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The experiments conducted using Rat Park were designed to examine whether an addiction to drugs is a neurophysiological phenomenon, or whether the repeated misuse of drugs, particularly illegal drugs, is largely or entirely a response to unhappiness and poor living conditions.

In the 19th century, drug addiction was regarded as a sign of akrasia, or weakness of the will, as well as an indication of low intelligence or a weak character. The 21st century view is based on the prevailing biological reductionist or physicalist model: Addiction to a drug is a byproduct of the chemical structure of the drug itself, the theory goes, not a sign of moral weakness.

The issue is a contentious one for three reasons:

First, it throws up two philosophicalPhilosophy literally means 'love of wisdom' from the Greek 'philo' and 'sofia'. It is now widely used to designate the pursuit of knowledge or wisdom about fundamental matters concerning life, death, meaning, reality, being and truth. The term may also re questions: "What is choice? and "What is freewill?" People who view themselves as addicted to a substance, whether it's heroinHeroin or diamorphine ( INN) (colloquially referred to as junk, babania, horse, brown, smack, black tar, big H, lady H, dope, skag, juice, etc is an alkaloid opioid. Heroin is the 3,6- diacetyl derivative of morphine (hence diacetylmorphine and is synthes, alcoholIn general usage, alcohol (from Arabic al-khwl , or al-ghawl ) refers almost always to ethanol, also known as grain alcohol and often to any beverage that contains ethanol (see alcoholic beverage . This sense underlies the term alcoholism ( addiction to a or tobaccoacuminata N. alata N. attenuata N. bigelovil N. clevelandii N. debneyi N. excelsior N. exigua N. forgetiana N. glutinosa N. kawakamii N. knightiana N. langsdorffii N. longiflora N. obtusifolia N. otephora N. paniculata N. plumbagifolia N. quadrivalvis N., may believe themselves caught in the grip of uncontrollable physical urges, their freewill destroyed by altered brainFor other articles about other subjects named brain see brain (disambiguation). In the anatomy of animals, the brain or encephalon is the supervisory center of the nervous system. Although the brain is usually cited as the supervisory center of vertebrate chemistry. These users may be resistant to claims that they could stop using the substance if they wanted to, and that their perceived physical addiction may be little more than an illusionAn illusion is a distortion of a sensory perception. Each of the human senses can be deceived by illusions, but visual illusions are the most well known. Some illusions are subjective; different people may experience an illusion differently, or not at all.

Second, there would be serious social and economic implications for governments if they were to acknowledge that poor social conditions might alone be responsible for repeated drug misuse, rather than the addictive qualities of the drugs themselves. Instead of spending money on law enforcementlaw enforcement and the " and the " War on Drugs," governments of all political persuasions might be forced to consider diverting those funds, or increasing taxation, to improve living conditions for all citizens -- for example, by cleaning up the inner cities and pushing more money into education. Instead of prescribing methadone for a heroin user, a doctor might have to consider prescribing a decent home, paid for by government.

Third, the idea that some drugs, like heroin, create an almost instant neurophysiological addiction strengthens the hand of politicians who want the trade of these drugs to remain illegal, and of law enforcement authorities who demand special powers and funds to disrupt the black markets that evolve as a consequence.

For all these reasons, it could be argued that an inadvertent marriage of convenience has formed between drug users, law enforcement authorities and governments, each group with its own reason to promote the view that certain substances possess addictive qualities.

The drugs-are-addictive model affirms two claims:

Claim A: All or most people who use heroin or cocaine beyond a certain minimum amount become addicted.

Claim B: No matter what proportion of the users of heroin and cocaine become addicted, their addiction is caused by exposure to the drug.

Goldstein's views have not changed over the years. In a speech to the 1997 National Methadone Conference [1], he said: "Every addictive drug used by people is also self-administered by rats and monkeys. If we arrange matters so that when an animal presses a lever, it gets a shot of heroin into a vein, that animal will press the lever repeatedly, to the exclusion of other activities (food, sex, etc.); it will become a heroin addict. A rat addicted to heroin is not rebelling against society, is not a victim of socioeconomic circumstances, is not a product of a dysfunctional family, and is not a criminal. The rat's behavior is simply controlled by the action of heroin (actually morphine, to which heroin is converted in the body) on its brain."

Professor Alexander and his colleagues Robert Coambs and Patricia Hadaway at Simon Fraser University decided to test these claims by looking at the addictive powers of morphine hydrochloride.

The problem with normal animal studies, as Alexander's team saw it, is that the lab rats are highly stressed animals kept in social isolation in cramped cages. Could any experiment on such stressed-out creatures produce valuable information about the effects of drugs?

In his paper The Myth of Drug-Inducted Addiction [2], presented in January 2001 to the Canadian Senate Special Committee on Illegal Drugs, Alexander writes that laboratory rats are gregarious and curious creatures. Their ancestors are wild Norway rats, who are intensely social, and hundreds of generations of laboratory breeding have left many of their social instincts intact.

