Neuroscientists have traced feelings of anxiety to a specific group of brain cells, which they have imaginatively named “anxiety cells”. Even more excitingly, the team has discovered how to control these worry-inducing neurons and, by doing so, reduce the symptoms of anxiety. Their findings have been published in the journal Neuron.
The researchers used a technique called calcium imaging on mice. This involves inserting miniature microscopes into the mice's brains and recording cell activity in the hippocampus as they go about their day-to-day business.
When the critters were stressed – in this case, because they entered an exposed area, which (theoretically) left them vulnerable to predators – the researchers observed high levels of activity in the ventral part of the hippocampus. The more anxious the mouse, the more active the neurons.
These "anxiety cells" probably exist in humans too, Rene Hen, a professor of psychiatry at Columbia University Irving Medical Center (CUIMC), said in a statement.
But the researchers didn't just identify the cells – they figured out a way to control them. The team used optogenetics, a process that involves beams of light, to turn the anxiety cells "off". When in this state, the mice acted less fearful. They became bolder and increasingly veered away from the walls and into the open spaces. When the cells were stimulated, however, the researchers observed the opposite reaction. The mice were fearful of even the "safe" areas, i.e. beside the walls.
A certain amount of anxiety is a good thing. It might push you to study a little harder for a test or run away from an oncoming car or, as may have been the case for our prehistoric ancestors, a saber-toothed cat.
Too much, however, can be disruptive, not to mention extremely unpleasant for the person involved. Today, anxiety is the world's most common mental illness, affecting 18.1 percent of Americans in any given year. Those with the disorder overestimate potential threats – it’s no longer a predator causing your anxiety to flare but a crowded train carriage or a tight deadline.
But findings here add to the growing body of research into the cause of anxiety and offer new hope for those suffering from the disorder.
"Now that we've found these cells in the hippocampus, it opens up new areas for exploring treatment ideas that we didn't know existed before," said Jessica Jimenez, lead author and MD/PhD student at Columbia University's Vagelos College of Physicians and Surgeons.