Novel Brain Fear Mechanisms Discovered, Offers Target For Anxiety-Reducing Drugs; Study

Feeling nervous or anxious in a social situation is normal. Most of us are no strangers to shivery knees or cracky voices while giving a presentation and that feeling of butterflies in our stomach when meeting someone (no, it's not love - it's just nervousness).

While some anxiety symptoms are minor and manageable, the symptoms can be quite bothersome and disrupting for others. In addition, while there are many different anxiety medications available, most of them are not effective and have unwanted side effects [1].

In a recent study, researchers discovered a new target in the brain that underpins the eliciting of anxiety and fear behaviours such as 'freezing.'

Brain Fear Mechanisms And Anxiety

Researchers at the University of Bristol say their discovery of brain pathways could lead to a new drug target for treating anxiety and psychological disorders, which affect more than 264 million people worldwide. The findings will be published in the journal eLife [2].

The School of Physiology, Pharmacology and Neuroscience at the University of Bristol studied how the cerebellum, connected to numerous brain regions associated with survival networks, influences activity in the periaqueductal grey (PAG) region. The PAG area sits at the centre of a network that coordinates survival mechanisms, including fear-evoked responses such as 'freezing.'

Dr Charlotte Lawrenson and Dr Elena Paci, the lead authors of the study, said, "until now, little was understood about how the cerebellum modulates neuronal activity in other brain regions, especially those related to fear and anxiety. Importantly, our results show that the cerebellum is part of the brain's survival network that regulates fear memory processes at multiple timescales and in multiple ways, raising the possibility that dysfunctional interactions in the brain's cerebellar-survival network may underlie fear-related disorders and comorbidities" [3].

Why Are The Findings Important?

Anxiety-reducing drugs are not always effective for all patients and often have unwanted side effects. Studying the brain networks and mechanisms that underlie fear and anxiety may lead to better treatments for anxiety disorders [4].

Researchers recorded activity in the PAG region of animal models' brains using electrodes. The models receive an auditory tone paired with a small foot shock as part of the conditioning task. Consequently, this causes a 'fear memory' and freezing, which indicates fear.

During the encoding of fear memory, scientists found that a subset of brain cells in the brain's PAG area was too responsive to conditioned tones.

On A Final Note...

The study provides new insights into how the PAG encodes fear memory and also shows that the cerebellum is another key brain structure in the fear/anxiety network and offers new hope for treating psychological conditions such as post-traumatic stress disorder.