Nervous and sensory systems

Vestibular hair cell

Vestibular hair cell, also called vestibular sensory hair cell (type I and type II), is the inner ear mechanoreceptor that transduces head motion and gravity into vestibular nerve signals; type I cells have calyx endings, type II bouton endings, and mammals regenerate them poorly.

Vestibular implant

A vestibular implant is an implanted neurostimulator that restores balance by electrically stimulating the vestibular nerve in people with bilateral vestibular hypofunction, first implanted in 2007 and still investigational.

Vestibular migraine

Vestibular migraine (migrainous vertigo) is a migraine subtype causing recurrent vertigo, defined by Bárány Society/IHS criteria; affects 1–3% of people, treated with propranolol, valproate, venlafaxine, CGRP antibodies, and vestibular rehabilitation.

Vestibular nerve

Vestibular nerve: balance branch of cranial nerve VIII, with bipolar neurons in Scarpa's ganglion carrying signals from utricle, saccule, and semicircular canals to four vestibular nuclei; distinct from the cochlear (hearing) branch.

Vestibular neuritis

Vestibular neuritis, also known as acute unilateral vestibulopathy, is a sudden loss of vestibular nerve function on one side, causing severe vertigo for days while hearing stays normal.

Vestibular nuclei

Vestibular nuclei: four paired brainstem nuclei (superior of Bechterew, medial of Schwalbe, lateral of Deiters, inferior of Roller) under the fourth ventricle relaying vestibular nerve input for gaze, posture, autonomic, and perceptual functions.

Vestibular rehabilitation

Vestibular rehabilitation (VRT, vestibular physical therapy) is exercise-based physical therapy for peripheral vestibular hypofunction, using gaze stabilization, habituation, balance and gait exercises; strong guideline evidence supports it, unlike isolated eye-movement exercises.

Vestibular schwannoma

Vestibular schwannoma (acoustic neuroma) is a benign Schwann-cell tumor of the vestibulocochlear nerve causing unilateral hearing loss, tinnitus, and imbalance; managed by observation, radiosurgery, or microsurgery, with bilateral tumors signaling NF2.

Vestibular system

The vestibular system, or labyrinth, is the inner-ear sensory system detecting head motion and gravity via three semicircular canals and the utricle and saccule, enabling balance, gaze stabilization (VOR), and spatial orientation; disorders cause vertigo and imbalance.

Vestibulo–ocular reflex

Vestibulo–ocular reflex (VOR, oculovestibular reflex): automatic eye reflex stabilizing vision during head motion, gain normally 1, tested by head impulse, vHIT, caloric, and rotary chair tests.

Vestibulocochlear nerve

Vestibulocochlear nerve (CN VIII, acoustic nerve): purely sensory eighth cranial nerve carrying hearing from the cochlea and balance from the vestibular organs through the internal auditory canal to brainstem nuclei.

VGR-R01 (CYP4V2 AAV8 gene therapy)

VGR-R01 (rAAV2/8-CYP4V2) is Shanghai Vitalgen's subretinal AAV8 gene therapy delivering codon-optimized human CYP4V2 for Bietti crystalline dystrophy; phase 1/2 showed BCVA gains, phase 3 completed, NDA accepted by China CDE in June 2026.

Viral conjunctivitis

Viral conjunctivitis (adenoviral pink eye) is a highly contagious acute conjunctival infection, usually adenovirus, causing red watery eyes; clinical diagnosis, supportive care, resolves in 7-14 days.

Viral retinitis

Viral retinitis: herpesvirus infection of the retina, mainly acute retinal necrosis (VZV, HSV), progressive outer retinal necrosis, and CMV retinitis in immunocompromised patients; necrotizing, retinal detachment-prone, treated with systemic and intravitreal antivirals.

Vision research

Vision Research (ISSN 0042-6989) is an Elsevier peer-reviewed journal of human, vertebrate, and invertebrate visual function, founded in 1961 in England, MEDLINE-indexed since 1964, publishing research, reviews, and special issues on vision.

Visual acuity

Visual acuity (VA): the eye's spatial resolving capacity, measured as the reciprocal of the minimum angle of resolution; 20/20 equals 1 arcmin. Tested with Snellen, Landolt C, and logMAR/ETDRS charts.

Visual Evoked Potentials

Visual evoked potentials (VEPs, visual evoked responses) are averaged EEG signals from the occipital cortex in response to pattern or flash stimuli, used clinically to assess optic nerve and visual pathway function, notably prolonged P100 latency in optic neuritis and multiple sclerosis.

Visual field

Visual field: the full area visible with fixed gaze, about 160 degrees horizontal per eye. Measured by perimetry (Goldmann, Humphrey SAP, kinetic, microperimetry); field defect patterns localize glaucoma and neurologic lesions.

Visual phototransduction

Visual phototransduction, also called the phototransduction cascade, is the process by which retinal rod and cone cells convert absorbed light into electrical responses via a G protein cascade.

Visual prosthesis

Visual prosthesis (bionic eye): implantable device restoring rudimentary sight by electrically stimulating surviving retinal or cortical neurons; approved devices include Argus II, IRIS II, Alpha IMS/AMS; acuity stays below legal blindness.

Visual system

Visual system: the neural pathway converting light into perception, from retinal phototransduction through optic nerve, chiasm, LGN, and visual cortex; also called the visual pathway, with retinotopic organization and localizable field defects.

Vitrectomy

Vitrectomy is eye surgery removing vitreous gel to treat retinal diseases, such as detachment and macular holes; the procedure replaces the gel with saline, gas, or oil.

Vitreous body

Vitreous body (vitreous humor, corpus vitreum): transparent gel filling the eye between lens and retina, about 80% of ocular volume, 98-99.7% water with type II collagen and hyaluronan; develops in three phases and liquefies with age.

Vocal cord paresis

Vocal cord paresis, or vocal fold paresis, is partial weakness of a vocal fold from incomplete laryngeal nerve denervation, between normal function and full paralysis; it causes glottic insufficiency, breathy voice, and is diagnosed with laryngoscopy plus laryngeal EMG.

Oct 15, 2026

Vollum Institute

The Vollum Institute, founded in 1987 and named for philanthropists Howard and Jean Vollum, is a privately endowed neuroscience research institute at Oregon Health & Science University in Portland, Oregon.

Voretigene neparvovec

Voretigene neparvovec (Luxturna) is an AAV2-based gene therapy delivering the human RPE65 gene for biallelic RPE65 mutation-associated retinal dystrophy; FDA-approved December 19, 2017, EU-approved November 22, 2018, given by subretinal injection.

Voxel-based morphometry

Voxel-based morphometry (VBM) is an MRI neuroimaging method comparing gray matter voxel-wise between groups via normalization, segmentation, smoothing, and statistical parametric mapping; introduced by Ashburner and Friston (2000), distinct from surface-based morphometry.

VRandMRI study

VRandMRI (NCT05098587) is a completed observational pilot study by Swiss Paraplegic Research, Nottwil, testing whether Virtual Walk therapy changes pain perception, BOLD fMRI activity, and MRS metabolites in 12 SCI patients with neuropathic pain.