1,240 articles
2045 Initiative
2045 Initiative (Россия 2045), transhumanist project founded February 2011 by Russian entrepreneur Dmitry Itskov in Moscow; Avatar A–D roadmap to mind uploading and cybernetic immortality by 2045, disputed by neuroscientists and behind schedule.
5-HT1A receptor
5-HT1A receptor: inhibitory Gi/o-coupled serotonin GPCR acting as raphe autoreceptor and postsynaptic heteroreceptor; target of buspirone, gepirone, vilazodone, and WAY-100635 in anxiety and depression research.
661W
661W is an immortalized mouse cone photoreceptor-like cell line cloned from retinal tumors, the most widely used cell model for retinal disease research, drug screening, and gene therapy development.
Abdominal Reflex
Abdominal reflex: superficial cutaneous reflex (T6-T12) in which stroking the abdominal wall contracts the abdominal muscles, pulling the umbilicus toward the stimulus; absent in about 20% of normal people, lost with thoracic cord or corticospinal tract lesions.
Abducens nerve
The abducens nerve (CN VI), also called the sixth cranial nerve, is a purely motor cranial nerve from the pons that supplies the lateral rectus muscle, abducting the eye.
Abnormal neuronal migration
Abnormal neuronal migration (ICD-11 LA05.5, neuronal migration disorders): failure of fetal neurons to reach correct cortical positions, causing lissencephaly, heterotopia, polymicrogyria, and cortical dysplasia with epilepsy; key genes LIS1, DCX, FLNA, TUBA1A.
Abnormal posturing
Abnormal posturing: decorticate (flexor) and decerebrate (extensor) reflex postures in coma, first described by Sherrington in 1898, scored on the GCS motor scale, indicating severe brain or brainstem injury with poor survival.
Accessory nerve
Accessory nerve (CN XI, spinal accessory nerve), a mostly motor cranial nerve named for Thomas Willis, innervates the sternocleidomastoid and trapezius, exits via the jugular foramen, and is injured mainly during neck surgery, causing shoulder dysfunction.
Accommodation reflex
Accommodation reflex (near response, near triad): a three-part reflex for near vision, lens thickening via ciliary muscle, pupillary constriction, and convergence, mediated by the Edinger-Westphal nucleus, oculomotor nerve, and ciliary ganglion.
Acetylcholine
Acetylcholine (ACh), the first neurotransmitter identified, is a choline ester acting at nicotinic ion-channel and muscarinic GPCR receptors in CNS, autonomic, and neuromuscular synapses; degraded by acetylcholinesterase; central to Alzheimer's and schizophrenia drug development.
Acetylcholine receptor
Acetylcholine receptor: cell-surface proteins activated by acetylcholine, divided into ionotropic nicotinic and G-protein-coupled muscarinic (M1-M5) receptors; targets of nicotine, myasthenia gravis antibodies, and the 2024 antipsychotic KarXT.
Achromatopsia
Achromatopsia (ACHM, rod monochromatism, total color blindness) is a rare autosomal recessive retinal disorder of cone photoreceptors causing color blindness, low acuity, photophobia, and nystagmus; mainly caused by CNGA3 and CNGB3 variants, with gene therapy trials underway.
Acoustic reflex
Acoustic reflex: involuntary stapedius (and tensor tympani) contraction to loud sound, measured as thresholds of 85-100 dB SPL at 500-2000 Hz; used to diagnose middle-ear, cochlear, and retrocochlear disorders.
Acquired stenosis of external auditory canal
Acquired stenosis of external auditory canal (ICD-11 AA40.1): post-inflammatory, postsurgical, post-traumatic, or radiation narrowing of the ear canal lateral to the tympanic membrane, causing otorrhea and conductive hearing loss; treated surgically, with restenosis the main complication.
Acta neuropathologica
Acta neuropathologica (Acta Neuropathol) is a Springer peer-reviewed neuropathology journal founded in 1961 in Berlin, ISSN 0001-6322, organ of the World Federation of Neurology's neuropathology commissions, hybrid model, 2025 impact factor 10.3, with open-access sister journal Acta Neuropathologica Communications (2013).
