together we can change ourself

together we can change ourself

Archive for May 2007

A Neural Key to Learning

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The hippocampus, wrapped around a ventricle in the lower brain, holds one key to learning. This structure enables us to store for the longterm what’s in our “working memory,” the holding in mind of new information as our mind connects new information with what we already know. Once these connections have been made, we have learned — and will be able to bring the new understanding to mind weeks or years later. Whatever a student hears in class, reads, or observes, travels these pathways as he masters yet another iota of understanding. Indeed, everything that happens to us in life, all the details that we will remember, depend on the hippocampus to stay with us.

This continual retention of memories demands a frenzy of activity in the neurons of the hippocampus. The vast majority of neurogenesis – the brain’s production of new neurons and laying down of connections to others – takes place in the hippocampus, at a rather furious rate. Destroying the hippocampus ends our ability to learn; neurological patients with damage there live every moment as though the last had not occurred. Some conditions – notably trauma and depression — actually shrink the hippocampus by killing off cells. As patients recover from these disorders, their hippocampus gradually grows back, neuron by neuron.

In terms of learning, the most sinister impact on the hippocampus comes from ongoing emotional distress, which releases high levels of stress hormones like cortisol. If stress becomes perpetual, cortisol can actually attack the neurons of the hippocampus, slowing the rate at which neurons are added or even reducing the total number, and so impairing our very ability to learn and remember. The killing off of hippocampal neurons occurs at extreme levels, during sustained cortisol floods induced, for example, by severe depression or intense trauma.

Even at lower levels, extended periods of high levels of the stress hormone cortisol seems to hamper the growth of these same neurons. Cortisol stimulates the amygdala while it impairs the hippocampus – with a disastrous impact on learning. This neurological dynamic forces our attentional focus on the emotions we feel, while restricting our ability to take in new information, and so learn. Instead we imprint what is upsetting us. After a day when a student gets panicked by a pop quiz, he’ll remember the details of that panic far more than any of the material in the quiz.

That neurological fact has profound implications for the kind of classroom atmosphere that fosters learning. The social environment, remember, impacts the rate and fate of newly created brain cells. It takes a month for new cells to mature, and four more for them to fully link to other neurons; during this window the environment determines the final shape and function of the cell. The new cells that facilitate memory during the course of a semester will encode in their links what has been learned during that time – and the more conducive the atmosphere for learning, the better that encoding will be.

Written by Bhushan Kulkarni

May 29, 2007 at 12:18 pm