1,240 articles
Dorsal root of spinal nerve
Dorsal root of spinal nerve (posterior root): the entirely sensory bundle of afferent axons, with cell bodies in the dorsal root ganglion, carrying touch, pain, and temperature from the periphery into the spinal cord's dorsal horn.
Dorsolateral prefrontal cortex
Dorsolateral prefrontal cortex (DLPFC, dlPFC), Brodmann areas 9 and 46 in the middle frontal gyrus: executive-control hub for working memory manipulation, planning, and self-control, and a leading tDCS/TMS target in depression and other neuropsychiatric disorders.
Dorzolamide
Dorzolamide, sold as Trusopt, is a topical carbonic anhydrase inhibitor eye drop first approved in the United States in 1994 to lower elevated intraocular pressure in glaucoma.
Double eyelids
Double eyelids, also called creased upper eyelids, are upper eyelids with a visible supratarsal crease; about 50% of people of Asian descent lack one, and surgery can create it.
Dream
Dream: spontaneous experiences, mostly visual and emotional, occurring during sleep, most vividly in REM sleep. Key theories include Freud's 1900 psychoanalysis, Hobson and McCarley's 1977 activation-synthesis, and memory-consolidation accounts.
Drusen
Drusen are yellow-white extracellular deposits of the aging retina, the hallmark of age-related macular degeneration; hard, soft, and reticular pseudodrusen (subretinal drusenoid deposits) differ in location, size, and progression risk.
Dual consciousness
Dual consciousness: the hypothesis that one person can contain two conscious subjects, tested mainly in split-brain (callosotomy) patients, where evidence remains divided between two-agents and single-agent split-perception models.
Dura mater
Dura mater (hard mother, pachymeninx): tough outermost meninx of brain and spinal cord, with cranial periosteal and meningeal layers forming venous sinuses and folds like the falx cerebri and tentorium.
Dysautonomia
Dysautonomia, also called autonomic dysfunction or autonomic neuropathy, is an umbrella term for disorders of the autonomic nervous system, covering POTS, pure autonomic failure, familial dysautonomia, and secondary forms from diabetes or Parkinson disease.
Eales disease
Eales disease, first described by Henry Eales in 1880, is an idiopathic occlusive retinal perivasculitis of young men causing neovascularization and recurrent vitreous hemorrhage, linked to tuberculosis, treated with steroids, laser, and vitrectomy.
Ear canal
Ear canal (external auditory canal, external acoustic meatus): the tube from the outer ear opening to the eardrum. Resonates at 2–4 kHz, forms from a meatal plug canalizing at 28–32 weeks, prone to exostoses in cold-water surfers.
Eardrum
Eardrum (tympanic membrane): thin circular tissue about 1 cm wide separating outer and middle ear, vibrating to transmit sound to the ossicles. Three-layered, derived from all germ layers; about 80% of perforations heal spontaneously.
Earlobe
Earlobe (lobule): the soft, cartilage-free lower part of the external ear made of fibrofatty tissue; pierced commonly, elongates with age, polygenic attached-versus-free attachment, site of Frank's sign.
Early age-related macular degeneration
Early age-related macular degeneration (early AMD, ICD-11 9B75.00, AREDS category 2) is the AMD stage defined by medium drusen 63–125 µm without pigmentary abnormalities, asymptomatic, low progression risk, no treatment.
Early-onset Alzheimer's disease
Early-onset (younger-onset) Alzheimer's disease is Alzheimer's beginning before age 65, about 5% of US cases. Familial forms come from APP, PSEN1, and PSEN2 mutations; lecanemab and donanemab modestly slow early symptomatic disease.
Early-onset cerebellar ataxia with retained tendon reflexes
Early-onset cerebellar ataxia with retained tendon reflexes, also called EOCARR or Harding ataxia, is a rare inherited ataxia starting in childhood that resembles Friedreich ataxia but keeps brisk tendon reflexes.
Earwax
Earwax, or cerumen, is the waxy secretion of ear canal glands that protects and cleans the ear. Wet and dry types follow the ABCC11 gene; impaction affects up to 30% of people and is treated with softeners, irrigation, or manual removal.
Ectropion of eyelid
Ectropion of the eyelid: outward turning of the eyelid margin, usually the lower lid, exposing the inner surface. Main types involutional, cicatricial, mechanical, paralytic; treated with lubricants and lateral tarsal strip surgery.
Edaravone (エダラボン)
Edaravone (エダラボン; Radicut/Radicava) is a free-radical scavenging drug approved in Japan (2001) for acute ischemic stroke and in the US (2017 IV, 2022 oral) to slow decline in ALS, one of three FDA-approved ALS drugs.
Edinger–Westphal nucleus
The Edinger–Westphal nucleus (E-W nucleus), described by Edinger in 1885 and Westphal in 1887, is a midbrain cell group whose preganglionic neurons control pupil constriction and lens accommodation.
EEGLAB
EEGLAB is an open-source MATLAB toolbox for single-trial EEG analysis with ICA, first released April 23, 2001 by Delorme and Makeig at UCSD's Swartz Center; about 120 plugins, Octave support, and Python bridges via EEGPrep.
Eigengrau
Eigengrau (Eigenlicht, dark light, brain gray) is the intrinsic dark gray seen in total darkness, a term credited to Gustav Fechner, caused by spontaneous retinal dark noise from visual pigment and phototransduction fluctuations.
Elaine Esposito
Elaine Esposito (1934-1978), the "sleeping beauty," fell into a coma aged six during a 1941 Chicago appendectomy and never woke, holding the Guinness longest-coma record at 37 years 111 days until her death in Florida.
Electrical synapse
Electrical synapse (gap junction synapse): a neuron-to-neuron junction transmitting ionic current directly through connexin channels, mainly Cx36; fast, bidirectional, plastic, and about 20% of connections in C. elegans and rabbit retina circuits.
Electrocorticography
Electrocorticography (ECoG) records brain electrical activity from electrodes on the cortical surface, used in epilepsy surgery and brain-computer interfaces; micro-ECoG arrays reach sub-millimeter resolution.
Electrodiagnosis
Electrodiagnosis (EDX medicine) evaluates nerve, muscle, and neuromuscular junction disorders via nerve conduction studies and needle EMG; distinct from EEG and ECG, it grew from Galvani's frog experiments and WWII nerve-injury studies.
Electroencephalography
Electroencephalography (EEG) records the brain's electrical activity via scalp electrodes. Pioneered by Hans Berger in 1924, it offers millisecond temporal resolution and is the cornerstone test for diagnosing epilepsy and sleep disorders.
Electroencephalography Phase Synchronization
Electroencephalography phase synchronization (EEG phase synchrony) is the uniform alignment of oscillation phases between neuronal groups in EEG, quantified by metrics such as the phase locking value, PLI, and wPLI, and read as a sign of brain integration in learning, memory, and perception.
Electromyography
Electromyography (EMG), an electrodiagnostic test recording muscle electrical activity at rest and during contraction, usually paired with nerve conduction studies to diagnose nerve and muscle disorders such as carpal tunnel syndrome and ALS.
Emmetropia
Emmetropia, from Greek emmetros, is the normal refractive state of the eye: parallel rays focus on the relaxed retina, far point at infinity, opposite of ametropia, reached via emmetropization.