Human learning altered by electrical stimulation of dopamine neurons

This is a group of neurons. Credit: EPFL/Human Brain Project

Stimulation of a certain population of neurons within the brain can alter the learning process, according to a team of neuroscientists and neurosurgeons at the University of Pennsylvania. A report in the Journal of Neuroscience describes for the first time that human learning can be modified by stimulation of dopamine-containing neurons in a deep brain structure known as the substantia nigra. Researchers suggest that the stimulation may have altered learning by biasing individuals to repeat physical actions that resulted in reward.

"Stimulating the substantia nigra as participants received a led them to repeat the action that preceded the reward, suggesting that this brain region plays an important role in modulating action-based associative learning," said co-senior author Michael Kahana, PhD, professor of Psychology in Penn's School of Arts and Sciences.

Eleven were all undergoing (DBS) treatment for Parkinson's disease. During an awake portion of the procedure, participants played a computer game where they chose between pairs of objects that carried different reward rates (like choosing between rigged slot machines in a casino). The objects were displayed on a computer screen and participants made selections by pressing buttons on hand-held controllers. When they got a reward, they were shown a green screen and heard a sound of a cash register (as they might in a casino). Participants were not told which objects were more likely to yield reward, but that their task was to figure out which ones were "good" options based on trial and error.

When stimulation was provided in the following reward, participants tended to repeat the button press that resulted in a reward. This was the case even when the rewarded object was no longer associated with that button press, resulting in poorer performance on the game when stimulation was given (48 percent accuracy), compared to when stimulation was not given (67 percent).

"While we've suspected, based on previous studies in animal models, that these dopaminergic neurons in the substainia nigra - play an important role in reward learning, this is the first study to demonstrate in humans that near these neurons can modify the ," said the study's co-senior author Gordon Baltuch, MD, PhD, professor of Neurosurgery in the Perelman School of Medicine at the University of Pennsylvania. "This result also has possible clinical implications through modulating pathological reward-based learning, for conditions such as substance abuse or problem gambling, or enhancing the rehabilitation process in patients with neurological deficits."

Related Stories

Study implicates dopamine in food restriction, drug abuse

date Aug 20, 2013

Scientists today reported a possible basis for why food-restricted animals show increased susceptibility to drugs of abuse. This association has puzzled researchers since it was first observed more than three decades ago.

Recommended for you

Diet rich in methionine may promote memory loss

date 15 hours ago

Memory loss has recently been associated with excessive silencing of genes through a process called methylation. Researchers at the University of Louisville investigated the effects of a diet rich in methionine—an amino ...

Intelligent neuroprostheses mimic natural motor control

date Mar 30, 2015

Neuroscientists are taking inspiration from natural motor control to design new prosthetic devices that can better replace limb function. In new work, researchers have tested a range of brain-controlled devices ...

Researchers create 'Wikipedia' for neurons

date Mar 30, 2015

The decades worth of data that has been collected about the billions of neurons in the brain is astounding. To help scientists make sense of this "brain big data," researchers at Carnegie Mellon University ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.