How the Brain Makes the Right Decision ?

Making the right decision under difficult or emergency situation is a very important and complex process in the brain, still little understood by neuroscientists. The question is how the brain is able to signal the best course of action, given a number of possible behaviors, by using sensory information. Experimental research with monkeys which has recently been published in the journal Science now seems to imply that a neurotransmitter (substances that are secreted by nerve cell endings and which are used for communication between cells) called dopamine has a key role in the brain decision making processes. Researchers from Texas, USA and Fribourg, Switzerland, have determined this by implanting small electrodes (metallic wires used to record the electrical activity of neurons) in the brains of monkeys. The animals were trained to press a level in response to a visual pattern presented to them, in order to receive a reward of fruit juice. In this way, the scientists could measure the rate of electrical firing (reflecting the working of the dopamine-bearing neurons) when the amount of reward which was expected by the monkey was increased or decreased. The results of these experiments have shown that the dopamine neurons will increase their firing when the reward is higher than expected, and decreases it when the reward is less than expected. "The way the neurons change their predictions correlates with the behavioral changes of the monkey almost exactly", said one of the researchers, Dr. Montague.

SOURCE: Science (1997: 275:1593-1598)