Learning and Dopamine

A new study published in the 5 November 2004 issue of the journal Science helps explain a puzzling phenomenon seen in Parkinson's patients: dopamine levels worsen performance in some cognitive tasks despite improving performance in other tasks.

The study's findings show that Parkinson's patients who take a break from medications that increase dopamine levels learn better from negative feedback but worse from positive feedback than healthy people of the same age and IQ. When these same Parkinson's patients take their dopamine medication, they show the reverse pattern, learning better from positive feedback and worse from negative feedback than controls.

Dopamine is a brain chemical associated with feelings of pleasure and reward that is thought to contribute to learning through both positive and negative feedback. Loss of dopamine leads to the symptoms of Parkinson's.

This work may also extend beyond Parkinson's to address the neurobiology of learning from experience — learning that occurs when positive feedback or rewards reinforce behavior and negative feedback causes people to avoid such behavior.

4 November 2004