information about the not-so-pleasant consequences of drug use. A memory of drinking some nice wine in a favorite restaurant, which may lead a recovering alcoholic to consider drinking again, can be directly overridden by the knowledge (another memory) that drinking produces horrible consequences for this particular person. He or she can then use reason and make a rational decision not to drink.
Continue reading here: Drugs Take Behavioral Control Away From The Cerebral Cortex
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