1,240 articles
Long-term depression
Long-term depression (LTD) is a long-lasting weakening of synaptic transmission induced by prolonged low-frequency stimulation, mainly via AMPA receptor internalization; key forms are NMDAR-dependent and mGluR-dependent LTD, studied in hippocampus and cerebellum.
Long-term potentiation
Long-term potentiation (LTP), originally called long-lasting potentiation, is a long-lasting increase in synaptic strength after brief high-frequency stimulation, first reported by Bliss and Lømo in 1973.
Looking
Looking is pointing the eyes toward a location via fixation or smooth pursuit, distinct from covert attention. Covers saccades (20–30 ms), fixations (200–500 ms), gaze following, and eye-tracking methods.
Lower motor neuron
Lower motor neuron: the cholinergic neurons of the spinal cord ventral horn and brainstem motor nuclei whose axons innervate skeletal muscle; Sherrington's final common pathway, forming motor units, with flaccid weakness, hyporeflexia, fasciculations, and atrophy when damaged.
Lugaro cell
Lugaro cell, or fusiform cell of Lugaro: a GABAergic/glycinergic inhibitory interneuron of the cerebellar cortex, first described by Ernesto Lugaro in 1894 in cat; fusiform soma under the Purkinje cell layer, inhibits Golgi and molecular layer interneurons.
Lumbago with sciatica
Lumbago with sciatica (ICD-11 ME84.20) is low back pain with radiating leg pain, historically called sciatica; usually caused by lumbar disc herniation, now preferably termed radicular pain or radiculopathy.
Lumbar nerves
Lumbar nerves: five pairs of mixed spinal nerves L1-L5 exiting below their vertebrae, dividing into dorsal and ventral rami, forming the lumbar plexus (T12-L4) and, via the lumbosacral trunk, the sacral plexus.
Lumbar plexus
Lumbar plexus: somatic nerve network from L1-L4 ventral rami (often with T12 subcostal contribution) lying within psoas major; six branches including femoral and obturator nerves; mean variation prevalence 20.1%.
LX101, RPE65 AAV gene therapy for inherited retinal dystrophy
LX101 (LX-101), Innostellar Biotherapeutics' rAAV2-RPE65 subretinal gene therapy for biallelic RPE65 mutation-associated inherited retinal dystrophy; phase 3 STAR trial in China, commercialization rights held by Golden Age Health.
Lysosomal storage disease
Lysosomal storage diseases (LSDs, lysosomal storage disorders): over 70 inherited metabolic disorders caused by defective lysosomal enzymes or transporters; treated mainly by enzyme replacement therapy since 1991 (Gaucher disease).
Lytico-bodig disease
Lytico-bodig disease, also called ALS/PDC or Guam disease, is a neurodegenerative ALS-parkinsonism-dementia syndrome endemic to the Chamorro people of Guam, peaking in the 1950s and linked to the cycad toxin BMAA hypothesis.
M cone cell
M cone cell (medium-wavelength-sensitive cone, OPN1MW, green cone): retinal photoreceptor peaking near 543 nm, one of three cone classes enabling human trichromatic vision; X-linked gene, deutan color blindness, olo M-only stimulation.
Macrotia
Macrotia is an abnormally large external ear, defined by ear length and width more than 2 standard deviations above age- and sex-specific means, classified as a minor anomaly of the pinna.
Macular disorders
Macular disorders (ICD-11 9B75, 黄斑障害) are diseases of the macula, the retina's central vision area. They include age-related macular degeneration, macular edema, macular hole, and inherited macular dystrophies, staged by drusen size and treated with anti-VEGF drugs.
Macular edema
Macular edema is fluid accumulation in the macula, the central retina, caused by blood-retinal barrier dysfunction in diabetes, retinal vein occlusion, uveitis, and post-cataract inflammation; treated with anti-VEGF drugs, corticosteroids, and laser.
