Two separate groups of neurons in the brain's ancient visual center respond to threat and fear at different speeds.

Our brains must spot emotional faces quickly to keep us safe. Scientists think this speed comes from a subcortical pathway, a deep visual shortcut that runs from an area called the superior colliculus through the thalamus to the amygdala. However, the exact steps in this circuit have remained unclear. To learn how it works, researchers studied neurons in the superior colliculus to see how they handle facial expressions. They discovered two separate, largely nonoverlapping groups of neurons that react to these faces. One group responds very quickly, showing a short-latency preference for threatening faces. The other group shows a delayed preference for fearful faces. This shows the superior colliculus divides emotional tasks between distinct sets of cells.

Why it matters

This pinpoints where and when the brain first distinguishes threatening from fearful faces. For anyone studying anxiety, PTSD, or social disorders, knowing that threat and fear are processed by different neurons at different times could lead to more targeted treatments or therapies that intervene at the right moment.

Questions answered