Control Your Vagus Nerve to Improve Mood, Alertness & Neuroplasticity

Andrew Huberman introduces the vagus nerve as a crucial connection between the brain and the body, transmitting a wealth of sensory and motor information.

Vagus Nerve: Pathway Connecting Brain To Body, Transmitting Sensory and Motor Information

The vagus nerve, also known as cranial nerve 10, is an intricate network with far-reaching connections that extend from the brain to various bodily organs. Its unique configuration supports both sensory pathways, which carry information from the organs back to the brain, and motor pathways, which convey instructions from the brain to regulate organ functions.

Vagus Nerve's Unique Body-Wide Connections

The vagus nerve's vast presence in the body distinguishes it from other cranial nerves that primarily interact with the head and neck areas. Huberman explains that this nerve connects the brain with the head, neck, chest, abdomen, and even the lower intestines. It is wired to have a precise impact on the body's organs and functions, such as the spleen, lungs, pancreas, and liver.

Vagus Nerve Neurons Are Bipolar, With one Axon for Sensory Input to the Brainstem and Another for Motor Commands From the Brain

More specifically, the neurons in the vagus nerve are bipolar, and unlike typical neurons often depicted in images, these have a peculiar shape. Each neuron's cell body is situated in the nodose ganglion, located near the neck and back of the head in the brainstem. Each neuron possesses two axons: one extending to a specific organ to receive sensory input and the other leading into the brainstem to carry out motor commands.

Vagus Nerve: Sensory Pathways For Chemical/Mechanical Info and Motor Pathways For Organ Function

The vagus nerve has a significant role in transmitting both sensory information, such as mechanical data from mechanoreceptors in the gut, and chemical information like acidity levels and serotonin concentrations, to the brain. The gut, for instance, is replete with mechanoreceptors that sense stretch and send this information to the brainstem through the vagus nerv ...

The importance of the vagus nerve in regulating various physiological and psychological states through autonomic balance and homeostasis is discussed, emphasizing the possibilities of both increasing alertness and enhancing relaxation.

Activating Vagal Pathways Can Affect Alertness, Relaxation, and Mood Regulation

Vagus Nerve: Part of Parasympathetic System, Increases Sympathetic Activity and Arousal

Electrical stimulation of the vagus nerve can increase the level of alertness in the brain. This works through a pathway from the Nucleus of the Solitary Tract (NTS) to the nucleus basalis, which stimulates the release of acetylcholine, enhancing alertness and focus. This type of stimulation is essential for adult neuroplasticity and can be activated naturally by high-intensity exercise. Sensory information collected by the vagus nerve's axons can modify the brain's levels of alertness and relaxation. However, the parasympathetic nervous system, which includes the vagus nerve, typically aims to put the body into a calm state. There is a conceptual misunderstanding that activating the vagus nerve always prompts relaxation; however, depending on which branch is activated, it can increase alertness. In fact, stimulating the vagus nerve can wake up the brain, enhance levels of motivation, alertness, and focus for various activities, and is even utilized to increase alertness during deep anesthesia.

Modulating Vagal Pathways Via Breathing and Activity Alters State

Activating certain branches of the vagus nerve can elevate or decrease alertness, influencing overall state. The motor outputs of the vagus nerve control organ functions, with particular branches influencing health, mental health, performance, and disease recovery. Auto-regulation ensures the balance between sympathetic and parasympathetic systems, facilitating controlled levels of alertness, heart rate, and breathing. Huberman indicates that activating the parasympathetic system by exhaling can shift from high sympathetic activation to lower levels, increasing calmness.

The sensory information carried by the vagus nerve includes both chemical and mechanical aspects, and changes in the vagus system's activity can be achieved through mechanical changes or alterations to the chemical milieu. To promote calmness, deliberate exhaling can slow heart rate, tilting the autonomic nervous system toward the parasympathetic side. Deliberate engagement of long exhales throughout the day can keep the pathway to the vagus nerve robust. Physical activities involving large muscles can stimulate vagal pathways, increasing motivation and reducing leth ...

Andrew Huberman delves into the role of the vagus nerve as a critical communication link in the gut-brain axis, particularly in relation to serotonin signaling—a key neurotransmitter relevant to mood, cognition, and gut health.

Vagus Nerve Relays Gut-brain Serotonin Levels

Huberman illuminates the dynamic where the gut cells produce most of the body's serotonin, which then affects brain regions through signaling relayed by the vagus nerve.

Gut Cells Produce Most of Body's Serotonin, Affecting Brain Regions

The gut is home to 90% of the body's serotonin, which is produced by enterochromaffin cells through an enzymatic reaction that transforms dietary tryptophan into serotonin. This serotonin, while not traveling to the brain, signals its presence to the brain via the vagus nerve, influencing the release of serotonin from the brain's dorsal raphe nucleus. Huberman states that serotonin plays a crucial role in mood regulation in the brain and is vital for gut motility and health.

Healthy Gut Microbiome and Dietary Tryptophan Regulate Serotonin Production

To ensure adequate serotonin production and overall gut health, Huberman highlights the importance of having a healthy and diverse gut microbiota, maintained by consuming low sugar fermented foods and a diet rich in tryptophan, from sources such as dairy products and white turkey meat. He indicates that the short chain fatty acids produced by the gut microbiota are involved in the biochemical pathway that converts tryptophan into serotonin, thus reinforcing the significance of gut microbiota and dietary input in maintaining serotonin levels.

Vagus Nerve Modulation of Gut Serotonin Affects Mood, Cognition, Neuroplasticity

The vagus nerve's involvement extends to the modulation of gut serotonin, which impacts the brain's serotonin production and, as a consequence, affects mood and wellbeing. Elevating serotonin levels in the brain through this gut-to-brain signaling can increase neuroplasticity, allowing people, including those with depression, to form new, positive perspectives on life. Huberman explains that serotonin binds to the terminals of vagus nerve neurons innervating the gut, with the signal then relayed up to the nucleus tractus solitaris ...

Andrew Huberman provides actionable tools that can affect the vagus nerve to alter arousal states, mood, and learning ability, without the use of pharmacology.

Exercises Activate Vagal Pathways For Physiological and Psychological Effects

Respiratory Maneuvers Engage the Vagus Nerve's Heart Rate Deceleration Pathway, Promoting Relaxation

Huberman discusses how the relationship between heart rate and breathing is coordinated by the vagus nerve, with inhaling accelerating and exhaling decelerating the heart rate. This deceleration pathway can be consciously engaged to promote relaxation. Techniques like the "physiological sigh," which consists of two inhales through the nose followed by a long exhale through the mouth, activate the parasympathetic nervous system through the vagus nerve. Extending exhales throughout the day strengthens pathways to the heart's sinoatrial node, with minimal effort, enhancing heart rate variability.

Neck Movements That Stimulate Vagal Afferents Activate Parasympathetic Pathways to Induce Calming Effects

Huberman suggests neck exercises to stimulate the vagus nerve. One example involves sitting with hands palm down, elbows at the table's edge, pushing down with the elbows while turning the head up to the right and left. This mechanical activation engages fibers of the vagus nerve, producing calming parasympathetic effects. He emphasizes that most of the ...