Acute atopic conjunctivitis
Acute atopic conjunctivitis (ICD-10 H10.1, ICD-11 9A60.01; Angelucci's syndrome, spring catarrh) is a sudden IgE-mediated allergic inflammation of the conjunctiva from airborne allergens, causing itchy, red, watery eyes, usually self-limiting and treated with topical antihistamines.
Acute epidemic conjunctivitis
Acute epidemic conjunctivitis: outbreak form of highly contagious pink eye, mainly adenoviral (EKC serotypes 8, 19, 37; PCF 3, 4, 7) or enteroviral (AHC, EV70, CA24v), self-limited, supportive care.
Acute flaccid myelitis
Acute flaccid myelitis (AFM), a polio-like spinal cord gray matter condition causing sudden limb weakness mainly in young children; linked to enterovirus D68, with US outbreaks in 2014, 2016, and 2018.
Acute macular neuroretinopathy
Acute macular neuroretinopathy (AMN) is a rare retinal disorder causing sudden blind spots near central vision, with reddish-brown wedge-shaped lesions around the fovea, first described in 1975.
Acute mastoiditis
Acute mastoiditis (ICD-11 AB11.0) is a rapid-onset bacterial infection of the mastoid air cells behind the ear, usually complicating acute otitis media in young children; treated with IV antibiotics, myringotomy, or mastoidectomy.
Acute myringitis
Acute myringitis is a recent-onset inflammation of the tympanic membrane, or eardrum, either in the membrane itself or secondary to adjacent external or middle ear inflammation.
Acute otitis media
Acute otitis media (AOM), middle ear infection, acute middle ear infection: rapid-onset infection with middle ear effusion in young children, causing ear pain and fever; most cases resolve in about 3 days without antibiotics, which give small benefits and cause adverse events.
Acute suppurative otitis media
Acute suppurative otitis media is a rapid-onset middle ear infection behind the eardrum that produces pus, mainly affecting young children and often improving within 3 days without antibiotics.
Adrenergic neuron
Adrenergic neuron: neuron whose primary neurotransmitter is epinephrine (adrenaline); noradrenergic neurons use norepinephrine. Includes postganglionic sympathetic fibers and brainstem C1/C2 and A1/A2/A6 cell groups with α2 autoreceptor feedback.
Adult neurogenesis
Adult neurogenesis is the production of functional new neurons in the adult brain, occurring mainly in the hippocampus and debated for humans, with recent single-cell studies finding progenitors.
Adult-onset foveomacular vitelliform dystrophy
Adult-onset foveomacular vitelliform dystrophy (AOFVD, Gass disease, pseudo-Best disease) is a rare macular pattern dystrophy with a yellow egg-yolk-like foveal lesion, adult onset, mostly sporadic inheritance, and slow vision loss.
Afferent nerve fiber
Afferent nerve fiber: sensory axons (also called afferent neurons, dorsal root fibers) carrying information from receptors to the CNS via dorsal roots; classified Aα, Aβ, Aδ, C or Lloyd groups I–IV by conduction velocity.
After-cataract
After-cataract, or posterior capsule opacification (PCO, ICD-11 9B10.22), is the most common complication of cataract surgery: residual lens epithelial cells cloud the posterior capsule, treated by outpatient Nd:YAG laser capsulotomy.
Afterimage
Afterimage: a visual illusion in which an image persists after the stimulus is removed; positive (same color) or negative (complementary color) forms, retinal and cortical mechanisms, Emmert's law, and clinical afterimage testing.
Age and health concerns about Donald Trump
Age and health concerns about Donald Trump: the oldest inaugurated U.S. president (80 in 2026), his White House physicals, chronic venous insufficiency, hand bruising, Montreal Cognitive Assessment claims rated False by PolitiFact, and disputed physician disclosures.