1,240 articles
Retinopathy of prematurity
Retinopathy of prematurity (ROP), formerly retrolental fibroplasia, is abnormal retinal blood vessel growth in babies born before 30 weeks or under about 3 pounds; staged 1 to 5, screened by dilated exam, treated with laser, anti-VEGF injections, or surgery.
Retrograde amnesia
Retrograde amnesia is loss of memories formed before the causative event, unlike anterograde amnesia. Key features: Ribot's law temporal gradient, medial temporal lobe damage, consolidation versus retrieval theories, and functional (dissociative) forms.
Revakinagene taroretcel lwey
Revakinagene taroretcel-lwey (ENCELTO, NT-501) is a Neurotech Pharmaceuticals encapsulated cell gene therapy implant releasing CNTF, FDA-approved March 5, 2025 as the first treatment for adults with idiopathic macular telangiectasia type 2.
Review and annual journals in neuroscience
Review and annual journals in neuroscience, chiefly the Annual Review of Neuroscience (est. 1978, ISSN 0147-006X) and Nature Reviews Neuroscience (est. 2000), publish commissioned surveys of the field rather than primary research, with distinct open access and subscription models.
Reward system
Reward system: brain circuitry (VTA, nucleus accumbens, ventral pallidum, prefrontal cortex) mediating wanting, liking, and learning. Dopamine encodes prediction errors and incentive salience, not pleasure itself; dysfunction links to addiction, depression, Parkinson's.
Rhabdoid tumor predisposition syndrome
Rhabdoid tumor predisposition syndrome (RTPS, RTPS1/RTPS2) is a rare autosomal dominant hereditary cancer syndrome caused by germline SMARCB1 or SMARCA4 variants, predisposing infants to aggressive rhabdoid tumors (ATRT, kidney, soft tissue) with over 90% penetrance by age 5.
Rhodopsin
Rhodopsin: the rod-cell GPCR photoreceptor of scotopic vision, composed of opsin plus 11-cis-retinal; first GPCR crystal structure, Meta II activates transducin, mutations cause retinitis pigmentosa.
RIDE trial
RIDE (NCT00473382), with sister trial RISE, was a phase 3 sham-controlled trial of monthly intravitreal ranibizumab (0.3 mg, 0.5 mg) for diabetic macular edema; 382 patients, ≥15-letter ETDRS gains at 24 months, basis of 2012 US approval.
Righting Reflex (medicine)
The righting reflex is the inborn impulse to return the body to its normal orientation in space after displacement; its loss is a standard measure of unconsciousness in rodent research.
Riluzole
Riluzole (Rilutek, Tiglutik, Exservan) is an antiglutamatergic drug for ALS, FDA-approved in 1995; it prolongs median survival by two to three months and remains the only globally approved disease-modifying ALS therapy.
Rinne test
Rinne test: bedside tuning-fork hearing test comparing air versus bone conduction to detect conductive hearing loss; described by Rinne in 1855 (earlier by Polansky 1842), positive when air conduction is better.
Rivastigmine
Rivastigmine (Exelon) is a carbamate cholinesterase inhibitor for Alzheimer's and Parkinson's disease dementia, given orally or as a 4.6-13.3 mg/24 h patch; dual AChE/BuChE inhibition, GI side effects predominate.
Robert Sapolsky
Robert M. Sapolsky, Stanford neuroendocrinologist and primatologist; glucocorticoid cascade hypothesis, Kenyan baboon rank-stress studies, Behave and Determined, MacArthur Fellow, free-will denial debate.
Rod cell
Rod cell: retinal photoreceptor mediating scotopic (night) vision via rhodopsin; single-photon sensitivity, outer segment of 1000–2000 disks, absent from fovea, saturates in bright light, unlike cones.
Romberg's test
Romberg's test: bedside balance test, feet together, eyes open then closed; positive when balance is lost with eyes closed, indicating dorsal column proprioceptive loss; variants include sharpened tandem Romberg and CTSIB.
