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Anti-anxiety circuit found in unlikely brain region

scary clown.jpg

A generally useful rule in hide-and-go-seek: Always hide where nobody will even think of looking for you.

The last place a neuroscientist would think of looking for a brain circuit with a calming function might be the amygdala, an almond-shaped structure embedded deep within the brain. The amygdala, after all, is considered the "seat of fear" in mammals: Excite it - zap it, say, with a carefully positioned electrode - and invariably the result is heightened anxiety. (Apparently this happens often enough in real life; more than one in four of us will, at some point in our existence, experience anxiety at levels high enough to qualify as a psychiatric disorder.)

But an electrode is a crude probe: It stimulates every nerve fiber in the neighborhood. When, on the other hand, Stanford brain scientist Karl Deisseroth, MD, PhD, and his labmates eschewed this sledgehammer approach and adopted another one pioneered by Deisseroth and endowed with pinpoint precision (it's called optogenetics), they managed to tease out a nerve circuit situated smack-dab in the amygdala that counters anxiety when stimulated.

Today's anti-anxiety drugs are inhibitors, intended to suppress impulses traveling through the vast preponderance of circuits in the amygdala that are anxiety-inducing rather than anxiety-relieving. These drugs aren't very effective. Moreover, they tend to be addictive and, because they can also suppress other things such as, for instance, breathing, they can be dangerous.

The newly identified brain circuit opens the door to new therapies for anxiety. Stimulatory drugs targeting it might be both effective and safer.

Clinical trials take a lot of time and money, so any actual pharmaceutical payoff is undoubtedly years away. But just knowing it's coming, I feel strangely calm already.

Previously: Nature Methods names optogenetics its "Method of the Year" and Using light to get muscles moving
Photo by scyllacat

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