By Douglas Quenqua | The New York Times | August 4, 2014
A tiny part of the brain keeps track of painful experiences and helps determine how we will react to them in the future, scientists say. The findings could be a boon to depression treatments.
The habenula (pronounced ha-BEN-you-la), a part of the brain less than half the size of a pea, has been shown in animal studies to activate during painful or unpleasant episodes.
Using M.R.I.s to produce powerful brain scans, researchers at University College London tracked the habenulas in subjects who were hooked up to electric shock machines. The subjects were presented with a series of photographs, some of which were followed by increasingly strong shocks. Soon, when the subjects were shown pictures associated with shocks, their habenulas would light up.
“The habenula seems to track the associations with electric shocks becoming stronger and stronger,” said Jonathan Roiser, a neuroscientist at the college and an author of the study, published in The Proceedings of the National Academy of Sciences.
The habenula appeared to have an effect on motivation, too. The subjects had been asked to occasionally press a button, just to show they were awake. They were much slower to do so when their habenula was active. In fact, the more slowly they responded, the more reliably their habenulas tracked associations with shocks.
In animals, the habenula has been shown to suppress production of dopamine, a chemical that drives motivation. Perhaps, the researchers say, an overactive habenula can cause the feelings of impending doom and low motivation common in people with depression.