Learning

What is Learning?

Acquisition of new knowledge, behavior, skills, values, preferences or understanding

How does one learn? What goes on in the brain?

Positive and negative feedback

Learning from error When an error is made, EEG shows a dip in voltage (activity) –An error-related negativity (ERN) occurs about 100ms after muscle-based error –ERN ms after unfavorable feedback or monetary loss

The Medial Prefrontal Cortex The Role of the Medial Frontal Cortex in Cognitive in Cognitive control Minding Mistakes, Scientific American ERNs originate in medial pre-frontal cortex (anterior cingulate) as indicated by fMRI

Anterior Cingulate Cortex

Neurons in anterior cingulate fire in response to reduced reward or error In animals, neurons fire when subject decides to change behavior in response to error Blocking function of these neurons prevent animals from making changes in behavior in response to error In humans, if this region of the brain is removed, subjects have reduced ability to respond “correctly” to reduced reward (error) These neurons must be responsible for or at least involved in learning from error using negative feedback as a guide

Also, damage to the anterior cingulate results in animals that make immediate changes in response to error (rather than waiting for multiple errors before changing behavior) This suggests that this region is responsible for evaluating the short-term history of success or failure and using that as a guide for future action

Dopamine neurotransmitter and learning from error Anterior cingulate has dopaminergic neurons –Correct responses results in high levels of dopamine release (positive reinforcement by stimulation of the “Go pathway” and inhibition of the “NoGo” pathway) –Incorrect responses results in reduced dopamine release (negative reinforcement by suppressing the “Go” pathway and releasing the “NoGo” pathway from inhibition) Low dopamine levels resulting from error lead to avoidance behavior

Parkinson’s Disease and learning Parkinson’s Disease results from loss of dopamine producing neurons in the substantia nigra Parkinson’s patients learn best from negative feedback, and not so much from positive feedback

Mental relaxation occurs about 30 sec before making an error