Brain's 'Eureka!' Circuit Found

The scientists presented two rhesus monkeys with a choice of four targets on a computer touch screen. The animals spent time exploring which target would trigger a juice reward by trial and error. Once the monkeys found the right target, the researchers then gave the monkeys a few seconds, during which they could repeatedly touch the rewarding target, exploiting their discovery to get more juice.

The experiments mimicked nature, where an animal might search "which hole is hiding food, and then go back to that hole if it proved to be a good source," said researcher Emmanuel Procyk, a neuroscientist at the University of Lyon in France.

During the experiments, Procyk and his colleagues recorded the electrical activity of hundreds of neurons in the anterior cingulate cortex. This brain region helps assess the rewards and costs of an action.

The anterior cingulate was more active when the monkeys were searching for the rewarding target, the researchers found. They also discovered certain neurons in this region specialized in firing just after the reward was discovered. These "eureka circuits" let the animals know when to stop exploring and start exploiting their discoveries.

Procyk noted this circuit's role in decision-making could malfunction in drug addiction or with the disorganized brain activity "in several mental disorders like schizophrenia."

Procyk and his colleagues detailed their findings in the Jan. 24 issue of the journal Neuron.

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