Investigators will perform fMRI analyses of adults engaged in reward-motivated memory tasks to test the hypothesis that learning can be facilitated by activation of the brain’s dopamine-producing nerve cells.
The ease with which people learn new information or behaviors depends greatly on their motivation. This phenomenon is often observed in psychotherapy; the patient has to be “ready” to take a life lesson to heart and change future behavior. The impact of motivation on learning can also be demonstrated in a laboratory setting, for example, by telling study participants that they will receive money if they are able to memorize a particular image. Using simulations of this kind, Duke researchers obtained evidence that the connection between motivation and learning involves specific groups of neurons in the midbrain that secrete the neurotransmitter dopamine. These so-called “dopaminergic” neurons become active when an individual is expecting a reward and are capable of stimulating brain structures involved in memory formation (the hippocampus, striatum, prefrontal cortex).
So far, though, the evidence that dopaminergic neurons stimulate memory formation has been largely circumstantial. Now, the investigators will use real-time fMRI monitoring of brain activity to test this hypothesis more directly. They will monitor changes in dopaminergic neuron activity that occur spontaneously over time and see if periods of increased activity are accompanied by improved performance on a memory test. In a parallel set of experiments, they will study groups of participants who have higher or lower levels of brain dopamine due to different forms of genes involved in dopamine transmission and determine whether specific gene forms are correlated with patterns of midbrain dopaminergic neuron activity and memory performance. All studies will use 40 genetically pre-screened healthy adults.
Significance: These studies may lead to identifying the causes of, and potential treatments for, disorders that are associated with impaired learning.