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Introducing Fear, Trauma & Trauma

  • In the Huberman lab podcast, Professor Andrew Huberman discusses the neuroscience of fear and trauma. He explains the biology of fear, how it is unlearned and how it can be replaced with a positive event.
  • He will also discuss a recent study that showed how five minutes a day of deliberate exposure to stress can alleviate longstanding depressive and fear related symptoms.
  • He will provide an overview of the biology of fear, the mechanisms of fear extinction, and practical tools to confront fear and trauma. He will also explain the importance of replacing fear with a positive event in order to effectively extinguish fear.

What is Fear?

  • Fear is an emotion that is hotly debated and includes both physiological and cognitive components. It involves quickening of the heart rate, changes in blood flow, and a narrowing of awareness.
  • Stress and anxiety are elements of fear, but can exist without it.
  • Trauma is a specific type of fear that gets embedded in the nervous system and is reactivated at times when it is maladaptive. Other terms related to fear include phobias and panic attacks.
  • By acknowledging the different types of fear, we can focus on the biological and cognitive processes that form them and how to replace fearful experiences with new memories.

Autonomic Arousal: “Alertness” vs. “Calmness”

  • The autonomic nervous system is a part of the nervous system that controls digestion, urination, sexual behavior, and stress.
  • It has two branches, the sympathetic and parasympathetic, which control alertness and calming respectively.
  • The sympathetic nervous system acts as the accelerator for alertness and attention, while the parasympathetic branch is the calming nervous system. This Seesaw adjusts our overall level of alertness, and it is important to understand in order to recognize and manage fear and trauma.

Hypothalamic-Pituitary-Adrenal Axis (HPA axis)

  • The HPA axis stands for hypothalamic pituitary, adrenal axis, which is a three-part system that uses the brain to alert and prepare the body for action. This system can trigger the release of hormones and chemicals that make the body alert and ready to go, both in the short and long term.
  • Fear responses that involve the HPA axis can be very brief, but the chemicals involved can have a long-lasting effect and can embed fear in the brain and body.
  • This slow and fast phase of the HPA axis and fear response is an adaptive response, and it can be leveraged to extinguish the fear response and replace it with non-fearful responses.

“The Threat Reflex”: Neural Circuits for Fear

  • The amygdala is an almond-shaped structure in the brain that is part of what is known as the threat reflex. It is responsible for generating a generic fear response that can be associated with any external experience. This response includes quickening of the heart rate, hypervigilance and increased access to energy stores.
  • The amygdala also forms part of the amygdala-Lloyd complex, which has 12-14 areas and takes in information from memories and the senses. It outputs to the hypothalamus, the adrenals and the periaqueductal gray to trigger the fight, flight or freeze responses.
  • It also sends signals to the locus cerilios to create arousal, and to the nucleus accumbens to activate the dopamine reward system. By understanding the neural circuits and biology of fear, we can start to reveal the logic of how to attack fear.

Controlling Fear: Top-Down Processing

  • The fourth component of fear is the ability to attach a meaning and purpose to the generic response of fear. This is accomplished through top-down processing, which is largely controlled by the prefrontal cortex.
  • An example of this could be overriding the reflex to pull away from a tack when stepping on it. Other reflexes like getting into cold water can also be overridden with top-down processing.
  • The narrative created by the prefrontal cortex can either lead to persisting, pausing, or retreating from the fear response.

Narratives: “Protective or Dangerous”

  • Fear is an adaptive response that helps protect us from dangerous situations, however, some memories that evoke fear can be maladaptive and limit our behavior.
  • Memories can be categorized as protective or dangerous, with protective memories helping us to avoid bad decisions and dangerous memories creating a sense of discomfort. Harvard professor Dr. Carrie Wrestler has done extensive research on fear, and has described it as containing a historical component.
  • He has also discussed the concept of memories being protective or dangerous in the context of fear. Lastly, certain memories become attached to the fear system, which activates the threat reflex in anticipation of what might happen.

Attaching Fear to Events: Classical Conditioning & Memory

  • Pavlovian conditioning is a type of learning in which an organism responds to a stimulus after it has been repeatedly paired with a second stimulus. This behavior was famously demonstrated in Pavlov's dogs, in which they salivated in response to ringing a bell after the bell had been repeatedly paired with food.
  • The unconditioned stimulus is the stimulus that naturally elicits a response, such as food or a loud noise.
  • The conditioned stimulus is the stimulus that is paired with the unconditioned stimulus. It is the conditioned stimulus that eventually creates the response, such as salivating in the case of Pavlov's dogs.
  • Fear systems work similarly, in that one intense experience can lead to a long-term fear response.
  • In addition, these fear responses can be based on one intense experience or an accumulation of experiences. Finally, the fear system is wired to be able to include memories of both acute and long-term experiences.

