1,240 articles
Gaucher's disease
Gaucher's disease (Gaucher disease) is a rare autosomal recessive lysosomal storage disorder caused by GBA1 variants and glucocerebrosidase deficiency, with types 1, 2, and 3, treated by enzyme replacement or substrate reduction therapy.
Gene therapy of the human retina
Gene therapy of the human retina: AAV-mediated delivery of therapeutic genes to treat inherited retinal diseases and neovascular disorders. Luxturna (voretigene neparvovec, 2017) is the first approved product, for biallelic RPE65 retinal dystrophy.
Genetically encoded voltage indicators
Genetically encoded voltage indicators (GEVIs) are engineered fluorescent protein sensors that report membrane voltage optically, allowing noninvasive, cell-type-specific recording with millisecond resolution, mostly in neurons.
Genetics of amyotrophic lateral sclerosis
Genetics of ALS: 5–10% familial, 90–95% sporadic; C9orf72, SOD1, TARDBP, FUS are major genes; 2023 guidelines recommend universal testing; tofersen treats SOD1-ALS.
Giant papillary conjunctivitis
Giant papillary conjunctivitis (GPC), also called contact lens-associated papillary conjunctivitis (CLAPC), is an inflammation of the upper tarsal conjunctiva with giant papillae, mainly in contact lens wearers, causing itching, mucus, and lens intolerance.
Glasgow Coma Scale
Glasgow Coma Scale (GCS), by Teasdale and Jennett (Lancet 1974): rates eye, verbal, and motor responses; sum score 3–15; severity bands mild 13–15, moderate 9–12, severe <8; standard consciousness assessment in head injury.
Glaucoma
Glaucoma is a group of eye diseases damaging the optic nerve and causing irreversible vision loss; types include open-angle (9 in 10 US cases), angle-closure, congenital, and normal-tension glaucoma, treated by pressure-lowering drops, laser, and surgery.
Glaucoma Drainage Implants
Glaucoma drainage implants (aqueous shunts, tube shunts; Molteno, Baerveldt, Ahmed) are silicone tube-and-plate devices that drain aqueous humor to lower eye pressure in refractory glaucoma, in valved and non-valved designs.
Glaucoma suspect
Glaucoma suspect (borderline glaucoma; ICD-11 9C60, ICD-10 H40.0): a person with elevated IOP, suspicious optic nerve, visual field, or angle findings, or family history, at risk of future glaucoma but not yet glaucomatous.
Glaucoma-ectopia lentis-microspherophakia-stiff joints-short stature syndrome
GEMSS syndrome (glaucoma-ectopia lentis-microspherophakia-stiff joints-short stature), also called Weill-Marchesani syndrome 2, is a rare autosomal dominant FBN1-related disorder with lens dislocation, glaucoma, short stature, and progressive joint stiffness.
Glaucomatous optic neuropathy
Glaucomatous optic neuropathy is the characteristic optic nerve damage in glaucoma, marked by progressive retinal ganglion cell death, optic nerve head excavation, and visual field loss.
Glia
Glia (neuroglia) are the non-neuronal cells of the nervous system: astrocytes, oligodendrocytes, microglia, ependymal cells, and Schwann cells. Named by Virchow (1856), they myelinate axons, form the blood-brain barrier, and outnumber neurons only about 1:1.
Glioblastoma
Glioblastoma (GBM, glioblastoma multiforme, grade IV astrocytoma): the most common and aggressive primary adult brain tumor, a fast-growing glial CNS neoplasm treated with surgery, radiotherapy, and temozolomide; median survival about 15 months.
Glossopharyngeal nerve
Glossopharyngeal nerve (CN IX, nervus glossopharyngeus): ninth cranial nerve from the medulla exiting via the jugular foramen; supplies stylopharyngeus, parotid gland, posterior third of tongue taste, carotid sinus and body; linked to glossopharyngeal neuralgia.