In normal heroin or morphine experiments, Alexander writes, where it is invariably shown that laboratory rats, once introduced to the drug, will self-administer whenever they can, researcher use rats who are "raised in isolated metal cages and subjected to surgical implantations in the hands of an eager (but seldom skillful) graduate student, followed by being tethered in a self-injection apparatus." [3]

The results of these experiments do not show the rats became addicted, argues Alexander, but that "severely distressed animals, like severely distressed people, will relieve their distress pharmacologically if they can." [4]

Instead of miserable rats, Alexander decided to use happy rats. What would happy rats do with morphine?

To answer his question, Alexander built Rat Park, the most natural environment for laboratory rats he could devise.

Rat Park was a rat colony that was airy and spacious, about 200 times the square footage of a standard laboratory cage. It had a peaceful British Columbian forest scene painted on the plywood walls, complete with lakes and mountains. It was heated to just the right temperature. It contained aromatic cedar shavings for nesting, empty tins for burrowing; and bright balls and wheels for play. It provided companionship, with 16-20 rats of both sexes in residence at the same time. There was plenty of space for mating, and a special place for birthing. It was rat heaven.

In normal cages, the rats’ appetite for morphine was measured by fastening two drinking bottles on each cage, one bottle containing a morphine solution and the other plain water, both of which were weighed daily.

In Rat Park, Alexander built a short tunnel large enough to accommodate one rat at a time. At the far end of the tunnel, the rats could drink a fluid from either of two drop dispensers, which recorded how much each rat drank. One dispenser contained a morphine solution and the other plain tap water.

In some experiments, Alexander forced the rats to consume morphine for 57 days on end, giving them no liquid to drink except the morphine-laced solution, before he allowed them to choose the tap water. In other experiments, he made the morphine solution so sweet that no rat could resist trying it. But whatever he did to induce the rats to use the morphine, Alexander invariably found significantly less appetite for morphine among the Rat Park rats than in the rats housed in normal cages. In some experiments, the caged rats were consuming 20 times more morphine than the rats in Rat Park.

In an experiment called the Seduction, the researchers put 16 lab rats into Rat Park and kept 16 others in standard cages. Because plain morphine is bitter, and rats have a sweet tooth, the researchers gave both sets of rats morphine-laced water with sucrose added, just a little at first, with the sweetness increasing each day. Both rats also had plain tap water to choose from.

The results were startling. The caged rats took to the morphine instantly, even with virtually no sweetener. But no matter how sweet the morphine became, the rats in Rat Park resisted it. They would try it occasionally, and the females would try more often than the males, but invariably they showed a preference for the plain water. By the end of the experiment, the caged rats had consumed 16 times more morphine than the Rat Park rats. It was a statistically significant finding.

Even more significant was this: When the researchers added Nalaxone to the morphine-laced liquid, the Rat Park rats began to drink it. Nalaxone is a substance that negates the effects of opioids but it spared the sweet taste of the water. The Rat Park rats, it seemed, wanted the sweet water, so long as it did not disrupt their normal social behavior. The rats wanted to play, eat and mate, Alexander concluded, not be anesthetized.

"Nothing that we tried," Alexander wrote, "instilled a strong appetite for morphine or produced anything that looked like addiction in rats that were housed in a reasonably normal environment." [5]

The rats who were given continuous morphine before being allowed to choose the tap water, did show some signs of physical withdrawal when they stopped taking the morphine, but they were minor, according to Alexander. He told psychologist Lauren Slater in an interview: "Rats in Rat Park showed what looked to be some minor withdrawal signs, twitching, what have you, but there were none of the mythic seizures and sweats you so often hear about." Opening Skinner's Box: Great Psychological Experiments of the Twentieth Century

Alexander believes that Rat Park shows that animal self-administration studies provide no empirical support for the theory of drug-induced addiction.

"The intense appetite of isolated experimental animals for heroin and cocaine in self-injection experiments," he wrote, "tells us nothing about the responsiveness of normal animals and people to these drugs. Normal people can ignore heroin . . . even when it is plentiful in their environment, and they can use these drugs with little likelihood of addiction . . . Rats from "Rat Park" seem to be no less discriminating." [6]

Rat Park proves, he believes, that the "belief in drug-induced addiction, at least with respect to heroin and cocaine, has no status as empirical science, although it has not been disproven. It is believed for some reason other than its empirical support." [7] Chemicals do not cause addiction, he argues, in the way that the measles virus causes a rash of red spots.

He told Lauren Slater: "I think withdrawal, like drugs themselves, is consistently overplayed; it's part of the narrative people have heard about drugs, and so continue to tell; it's the paradigm by which drug users may interpret what may be in fact only discomfort, not agony. Certainly the rats did not appear to be in agony." [8]

But the experiment, with its seemingly compelling conclusion, led nowhere and is largely forgotten. The two major biology journals Science and Nature rejected Alexander's paper. It was eventually published in Pharamacology, Biochemistry and Behavior, a respectable but much smaller publication, which is not widely read. Because of the paper's lukewarm reception, Simon Fraser University withdrew Rat Park's funding.

Just as Alexander's psychosocial study has all but disappeared, the strict biological reductionist models, like Professor Goldstein's, continue to gain strength.

In the meantime, according to Drug Sense, the U.S. federal, state and local governments spent $40 billion dollars in 2003 on the War on Drugs, a rate of about $1200 per second.