1,240 articles
Sporadic Creutzfeldt-Jakob disease
Sporadic Creutzfeldt-Jakob disease (sCJD, sporadic CJD) is the most common human prion disease, about 85-90% of CJD cases, a rapidly fatal dementia with myoclonus, median onset age 65, incidence roughly 0.5-2 per million per year, no treatment.
Squamous cell carcinoma of conjunctiva
Squamous cell carcinoma of conjunctiva (CSCC, ICD-11 2D00.2) is the invasive malignant end of ocular surface squamous neoplasia, driven by UV exposure, HIV immunosuppression, and possibly HPV, commonest in Africa, treated by excision, topical chemotherapy, or radiotherapy.
Squid giant synapse
Squid giant synapse: large glutamatergic synapse in the squid stellate ganglion's giant fiber system (escape circuit), classical preparation that established calcium-triggered, quantal, nanodomain-coupled neurotransmitter release.
Stapes
Stapes: smallest bone of the human body, the third middle-ear ossicle, footplate seated in the oval window; discovered by Ingrassia in 1546 and central to otosclerosis surgery.
Stargardt disease
Stargardt disease (STGD1, fundus flavimaculatus), also called Stargardt macular degeneration or juvenile macular degeneration, is an inherited ABCA4-related retinal dystrophy causing childhood-onset central vision loss from lipofuscin buildup in the macula, with no approved treatment.
Startle Reflex
The startle reflex is an automatic whole-body reaction to a sudden intense stimulus, causing muscle contraction, limb flexion, eye blinking, and autonomic changes like accelerated heart rate.
Stellate neuron
Stellate neuron (Cell Ontology CL:0000122, stellate cell): a neuron with star-shaped radiating dendrites. Distinct populations exist in cerebellar molecular layer (GABAergic), neocortical layer 4 (excitatory spiny stellate), and entorhinal cortex layer II (grid-cell related).
Stent-electrode recording array
Stent-electrode recording array (Stentrode, Synchron): a nitinol stent with 16 platinum electrodes implanted via the jugular vein into the superior sagittal sinus to record vascular ECoG for brain-computer interfaces in paralysis; first-in-human SWITCH trial showed no serious adverse events over 12 months.
Stereotactic surgery
Stereotactic surgery: 3D coordinate-guided minimally invasive brain surgery, also called stereotaxis. Frame-based or frameless targeting for biopsy, functional neurosurgery, and radiosurgery; pioneered by Horsley-Clarke (1908) and Spiegel-Wycis (1947).
Stimulus (physiology)
Stimulus (physiology): a detectable environmental or internal change (light, sound, chemical, temperature, pressure) that activates sensory receptors. Key facts: transduction into graded receptor potentials, coding of modality, location, intensity, duration, and receptor adaptation.
Strabismus
Strabismus (squint) is misalignment of the eyes, affecting 2-5% of people. Types include esotropia, exotropia, hypertropia; treated with glasses, prisms, exercises, or eye muscle surgery, sometimes with adjustable sutures.
Straight leg raise
The straight leg raise, also called the Lasègue sign, lifts a patient's extended leg to detect lumbosacral nerve root irritation, most often evaluated in low back pain with sciatica.
Stretch reflex
Stretch (myotatic, deep tendon) reflex: involuntary muscle contraction on rapid stretch, via monosynaptic Ia afferent–alpha motor neuron spinal connections; basis of knee jerk, ~20 ms upper-limb latency, delayed 14 ms in older adults.
Striatal cholinergic-GABAergic neuron
A striatal cholinergic-GABAergic neuron, or CGIN, is a large aspiny striatal interneuron that releases both acetylcholine and GABA, making up about half of the striatum's cholinergic interneurons.
Subacute combined degeneration of spinal cord
Subacute combined degeneration (SACD, SCD) is vitamin B12 deficiency myelopathy of the dorsal and lateral spinal cord columns, causing sensory loss and spasticity; increasingly caused by nitrous oxide inactivation of B12.