Glutamate receptor
Glutamate receptor (GluR), ionotropic (AMPA, kainate, NMDA, GluD) and metabotropic families, receptors for glutamate, the brain's main excitatory neurotransmitter; 18 iGluR genes, tetrameric channels, central to synaptic plasticity and neuropsychiatric disease.
God helmet
God helmet, or Koren helmet, a device by Michael Persinger applying weak temporal-lobe magnetic fields to induce a sensed presence; double-blind and placebo studies attribute reported experiences to suggestibility, not the fields.
Golgi tendon reflex
Golgi tendon reflex (inverse myotatic reflex, autogenic inhibition): spinal reflex where Golgi tendon organ Ib afferents disynaptically inhibit the contracting muscle's alpha motor neurons and excite antagonists; task-dependent, not just protective.
Golgi's method
Golgi's method (reazione nera), Camillo Golgi's 1873 silver impregnation technique, stains 1–5% of neurons fully black; basis of the neuron doctrine debate with Cajal and still used for single-neuron morphology.
Granular corneal dystrophy type I
Granular corneal dystrophy type I (GCD1, Groenouw type I, classic GCD): rare autosomal dominant TGFBI p.Arg555Trp stromal corneal dystrophy with childhood-onset breadcrumb-like corneal deposits, glare, erosions, and progressive visual impairment.
Granular corneal dystrophy type II
Granular corneal dystrophy type II (GCD2, Avellino corneal dystrophy) is an autosomal dominant TGFBI (R124H) stromal corneal dystrophy with hyaline and amyloid deposits, common in East Asia, exacerbated by refractive surgery, treated with PTK and keratoplasty.
Granule cell
Granule cell: a very small vertebrate CNS neuron; covers cerebellar granule cells (parallel fibers, mossy fiber input), axonless GABAergic olfactory bulb granule cells, and dentate gyrus principal neurons doing pattern separation.
Grayson-Wilbrandt corneal dystrophy
Grayson-Wilbrandt corneal dystrophy (GWCD), also called Grayson-Wilbrandt-Hornhautdystrophie, is an extremely rare, questionable Bowman layer corneal dystrophy described in one 1966 family; autosomal dominant, removed from IC3D edition 3.
Group C nerve fiber
Group C nerve fibers (C fibers, group IV) are unmyelinated, 0.2-1.5 micrometer peripheral axons conducting at 0.5-2 m/s, carrying slow burning pain, temperature, and itch, distinguished from myelinated A fibers.
Growth cone
Growth cone: the motile, sensory tip of a growing axon, first described by Cajal in 1890, that steers axon pathfinding via actin-driven filopodia and attractive or repulsive guidance cues such as netrins and semaphorins.
Gut–brain axis
Gut–brain axis (microbiota–gut–brain axis): bidirectional communication network linking the central and enteric nervous systems and gut microbiota via vagal, HPA-axis, immune, and metabolite signaling; studied in IBS and neuropsychiatric disease.
Habituation
Habituation: progressive decrease of a response to repeated stimulation, not caused by sensory adaptation or fatigue; distinguished by dishabituation, stimulus specificity, and spontaneous recovery; HPA axis habituates rapidly to repeated stress.
Hand–eye coordination
Hand–eye coordination (eye–hand coordination, EHC): using visual information to guide manual movements like reaching and grasping. Defined by sequential visual-to-motor processing, posterior parietal control, tests such as the Purdue Pegboard, and reliability ICCs of 0.80–0.94.
Handedness
Handedness, or hand preference, is the tendency to favor one hand for tasks; about 10.6% of people are left-handed, with the roughly 1:10 right-left ratio shaped by evolution and moderated by culture.
Head Movements
Head movements: voluntary or involuntary motion of the head in humans and animals (MeSH D019416). Covers gaze stabilization via the vestibulo-ocular reflex, head impulse testing, active versus passive movement effects, and nonverbal communication roles.
Head-related transfer function
Head-related transfer function (HRTF): direction-dependent acoustic filter of sound by a listener's head, pinnae, and torso, measured at the ear canal entrance; listener-specific like a fingerprint, basis of binaural VR audio, carrying ITD, ILD, and spectral localization cues.