Neural mechanism of learning process unveiled

Posted By: Staff
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Washington, July 30 (ANI): Scientists have revealed how a neural mechanism can provide real time snapshot of the learning process in humans.

The researchers have described a neural mechanism that allows reward signals to be combined over time to drive successful learning.

They claimed that the lateral prefrontal cortex (PFC) and the basal ganglia (BG) have been shown to play a key role in flexible association learning.

"We have known for some time that neurons in both areas care about response outcome-when we tell the animals whether they were correct or wrong, those neurons fire strongly. But we found that those responses can be maintained for a long time.

In order to learn, you need to remember what you did before and whether that action was beneficial or not. These neurons carry that sort of memory," explained lead study author Dr. Mark H. Histed from the Department of Neurobiology at Harvard Medical School.

The researchers studied the responses of neurons in the PFC and BG as animals performed a learning task where they were rewarded for making a correct association between a visual stimulus and an eye movement response.

And it was found that the activity of many of the neurons reflected the delivery (correct response) or withholding (incorrect response) of a reward and that this activity lasted for several seconds, the entire period between trials.

The researchers also observed that the outcome of a single trial impacted the neural representation of the learned association.

Specifically, they found that the response selectivity was stronger on a given trial if the previous trial had been rewarded and weaker if the previous trial was incorrect and therefore did not earn a reward.

"In other words, only after successes, not failures, did brain processing and the monkeys' behavior improve", said a co-author of the study.

The results show that cells in the PFC and BG not only exhibit robust and persistent signals about the outcome of behavioural responses, but that their selectivity is modulated based on trial outcome, demonstrating how behavioural outcome signals can shape learning.

"Our observations may represent a snapshot of the leaning process-how single cells change their responses in real time as a result of information about what is the right action and what is the wrong one," concluded the authors.

The study has been published in the recent issue of the journal Neuron. (ANI)

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