The Brain-Body Connection and the Vagus Nerve

Source: BGStock72/Shutterstock

Interoception and emotions

Communication between the body and the nervous system is called interoception and it allows the brain to sense internal states, such as hunger, pain, or heart rate. The vagus nerve is an important part of interoception that can have a profound effect on how we are feeling, even influencing emotions such as anxiety and depression. Although the link between interoception and emotion is known, it is unclear how the vagus nerve changes due to stress. A recent study by Okonogi and colleagues delved into this topic using powerful methods in laboratory mice. (2024)

The vagus nerve is changed by stress and anxiety

To better understand how the vagus nerve is changed by stress and anxiety, the authors of the study exposed mice to a form of psychosocial stress called social defeat. In social defeat, a mouse is repeatedly exposed to a more aggressive mouse, which increases stress in a way like what would be experienced during bullying. Some mice are resilient to this form of social stress and their social and exploratory behavior does not change. However, other mice are susceptible and develop strong social avoidance. Using specialized equipment, the authors were able to monitor electrical activity in the vagus nerve in mice exposed to social defeat stress. They found that vagus activity was decreased in stress-susceptible mice compared to stress-resilient mice. This suggests that interoceptive communication is altered by stressful experiences in stress-susceptible mice.

Vagus nerve activity and the brain

The prefrontal cortex and the amygdala are important brain areas associated with the control of anxiety. The authors recorded brain waves in the prefrontal cortex and amygdala in non-stressed, stress-resilient, and stress-susceptible mice and they found that certain brain waves were different in stress-susceptible mice. Interestingly, when the vagus nerve was stimulated repeatedly, these brain waves returned to non-stressed, or stress-resilient levels.

Potential uses of vagal nerve stimulation

Vagus nerve stimulation is currently being used to help individuals suffering from treatment-resistant depression, which is severe depression that does not get better with therapy or antidepressant medications. The findings of the above study offer promising insights into the potential of vagus nerve stimulation as a therapeutic approach for anxiety and depression. By targeting this crucial nerve and restoring disrupted brain wave patterns, researchers may be able to develop new and more effective treatments for these debilitating conditions.

As individuals, we can also work to improve our own interoceptive awareness. Mindfulness practices, meditation, and deep breathing exercises can help us tune into our bodies' signals and reduce stress. By strengthening our mind-body connection, we may be able to better manage our emotions and improve our overall well-being.