A new study on the neurological basis of anxiety has identified cells in the hippocampus that appear to regulate anxious behavior.
The results, so far demonstrated in experiments with laboratory mice, offers a glimmer of hope to millions of people around the world who suffer from anxiety disorders. They are paving the way for new drugs to control neurons. “We wanted to understand where the emotional information translated into the feeling of anxiety is encoded in the brain,” says neuroscientist Mazen Kheirbek of the University of California at San Francisco.
To find out, the team relied on a technique called “calcium imaging”. This method was used to record the activity of hippocampus cells in mice, using miniature sensors previously inserted into their brains. The data was collected while the animals were moving in special labyrinths made for the experiment. Inside were some paths leading to open spaces and high platforms, exposed environments known to cause anxiousness in mice, due to increased vulnerability to the predators they bring.
Far from the security of the walls, something happened in the heads of the mice. Observing a group of cells in a part of the hippocampus called ventral CA1, the researchers noticed that the more the mice were anxious, the greater the neuronal activity became in this region. “These cells only work when the animals are in places that scare them,” says René Hen, co-author of the study. They have also been localized in the hippocampus region, which – among other things – regulates the hormones that control emotions.
Because this same regulation process also works in humans, researchers assume that these “neural neurons” could also be part of our system. “Now that we have found these cells in the hippocampus, it opens up new perspectives for exploring therapeutic ideas that we did not know existed,” says Jessica Jimenez of Vagelos College of Physicians & Surgeons at Columbia University.
In addition, researchers have already found a way to control these “anxiety cells” — at least in mice. Using a technique called optogenetics to shine a beam of light onto the cells, the researchers were able to silence them and stimulate more “confidence” activity in the mice. “What we discovered was that they became less anxious, they even tended to explore the rest of the labyrinth more specifically.”
Finally, by modifying the light parameters, the researchers have also succeeded in doing the opposite: boosting the activity of anxious cells, even to the point of shaking the animals even though they were safely installed in a confined and closed environment. The next steps will be to determine if this same control switch regulates human anxiety.