S-antigen
S-antigen (retinal S-antigen, 48-kDa protein, arrestin-1, gene Sag) is a retinal photoreceptor protein that binds light-activated phosphorylated rhodopsin to shut off phototransduction, first identified in 1977 as a uveitis-inducing autoantigen.
Saccade
Saccade: rapid ballistic eye movement (up to ~500 deg/s, under 100 ms) shifting gaze between targets onto the fovea; also called saccadic eye movement. Controlled by brainstem burst neurons, superior colliculus, and frontal eye field; kinematics follow the main sequence.
Sacral and coccygeal spinal nerves
The sacral and coccygeal spinal nerves are five pairs of sacral nerves (S1–S5) and one coccygeal nerve, the lowest spinal nerves, supplying the pelvis and lower limb.
Sacral plexus
Sacral plexus (plexus sacralis): pelvic nerve network formed by the lumbosacral trunk (L4, L5) and S1–S4, anterior to piriformis; gives the sciatic, gluteal, posterior femoral cutaneous, perforating cutaneous, and pudendal nerves and the S2–S3 parasympathetic outflow.
Salience (neuroscience)
Salience (neuroscience): the prominence of stimuli that captures attention, computed by the salience network (anterior insula, dorsal ACC). Covers saliency/priority maps, the DMN/CEN switching hypothesis, incentive salience, aberrant salience in psychosis, and 2024 depression findings.
Saliency map
A saliency map is a two-dimensional map showing which locations in a visual scene stand out or, in machine learning, which inputs influence a model's prediction.
Salk Institute for Biological Studies
Salk Institute for Biological Studies: independent nonprofit biological research institute founded 1960 by Jonas Salk in La Jolla, California; Louis Kahn-designed landmark campus, NCI-designated basic cancer center, discoveries in phosphorylation, neurohormones, and neurogenesis.
Sanpaku (三白)
Sanpaku (三白, "three whites") is a Japanese face-reading term for eyes with sclera visible on three sides of the iris; yin (below) and yang (above). Western medicine calls it scleral show, usually a normal eyelid-position feature, sometimes from thyroid eye disease.
SARM1
SARM1 (sterile alpha and TIR motif containing 1), also called SARM or SAMD2, is a human NAD+-cleaving enzyme on chromosome 17q11.2 that executes programmed axon degeneration after injury and is a neuroprotective drug target.
Scapuloperoneal spinal muscular atrophy
Scapuloperoneal spinal muscular atrophy (SPSMA, neurogenic scapuloperoneal amyotrophy, New England type) is a rare autosomal dominant TRPV4-related motor neuron disease causing scapular and peroneal muscle atrophy, laryngeal palsy, and distal weakness.
Schwann cell
Schwann cell: PNS glial cell (Theodor Schwann, 1839) forming myelin sheaths of peripheral axons, one internode per cell, derived from neural crest; transdifferentiates into repair cells after injury and is used in nerve repair and spinal cord injury trials.
Schwannoma
Schwannoma, also called neurilemmoma, is a usually benign nerve sheath tumor arising from Schwann cells, the most common peripheral nerve tumor in adults, often on the vestibular nerve.
Sciatic nerve
Sciatic nerve: largest human nerve, from L4–S3 roots, exiting the pelvis below piriformis and dividing into tibial and common peroneal nerves near the knee; supplies posterior thigh and most leg and foot motor and sensory function.
Sciatica
Sciatica: pain radiating from the buttock down the leg from sciatic nerve irritation or compression, usually a herniated lumbar disc; up to 43% lifetime prevalence, mostly self-limiting, with surgery offering only short-term benefit.
Sclera
The sclera is the tough white fibrous outer coat of the eye, about 85% of the outer tunic, spanning cornea to optic nerve; type I collagen-rich, strain-stiffening, linked to myopia, glaucoma, and scleritis.