Subdural hygroma
Subdural hygroma (SDHy, SDG): a subdural collection of pure CSF from traumatic arachnoid tearing or effusion in intracranial hypotension, dehydration, or atrophy; coined by Dandy 1934; may convert to chronic subdural hematoma.
Suboccipital nerve
The suboccipital nerve is the dorsal ramus of the C1 spinal nerve, a mainly motor nerve supplying the four suboccipital muscles and semispinalis capitis within the suboccipital triangle alongside the vertebral artery.
Substance P
Substance P (SP) is an 11-amino acid tachykinin neuropeptide, discovered 1931 by von Euler and Gaddum, sequenced 1971, signaling mainly through the NK1 receptor; its antagonists treat chemotherapy-induced nausea.
Substantia gelatinosa of Rolando
Substantia gelatinosa of Rolando (SGR), or substantia gelatinosa, is the translucent lamina II of the spinal dorsal horn, described by Rolando in 1824, that receives C and Aδ fiber input and modulates nociception via gate control circuitry.
Substantia nigra
The substantia nigra, Latin for "black substance", is a nucleus of the midbrain that supplies dopamine to the basal ganglia and helps modulate motor movement and reward.
Summation (neurophysiology)
Summation (neurophysiology): the combining of postsynaptic potentials in a neuron, via temporal summation from one input over time and spatial summation from multiple inputs, read out at the axon hillock; dendrites add linear, sublinear, and supralinear modes.
Superior canal dehiscence syndrome
Superior canal dehiscence syndrome (SCDS), a third-mobile-window inner ear disorder first described by Minor et al. in 1998, causing sound- and pressure-induced vertigo, autophony, and pulsatile tinnitus, diagnosed by Bárány criteria and repaired surgically.
Superior colliculus
Superior colliculus (optic tectum in non-mammals): paired layered midbrain structure integrating visual, auditory, and somatosensory maps to generate saccades, orient head and eyes, detect looming threats, and support attention and categorization.
Superior laryngeal nerve
Superior laryngeal nerve (nervus laryngeus superior), a vagus nerve branch dividing into an internal sensory branch to the supraglottic larynx and an external motor branch to the cricothyroid muscle; injury causes pitch-range loss and dysphagia.
Superior limbic keratoconjunctivitis
Superior limbic keratoconjunctivitis (SLK, Theodore's syndrome) is a chronic relapsing inflammation of the superior bulbar and tarsal conjunctiva and superior limbus, mainly in women aged 30–55, linked to thyroid eye disease and dry eye.
Superior olivary complex
Superior olivary complex (SOC), or superior olive: cluster of auditory nuclei in the caudal pontine tegmentum, first site of binaural convergence; MSO computes interaural time differences, LSO level differences, for sound localization.
Suprachiasmatic nucleus
Suprachiasmatic nucleus (SCN), hypothalamic master circadian pacemaker above the optic chiasm, ~20,000 neurons, intrinsic period ~24.2 h, light-entrained via the retinohypothalamic tract, synchronizes peripheral clocks and melatonin rhythms.
Sural nerve
Sural nerve: purely sensory lower-leg cutaneous nerve formed mainly by union of the medial sural cutaneous and peroneal communicating nerves; standard site for nerve conduction studies, nerve biopsy, and graft harvesting.
Surface chemistry of neural implants
Surface chemistry of neural implants: coatings (Pt, IrOx, PEDOT, graphene, hydrogels, drug-releasing layers) on neural electrodes that lower impedance, raise charge capacity, and suppress glial scar formation at the electrode–tissue interface.
Swartz Prize for Theoretical and Computational Neuroscience
The Swartz Prize for Theoretical and Computational Neuroscience is an annual award by the Society for Neuroscience, first given in 2008 to Wilfrid Rall and supported by the Swartz Foundation.