How Fear Learning Occurs: Long Term Potentiation, NMDA

  • Neuroplasticity is the nervous system's ability to change in response to experience, which is done through long-term potentiation and depression.
  • Long-term potentiation strengthens the connection sites between neurons and creates a more robust and faster communication between neurons, allowing us to create an association between an event and the fear response.
  • Long-term depression weakens the connection sites between neurons and creates a more difficult and slower communication between neurons, allowing us to extinguish a fear and unlearn an association. Brain-derived neurotropic factors and calcium entry also play a role in this process.

Extinguishing (Reducing) Fears

  • Fear and trauma can have long-lasting effects on an individual, and current treatments such as SSRIs and benzodiazepines may provide some relief from symptoms.
  • However, these treatments are not directly targeting the neurobiology of fear and trauma. To rewire our brains and eliminate fears and traumas, we need to both extinguish the fear and replace it with a positive experience.
  • This process involves weakening the connections between the person, place, or thing and the threat reflex and strengthening the positive experience. Therapies such as NMTA receptor modulation can help achieve this, allowing us to work through our fears and traumas.

Cognitive (Narrative) Therapies for Fear

  • The primary form of therapy used to rewire the nervous system in order to reduce fears and traumas is through language.
  • Prolonged exposure therapy, cognitive processing (CPT), and cognitive behavioral therapy (CBT) have been proven to be effective in this regard.
  • The process involves retelling the traumatic experience in detail, which activates the fear reflex, but with each successive retelling the amplitude of the physiological response decreases until it becomes a boring, bad story.
  • This is known as fear extinction. It can be done in a therapist's office, in a group setting, or through journaling, however a feeling of trust is essential.
  • Journaling can be effective, but caution should be taken when reactivating traumas without appropriate social support.

Repetition of Narrative, Overwriting Bad Experiences with Good

  • The formation of new, non-traumatic associations with an event or person is key to overcoming fear and trauma.
  • Diminishing the amplitude of the physiological response to the event is the first step in this process. After this, the individual must relearn a new narrative to replace the old one and form positive associations with it.
  • This is done by attaching a sense of reward to the traumatic event. Narrative is a powerful way to rewire the brain and form new relationships to past events. It is important to not forget the negative experiences, but to form a new perspective on them.

EMDR: Eye Movement Desensitization Reprocessing

  • Narratives should not be underestimated as a tool to rewire our nervous system. Prolonged exposure therapy, cognitive processing and cognitive behavioral therapy are all forms of therapy that can help to reduce fear and trauma.
  • Eye Movement Desensitization and Reprocessing (EMDR) involves moving the eyes side to side while recounting a traumatic or fearful narrative.
  • Studies have suggested that lateral eye movements can result in a dramatic reduction in the activation of the fear reflex circuitry and autonomic arousal.
  • EMDR has been shown to be most beneficial for single event traumas, not necessarily long-term traumas such as a bad marriage or childhood. EMDR practitioners are open to feedback in order to improve their practice and make it more effective.

Social Connection & Isolation Are Chemically Powerful

  • Trauma and fear can have a long lasting effect on the brain and to help reduce this, social connection is key. This is backed up by emerging neuroscience literature showing that Taki Kynan, a molecule found in the brain, is activated when a fearful or traumatic event happens.
  • Studies have shown that low to moderate levels of anxiety, aggression, and irritability are caused by increased Taki Kynan levels and that social connection can reduce this.
  • Social connection does not have to be physical contact, but could be conversation, sharing a meal, or physical touch if appropriate. Engaging in social connection outside of the trauma-related work is beneficial as it helps reduce the fear and trauma.

Trans-Generational Trauma

  • Trauma and fear can be passed on from one generation to the next, known as transgenerational passage of trauma.
  • Recent studies have proven that humans have the capacity to inherit a predisposition to trauma or fear from their parents or grandparents.
  • This predisposition is linked to the genetic code and results in a lower threshold to develop trauma or extreme fear to certain types of events. This isn't the same as the trauma experienced by the parent being passed on, but rather a predisposition of the threat reflex to be activated more easily.
  • Treatment protocols for trauma should not be different regardless of whether or not the person had a parent who experienced trauma. New and exciting behavioral treatments for fear and trauma are being developed and should be discussed.

