How the Brain Senses Gravity — with Elisa Ferrè

Dr Lachlan Kent and Dr Brennan Spiegel are joined by Elisa R. Ferrè, professor of cognitive neuroscience at Birkbeck, University of London, and one of the world’s leading experts on graviception and the vestibular system.Together, they explore how the brain senses gravity without a single “gravity receptor,” why the vestibular system has no primary cortex, and how gravity is computed as a distributed, multisensory model integrating vestibular, visual, proprioceptive, and visceral signals. The conversation spans neuroscience, emotion, aesthetics, culture, spaceflight, and mental health—revealing gravity as the hidden scaffolding of perception, meaning, and wellbeing.1. What Is Graviception?The brain’s ability to sense and model gravityNot driven by a single receptor or cortical areaConstructed through multisensory integrationFundamental to embodiment, orientation, and survivalWhy the Vestibular System Is UniqueNo unimodal “vestibular cortex”Projects broadly across the brainDoes not produce a clear conscious sensationBecomes noticeable mainly when something goes wrong (dizziness, vertigo, nausea)The vestibular system acts as the glue binding mind and body, anchoring us in a single embodied perspective.How the Brain Computes GravityGravity is not perceived directlyThe brain integrates:Vestibular otolith signals (head tilt, linearacceleration)Visual cues (verticality, alignment)Proprioception (joints, muscles, posture)Visceral signals (internal organs)Each signal is weighted by reliability to form an internal model of terrestrial gravity.Gravity, Meaning, and CulturePreferences for verticality (upright lines, tall buildings)Vertical = power, stability, positivityDownward tilt = unease, disorderGravity shapes art, architecture, language, and metaphorUp = good, free, elevatedDown = heavy, negative, constrainedEmotion, Fear, and the Vestibular SystemVestibular pathways connect directly to:AmygdalaInsulaHypothalamusThis explains why vestibular disturbances are emotionally chargedDizziness and vertigo trigger fear, nausea, and autonomic responsesGravity sensing is deeply tied to survival systemsWeightlessness and FreedomParabolic flight (“vomit comet”) as a unique graviceptive stateWeightlessness described as profound freedomAlso physiologically challengingPost-flight “down” feelings mirror return to gravityFreedom comes with a cost: sensory conflict and adaptation demands.Space Adaptation & NeuroplasticityAstronauts experience space motion sicknessSymptoms: nausea, disorientation, brain fogThe brain can adapt through neuroplasticityAdaptation takes time, energy, and trainingImplicationsfor long-term space travel and Mars exploration.Gravity, Mental Health, and Everyday LifeAnxiety as mis-tuned gravity anticipationDepression as altered temporal and bodily groundingMental fitness as trainable gravity resilienceTools discussed:Yoga and postureBreath awarenessGrounding through the feetWeighted blanketsMusic, rest, and multisensory regulationPractical Graviceptive TipStand still and feel the pressure through the soles of your feetNotice the security of 1GUse grounding as a way to reduce anxiety and reset expectationsTimecodes00:00 — Introduction & guest welcome02:00 — What makes the vestibular system unique05:00 — Why gravity is mostly unconscious06:30 — How the brain computes gravity09:30 — Homunculus vs gravity computation11:30 — Gravity as a prior for perception14:00 — Semantics, aesthetics & verticality17:00 — Architecture, art & meaning20:00 — Vestibular system & emotion22:00 — Parabolic flight & weightlessness24:00 — Freedom, addiction & the cost of zero-G28:30 — Space adaptation syndrome31:00 — Can humans adapt to Mars?35:30 — Everyday graviception & grounding38:00 — Closing reflectionsResourcesThe Gravity Doctors: https://thegravitydoctors.comDr Brennan Spiegel: https://brennanspiegelmd.comDr Lachlan Kent: https://lachlankent.au