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Monday, April 11, 2016

Insights Into Addiction

"Some are very sensitive to losing, and if they take a risky option and lose, they're very likely to not go back to it again."
"That's very common in human behaviour. An analogy is a slot machine in Vegas."
Paul Phillips, professor of psychiatry and pharmacology, University of Washington

"[Human brains are more complex'] are not only affected by immediate recent losses [but] your appetite for risk in many circumstances might be at least possibly reducible to what a particular set of cells in a particular brain area is doing."
"[Finding the roots of risk in the brain] helps us understand what might be making people different in terms of their risk appetites. It may help us see them differently, maybe in a more tolerant way, to realize that there's a real biological basis for their behaviour."
Dr. Karl Deisseroth, neuro-scientist, Stanford University

"It seemed, at the time, like a stupid thing to do, because it didn't seem like adding lights and sound would have much of an impact. But when we ran the study, the effect was enormous."
"This particular drug has shown a lot of promise as a potential treatment for addictions."
Dr. Catharine Winstanley, associate professor, Department of Psychology, University of British Columbia

There is an assumption of free will in the choices that people make. From deciding -- perhaps on the spur of the moment, perhaps goaded by someone else, perhaps looking for release of some kind -- to experiment with a substance they have sought introduction to. Tobacco, for example, recreational drugs, or alcohol. Addiction to all three substances ruins lives. Their uninhibited use leads to social problems since they are, in essence, substances which if not used in moderation make the user anti-social.

Equally if not worse, is their adverse effect on health. In one instance addiction can be viewed as self-ostracization from societal norms, placing oneself eventually in a situation of non-functionality leading to the breakup of marriages, homes, families, and homelessness. Another type of addiction which occasionally goes hand-in-glove with any of the previous three is the attraction to gambling. Innocent enough when done as an occasional amusement, deadly when the urge becomes overpowering.

Scientists would like to more fully understand what motivates people to engage in risky and self-destructive behaviour. To be able, within the medical community, to engage with people needing help weaning themselves away from addictions, and using techniques to aid in that help that will succeed in steering people in a better direction. With the use of animal models research occasionally finds answers to the dilemmas that vex scientists' understanding.

Dr. Karl Deisseroth and his colleagues embarked on a research project and study hoping to better understand why some people are so vulnerable to self-harm addiction, and others are capable of avoiding them. The conclusion of their study led to the realization that a type of neuron or nerve cell in a particular region of the brain steers people away from risky choices. With the use of laboratory rats, researchers found a risk-averse rat made decisions based on the success of previous choices (food).

If they had pursued a direction that rewarded them with food, this would prompt them to repeat what they had done so successfully and conversely had a direction or action deprived them of food, it would be abandoned. Signals from receptors in a brain region called the nucleus accumbens were seen to be at play here, part of the system regulating dopamine, the neurochemical involved in emotion, movement and thinking.

Whereas in risk-taking rats these receptors emitted a fainter signal, resulting in those rats continuing to make faulty choices. The scientists found that by devising a technique using light to manipulate neurons, called optogenetics, brain cells were stimulated to heighten the "loss" signal, succeeding in turning risk-inclined rats toward a safer trajectory. Evidence was built that neurons with a dopamine receptor named D2 in the nucleus accumbens, integral to brain-reward circuitry, perform a role critical in the risky-or-not decision-making.

Insights gained from turning rats into problem gamblers may one day help humans with gambling addictions.
Insights gained from turning rats into problem gamblers may one day help humans with gambling addictions. (UBC)

Leading to the discovery by researchers that they could alter the neuron messages. When rats were offered a choice of two levers, one released a consistent amount of sucrose while the other delivered a tiny amount, yet on occasion a flood of sucrose would result in 25 percent of presses on the negative lever. Risky rats gambled on the lever that occasionally gushed sucrose but more commonly gave tiny spurts, while the risk-averse rats remained influenced by their last choice which, if the risky lever was selected and a trickle emerged, the consistent lever was selected next time around.

With the use of optogenetics, the research team stimulated nucleus accumbens neurons with D2 receptors just at the time of the food-lever decision presented to the laboratory rats. The receptors responded by sending strong loss signals to the rats, encouraging them to play it safe with their next lever choice if their experience had been disappointing with the initial one. Which has led Trevor Robins, chairman of the psychology department at the University of Cambridge to feel that the study might produce insights for drug addiction.

The study "clearly involves the dopamine system and those areas of the brain", and for addicts the same receptors produce weaker signals. And while optogenetic manipulation is considered too invasive for use in humans, findings from those animal studies are now being utilized in the identification of brain areas to be targeted with non-invasive brain stimulation to succeed in confronting problems such as cocaine addiction.

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