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Pleasure and pain
Sub-Topics
Pleasure-Seeking Behaviour
Pleasure and Drugs
Avoiding Pain

Linked
Help Projections from VTA and to VTA Crossing the Line to Addiction: How and When Does It Happen? Relapse and Craving
Can the Addicted Brain Change Back? The Reward Map
Experiment
PET Neuroimaging Reveals How Cocaine Addiction Develops

Dependencies are attributable not solely to the pharmacological effects of the drugs in question, but also to their interaction with each individual’s particular neurobiological constitution. This constitution varies as a result first, of the individual’s genetic inheritance, and second, of his or her environmental influences and experiences. Such issues push the limits of animal models, but animal models are nevertheless an essential prerequisite for any neurobiological analysis of human behaviour.
THE PLEASURE CENTRES AFFECTED BY DRUGS

Among the various brain structures classified under the heading of the “reward system,” the following three seem to play the most decisive roles: the ventral tegmental area (area A10), which is located in the midbrain and contains the dopaminergic neurons that innervate the limbic system and the prefrontal cortex; the nucleus accumbens or ventral striatum, which is located in the septal region, innervated by the ventral tegmental area, and serves as an interface between the limbic system and the motor system; and the prefrontal cortex, whose role in the processes of attention and motivation is well established.

Many other structures in the brain are affected by the use of psychoactive substances. Most of the neuroanatomical studies in which these structures were identified were performed on rats. But because the major anatomical divisions and biochemistry of all mammal’s brains are similar, the areas of the rat’s brain that react to certain drugs can reasonably be transposed to the human brain as well.

  To see what parts of the brain can be affected by each of the drugs listed below, click on each one’s name in turn, and note the changing patterns in the illustration to the left. As these patterns indicate, the ventral tegmental area and the nucleus accumbens are affected by all of these drugs.



Cocaine and Amphetamines

Opiates

Alcohol

Cannabis

Nicotine

 
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