Podcast Summary: “The Great Balancing Act: An Insider’s Guide to the Human Vestibular System”

Podcast: New Books Network
Host: Gregory McNiff
Guest: Dr. Jeffrey D. Sharon
Date: October 21, 2025

Overview

This episode features Dr. Jeffrey D. Sharon, director of the Balance and Fall Center and associate professor at UCSF, discussing his new book, "The Great Balancing Act: An Insider’s Guide to the Human Vestibular System" (Columbia UP, 2025). The conversation blends accessible neuroscience, fascinating history, clinical insights, and Sharon’s own humor and empathy to reveal how the vestibular system — often called the “hidden sense” — is vital to virtually every aspect of human experience, from movement and balance to memory, emotion, and even abstract thought.

Key Discussion Points & Insights

Why Write About the Vestibular System?

• Sharon’s clinical experience treating dizziness, vertigo, and balance patients revealed a trove of under-discussed science and human stories.
• The book is written in an accessible, engaging style, suited for the general public as well as students, clinicians, and patients.

  "There was this pretty interesting story out there that just hadn't been told before...about its evolution, about how it's important not just for medicine and health, but for normal functioning, for thinking." — Jeffrey Sharon [02:43]

What is the Vestibular System? (06:35)

• Jokingly called the “sixth sense”—not traditionally taught among the senses—it's the body’s way of detecting gravity, movement, and head orientation.
• Present in the inner ear alongside the cochlea (hearing organ), composed of gravity-sensing organs and semicircular canals.
• Analogous to technology: Planes, iPhones, and other devices have similar “vestibular” analogs.

  "It's our inner ear's ability to sense movement, to sense gravity, and to sense rotations and turns and tilts and things like that..." — Jeffrey Sharon [05:21]

Core Terminology (Somatosensation & Proprioception) (06:57)

• Somatosensation: Broad term for touch and bodily awareness.
• Proprioception: Specifically sensing limb position in space; a subset of somatosensation.
• Balance is multisensory: Integrates vision, somatosensation, vestibular input.

Evolutionary Context: The Universal Need to Sense Gravity (14:28)

• Virtually every animal, from jellyfish to elephants, possesses a system for detecting gravitational orientation.
• The vestibular system’s “form follows function”: The evolutionary structure reflects its gravitational sensing purpose.
• Diseases sometimes result from these design principles—e.g., misplaced “ear crystals” lead to vertigo.

Anatomy Highlights: The Elegance of Inner Ear Design (17:01)

• The cochlea (hearing) and semicircular canals (balance) utilize specialized “hair cells” responsive to fluid and movement.
• The semicircular canals are three interlocking rings, matching the cardinal axes of motion and eye movement.

  "You don't realize your head has three interlocking circles inside of it, the width of each millimeter across of these circles." — Jeffrey Sharon [17:01]

• Humans’ hearing is uniquely sensitive — we detect microscopic movements smaller than an atom.

The Physics of Balance: Fluid, Forces, and Symmetry (19:34)

• Semicircular canals detect rotation via endolymph (fluid) and “cupula” apparatus—sensitive to inertia.
• Resting nerve firing rate allows encoding direction and speed of movement despite neural binary limitations.

  "If you want to be able to sense head turns…how do you design a system that can encode right movements and left movements when the only thing the nerve could do is just fire? And the solution the body has is to have a resting rate of nerve firing." — Jeffrey Sharon [21:48]

Unexpected Physics: The Lorenz Force in MRIs (25:39)

• Intriguingly, people sometimes get dizzy or their eyes “twitch” (nystagmus) in MRI machines; this is due to electrical fields produced by vestibular organs interacting with the MRI magnet, producing a Lorenz force that fools the system.

Historical Discoveries and Key Figures (30:55)

• Highlights contributions from Ramón y Cajal (brain architecture), Mach (acceleration over velocity), Breuer (both vestibular and psychoanalysis), and Prosper Ménière.
• Vestige of late scientific discovery: Most vestibular breakthroughs are from the late 19th and early 20th centuries.

Vestibular System and Cognition (34:07)

• Loss of vestibular function leads to “brain fog” and spatial disorientation.
• The brain relies on vestibular input for forming mental maps—cells (place cells, head direction cells) act as an internal GPS.

  "We cannot form a mental map of the world around us without the vestibular system." — Jeffrey Sharon [34:07]

• Abstract thinking and language about ideas often borrow from spatial metaphors, possibly reflecting shared neural architecture.

Challenges in Language and Medicine (37:49)

• There’s no word for loss of vestibular sensation (unlike “blind” or “deaf”), reflecting its conceptual neglect.
• Vestibular disorders often overlap with anxiety ("the story there isn't fully understood"), and effective treatment often requires addressing both.

