Hmm, I might have to read this book, since this subject is so interesting.
Lehrer's description of the amazing ability of dopamine to "predict" upcoming events is gripping all the way along, but I was delighted to learn that neuroscientists call signals for missed predictions (that is, the signal released when dopamine is released in anticipation of a reward that doesn't come), emanating from the anterior cingulate cortex the "Oh shit" circuit. The ACC is closely wired to the thalamus, so activation of the "Oh shit" circuit galvanizes the conscious mind, bringing the stimulus right to the front of our attention. [...]
Dopamine is the neurochemical star of the book, and its many pathologies make for gripping reading. There's a case study of Ann Klinestiver, a sedate school-teacher who was given strong doses of Requip a dopamine agonist (it imitates dopamine's action in the brain), as treatment for worsening Parkinson's Disease. Like 13 percent of Requip patients, Ann developed a gambling compulsion for slot machines that eventually ruined her life, costing her her husband, her family, and all her assets (she finally went off Requip and opted for severely constrained movement but no gambling).
The pathology here is all about missed predictions. Dopamine helps the brain to find patterns and thus make predictions about the future. But slots are random, and so in a normal brain, slot-play follows a common pattern: first the brain is delighted by the chance to chew on such a meaty problem. It formulates hypotheses about the slots' action, and then new input (mistakes that light up the Oh shit circuit) cause it to start over. But after a short time, a normal brain gives up -- there is no pattern to see, so there's no point in playing on.
But in a brain where the dopamine levels are abnormal, surrender never happens. The brain is in a constant state of reward, because of all the "new input" (random noise) that arrives every time the lever is pulled.
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