Madras motor neuron disease
Madras motor neuron disease (MMND) is a rare motor neuron disorder first described in 1970 in Chennai, India, with young onset, distal limb wasting, lower cranial nerve palsies, pyramidal signs, and sensorineural deafness; a variant adds optic atrophy.
Magnetic resonance imaging of the brain
Brain MRI (head MRI) images the brain using a strong magnet, radio waves, and a computer without ionizing radiation. Field strengths of 1.5, 3, and 7 tesla; gadolinium contrast; used for stroke, tumors, and multiple sclerosis.
Magnetoencephalography
Magnetoencephalography (MEG) is a non-invasive brain imaging method recording neuromagnetic fields with SQUID or optically pumped magnetometer sensors, offering millimeter spatial and millisecond temporal resolution for epilepsy localization and presurgical mapping.
Mal de debarquement
Mal de debarquement (MdD) is the rocking or swaying self-motion sensation after passive motion like sea travel; when persistent it is mal de debarquement syndrome (MdDS), a rare female-predominant vestibular disorder with Bárány Society diagnostic criteria and optokinetic stimulation as leading treatment.
Mandibular nerve
Mandibular nerve (CN V3, nervus mandibularis), largest trigeminal division and the only one with a motor root; exits via foramen ovale, splits into anterior and posterior divisions, supplies mastication muscles, lower teeth, tongue, and is the target of the inferior alveolar nerve block.
Manganese poisoning
Manganese poisoning, also called manganism, is a neurological condition caused by chronic inhalation of manganese dust or fumes, producing tremor, rigidity, slowed movement, and psychiatric disturbance.
Martin Pistorius
Martin Pistorius (born 1975, Johannesburg), author of the memoir Ghost Boy, fell into an unexplained locked-in state at age 12 in 1988; aware but unable to move or speak for about 10 years, he communicated via eye-movement computer software from 2001 and now works in assistive technology.
Martinique crinkled retinal pigment epitheliopathy
Martinique crinkled retinal pigment epitheliopathy (MCRPE, MDPT3, patterned macular dystrophy 3) is an ultra-rare autosomal dominant retinal dystrophy from MAPKAPK3 mutations, first described in Martinique, with a dry-desert-land fundus pattern, adult onset, and PCV or CNV complications.
Mastoiditis
Mastoiditis is a bacterial infection of the mastoid air cells, usually complicating acute otitis media in young children. Key signs are postauricular swelling with pinna displacement; treated with IV ceftriaxone, sometimes mastoidectomy.
Maternal bond
Maternal bond: the mother's emotional connection to her child, distinct from infant attachment. Measured by tools like the Postpartum Bonding Questionnaire; rooted in oxytocin and dopamine systems; disrupted by postpartum depression.
Mauthner neuron
Mauthner neuron (Mauthner cell, M-cell): a pair of giant reticulospinal hindbrain neurons in fishes and amphibians that triggers the C-start escape response, with ~100 μm somata, segregated sensory dendrites, and mixed electrical-chemical synapses.
Maxillary nerve
Maxillary nerve (V2), middle purely sensory division of the trigeminal nerve; exits via foramen rotundum to the pterygopalatine fossa, ends as the infraorbital nerve, and supplies midface, upper teeth, palate, and nasal mucosa.
Mechanical lagophthalmos
Mechanical lagophthalmos is incomplete eyelid closure caused by physical obstruction such as proptosis, scarring, ectropion, or symblepharon, distinct from paralytic lagophthalmos; ICD-10 code H02.22, treated with lubricants, taping, tarsorrhaphy, and scar release.
Mechanoreceptor
Mechanoreceptors are sensory receptors converting touch, pressure, vibration, and stretch into neural signals. Key cutaneous types include Merkel, Meissner, Pacinian, and Ruffini receptors, with PIEZO2 as the principal mechanotransducer ion channel.
Median nerve
Median nerve: terminal branch of the brachial plexus (lateral and medial cords, C5-T1) innervating most forearm flexors, thenar muscles, and the lateral 3.5 digits; compressed in carpal tunnel and pronator syndrome.