PTSD Treatments: Ketamine, MDMA, oxytocin

  • Ketamine assisted psychotherapy and MTMA assisted psychotherapy are drug treatments being explored as potential therapeutics for PTSD.
  • Currently, ketamine is legally approved and prescribed by board certified physicians in the US, while MTMA is still illegal to possess or sell.
  • Ketamine works by creating a state of dissociation in which the individual can recount their trauma while feeling different emotional experiences than originally experienced.
  • MTMA is unique in that it leads to massive increases in both dopamine and serotonin simultaneously, creating feelings of connection and euphoria. This chemical milieu allows for the fast relearning of a new narrative associated with the trauma, compacting the typical process of trauma and fear reduction into a much shorter session.
  • These drugs are still illegal and clinical trials are currently being conducted to explore their potential.

How Do You Know If You Are Traumatized?

  • Trauma and fear can be measured by the balance between our perception of the external world and our internal bodily sensation.
  • A recent paper published in the journal Science looked at the role of the insular cortex in mice, which is associated with interoception and is responsible for determining if our internal sensations are reasonable given the external circumstances.
  • The paper showed that inhibiting the insula led to a range of different internal effects when faced with a mild or intense shock.
  • Furthermore, it is possible to recalibrate this relationship and reduce fear and trauma experienced in response to a memory or a real event. This process can be done quickly and is under our control.

Deliberate Brief Stress Can Erase Fears & Trauma

  • This study focused on the effects of repeated exposure to short-term behavioral stress in mice in relation to pre-existing stress induced depressive-like behavior.
  • The research showed that daily short bouts of intense stress reversed the effects of chronic stress in mice. The study pointed to a actionable protocol that may be implemented into clinical settings soon.
  • Additionally, similar research is being conducted by the author's lab focused on how five minute a day respiration protocols can alleviate stress in humans. The research is showing impressive and significant effects on stress reduction from both calming and arousal respiration protocols.

Erasing Fears & Traumas In 5 Minutes Per Day

  • Dr. David Spiegel is an MD psychiatrist and PhD who believes it's not just the state that you are in or that you go into when it comes to treating trauma, anxiety and PTSD, but how you got there and whether or not you had anything to do with it.
  • To recalibrate the system, a breathing protocol called cyclic sigh can be used which involves double inhale through the nose and a long exhale through the mouth to induce relaxation.
  • Alternatively, cyclic hyperventilation can be used which is a five minute-a-day protocol of very deep inhales and exhales with a full exhale and holding one's breath for 25 to 60 seconds every 25 or 30 breaths.
  • Both protocols have been found to have positive results, however, caution should be taken when engaging in them as they can be very stimulating and trigger panic and anxiety attacks. Deliberate entry into a short bout of stress is a very promising approach and can be done in conjunction with support from a clinician.

Nutrition, Sleep, & Other General Support Erasing Fear & Trauma

  • The foundation of good mental and physical health is key to overcoming fear and trauma. Quality nutrition, regular and sufficient sleep, and social connection are essential elements of this foundation.
  • Sleep is particularly important as it helps to reset the balance of the body's autonomic nervous system, allowing for a better functioning of its fear circuitry.
  • Without these elements, attempts to work through trauma can be hindered. Social connection also helps to provide both a sense of support and chemical suppression of fear.

Supplements for Anxiety, Fear: Saffron, Inositol, Kava

  • Supplementation can be a helpful tool for managing anxiety, stress, fear, and PTSD. Ashwagandha and saffron have proven to be effective in reducing anxiety, with 12 studies showing significant effects across males and females.
  • NAC has also been shown to reduce anxiety symptoms, with doses as high as 18 grams taken for a full month.
  • Kava has also been studied and has been found to be effective in reducing depressive symptoms and generalized anxiety, with doses ranging from 50-300 milligrams.
  • It is important to proceed with caution when trying any of these supplements and to check with a doctor regarding safety.


  • This podcast discussed a large amount of information about the biology of pathways in the brain and body that underlie the fear response and can lead to trauma and PTSD.
  • It touched on a variety of approaches to dealing with fear, trauma and PTSD that exist in the clinical landscape, as well as some emerging themes.
  • It is important to understand and think about the logical structure of the circuits that underlie fear and PTSD in order to find the most effective treatment.
  • Re-exposure to a traumatic event can be helpful, but should be done in a safe, supportive environment with the help of a professional. There are also some self-directed practices that may be reasonable for people experiencing fear that are not in need of extreme clinical treatment.