Heart palpitations, tremors or dizziness, sweating, difficulty concentrating … The physical symptoms of fear are well known. But until now, what happens in our brains when we feel fear has remained largely unknown. This is because the mechanisms involved lie deep in the brain, where brain wave readings are difficult to obtain. Thanks to a team of Chinese and German researchers, the mystery is about to go away. In a study published in science progressThey detail the results of their experiments, which were conducted with epilepsy patients who equipped them with brain sensors before they were subjected to a fear-learning task.

Activity is concentrated in the amygdala and medial prefrontal cortex

Previous work had already suggested that in the brain, fear originated in the amygdala and in the medial prefrontal cortex (MPC), which this new study confirms. To learn more about what happens in these areas of the brain, the researchers showed volunteers a box on a computer screen. At random times, a shock to the wrist was accompanied by the presentation of a colored square, to teach the volunteer to fear that square. Then the same volunteers looked at the square again after placing their tentacles.

The study authors were then able to see an increase in brain activity when a volunteer saw a box that they attached to a shock to the wrist – a measure of the fear response. This brain activity is a type of rhythm called a theta wave, which occurs in both the amygdala and the CPM.

The researchers also note that this fear response originated in the dorsal CPM, as it has previously been studied in primates. Scientists now hope that this work will lead to the development of treatments for anxiety disorders.