  "We don't have a word for someone who can't accurately use their vestibular system." — Jeffrey Sharon [37:49]

The Brain Does Calculus (39:47)

• Vestibular inputs encode acceleration, but to keep eyesight stable, the brain “integrates” this into velocity and position—much like the mathematical process.

  "Everyone's brain can do calculus." — Jeffrey Sharon [39:47]

Clinical Outcomes: Diseases of the Vestibular System (43:29)

• Definition and experience of vertigo: "an illusory sensation of movement."
• Migraine can manifest mostly as vertigo/dizziness.
• Ménière’s disease remains mysterious and treatments are often destructive due to inability to biopsy the inner ear.

  "We still don't have any—we have zero FDA approved treatments for Meniere's disease." — Jeffrey Sharon [47:12]

Cutting-Edge Therapies: Implants & Genetics (49:50)

• Cochlear implants are one of the most successful neural prosthetics, restoring hearing by electrically stimulating the auditory nerve.

  "The cochlear implant is arguably the most successful neural prosthesis of all time." — Jeffrey Sharon [49:50]

• Vestibular implants (still under study) may soon similarly restore balance.
• Gene therapy breakthroughs (like for Otoferlin mutation) have begun restoring hearing in congenital deafness, raising hope for broader cures.

Life in Space: Vestibular System’s Terrestrial Limit (57:29)

• Semicircular canals function in zero-gravity, but gravity-sensing crystals do not—causing profound disorientation for astronauts.
• Without artificial gravity, adaptation or long-term space habitation presents major neurological challenges.

Practical Advice for Patients (60:25)

• Both neurologists (brain) and ENTs (ear) can treat vestibular disorders, but patients often fall through the cracks.
• Look for vestibular specialists or vestibular-trained physical therapists for optimal care.
• Empathetic listening and patient-centered care remain the cornerstone; knowledge is important, but connection and understanding truly matter.

  "Empathy is essential to medicine. It's really critical. Our patients come to us in this unique moment of vulnerability..." — Jeffrey Sharon [63:38]

Notable Quotes & Memorable Moments

• On Scope & Purpose:

  “I really wrote it for the general public.” — Jeffrey Sharon [04:18]

• On Evolution:

  “If you understand the design, you understand the need, you understand the purpose, then you can understand the predictable failures that happen.” — Jeffrey Sharon [14:28]

• On Anatomy:

  “You don't realize your head has three interlocking circles inside of it...” — Jeffrey Sharon [17:01]

• On Cognition:

  “We cannot form a mental map of the world around us without the vestibular system.” — Jeffrey Sharon [34:07]

• On Language:

  “We don't have a word for someone who can't accurately use their vestibular system.” — Jeffrey Sharon [37:49]

• On Calculus in the Brain:

  “Everyone's brain can do calculus.” — Jeffrey Sharon [39:47]

• On Ménière’s Disease:

  “We still don’t have any—we have zero FDA approved treatments for Ménière’s disease.” — Jeffrey Sharon [47:12]

• On Breakthroughs:

  “For the first time in history, we're now able to treat hearing loss with a gene therapy.” — Jeffrey Sharon [54:46]

• On Practicing Medicine:

  “Empathy is essential to medicine. It’s really critical. Our patients come to us in this unique moment of vulnerability...and at least try their best for me.” — Jeffrey Sharon [63:38]

Key Timestamps (MM:SS)

• 02:43: Why Dr. Sharon wrote the book & the importance of the vestibular system
• 05:21: What is the vestibular system?
• 06:57: Somatosensation/proprioception and balance
• 14:28: Evolution and “form follows function” in the vestibular system
• 17:01: The elegance of the cochlea and semicircular canals
• 19:34: Physics of endolymph, hair cells, and balance
• 21:48: Symmetry/asymmetry in vestibular nerve coding
• 25:39: MRI dizziness and the Lorenz force
• 30:55: History: Ramón y Cajal, Mach, Barany
• 34:07: Vestibular system’s role in cognition and mental mapping
• 37:49: The challenge of language for vestibular deficits
• 39:47: The brain’s calculus: acceleration vs velocity vs position
• 43:29: What is vertigo? The link with anxiety
• 47:12: Ménière’s Disease and the limits of current treatment
• 49:50: Cochlear and upcoming vestibular implants; future medicine
• 54:46: Gene therapy and regenerative breakthroughs
• 57:29: Vestibular dysfunction in space travel
• 60:25: Practical advice for patients seeking treatment
• 63:38: The role of empathy and connection in medicine

Takeaways

• The vestibular system is foundational to everyday life but remains underestimated.
• Its loss can profoundly affect cognition, perception, and emotional well-being.
• New therapies—implants and gene therapy—offer hope for future restoration of hearing and balance.
• Empathetic care, humor, and patient education sit at the heart of effective medicine.

Recommended for: Anyone curious about the hidden mechanisms that keep us balanced—literally and figuratively.