Here's how our brain processes emotions

A team of neuroscientists has identified the circuits that could play a role in mental illnesses, including depression.

Some mental illnesses may stem, in part, from the brain's inability to correctly assign emotional associations to events. For example, people who are depressed often do not feel happy even when experiencing something that they normally enjoy.

The study from MIT reveals how two populations of neurons in the brain contribute to this process. The researchers found that these neurons, located in an almond-sized region known as the amygdala, form parallel channels that carry information about pleasant or unpleasant events.

Learning more about how this information is routed and misrouted could shed light on mental illnesses including depression, addiction, anxiety, and posttraumatic stress disorder, said senior author Kay Tye.

"I think this project really cuts across specific categorizations of diseases and could be applicable to almost any mental illness," says Tye.

The findings suggest that to fully understand how the brain processes emotions, neuroscientists will have to delve deeper into more specific populations, Tye said.

"Five or 10 years ago, everything was all about specific brain regions. And then in the past four or five years there's been more focus on specific projections. And now, this study presents a window into the next era, when even specific projections are not specific enough. There's still heterogeneity even when you subdivide at this level," she added. "We've still got a long way to go in terms of appreciating the full complexities of the brain."

In the long term, the researchers hope their work will lead to new therapies for mental illnesses. "The first step is to define the circuits and then try to go in animal models of these pathologies and see how these circuits are functioning differently. Then we can try to develop strategies to restore them and try to translate that to human patients," says co-lead author Anna Beyeler.

The study appears in journal Neuron.