May 23, 2014 by Alexandra Jones
Drexel graduate student Amrit Misra recently took part in research with graduate students at the University of Pennsylvania, “Microstimulation of the Human Substantia Nigra Alters Reinforcement Learning,” which was published May 14. The research concluded providing electrical rewards to a certain set of neurons in the brain could alter the process of human learning.
Misra is currently working on a graduate degree in neuroscience at Drexel and is a doctorate of medicine and of philosophy candidate. He was recruited to help complete this project at Penn because of his expertise with specific neuron signaling.
“What they wanted to do was see if that stimulation that was delivered assisted people in their ability to recall things that they’ve learned,” Misra explained.
In this study, 11 patients undergoing deep brain stimulation surgery for Parkinson’s disease treatment completed question and answer tasks.
When the patients were awake, they played a computerized reward game using a handheld controller where they chose between objects with distinct correct and incorrect answers.
“Half the time they were left to do the task on their own and the other half they were given positive feedback in the form of electrical stimulation during the encoding or remembering stage of the trial,” Misra said.
If their responses were correct, the researchers would send microstimulations to the dopaminergic cells in the substantia nigra region of the brain using the electrodes that had been planted in their brains for the treatment.
“If you change the expectation so that the reward is not delivered when it is expected, there is a discrepancy. That discrepancy is thought to be encoded in the dopaminergic neuron population of the midbrain,” Misra said.
This discrepancy that occurs when there is no electric impulse sent to the dopaminergic neurons was linked to the patients forgetting the correct answers more frequently.
“So they thought, ‘If this discrepancy is really what’s mediating the learning and impacting people’s ability to remember something, then stimulation of that region specifically when they gave a correct response should have a better likelihood of learning the path [quickly],’” Misra further explained.
The results indeed found that electrical stimulation when a patient got a correct answer increased the patient’s ability to learn the correct response. It is the first study to show that electrical stimulation near the neurons can alter the learning process of humans.
“I kind of gave them the confirmation that that yes, there is a substantia nigra and here is proof that they’re modifying dopaminergic neurons because here are the dopaminergic neurons that they’re modifying,” Misra said.
Misra hinted that this kind of research could eventually lead to a breakthrough in student learning.
“I could imagine a device where you have a long-term implanted electrode in this region which is connected to a battery and allows its communicator to interact with some educational software,” Misra said.
Misra went on to describe a hypothetical process that could make student learning much more efficient.
“In the process of doing a homework assignment, if you answer correctly, you get positive reward stimulation which helps [you] remember those correct answers. If [you]’re remembering incorrectly, there is no stimulation and so you’re more likely to forget the incorrect answers,” he said.
According to Misra, the next step in the research process will be finding out how the dopaminergic cells are assisting in memory formation.
“All this says is that it is assisting in memory formation. The mechanisms of how would be the next area to kind of explore,” he said.