1,240 articles
Medium spiny neuron
Medium spiny neuron (MSN, spiny projection neuron): inhibitory GABAergic projection neuron of the striatum, about 95% of striatal neurons; D1 direct-pathway and D2 indirect-pathway subtypes; lost in Huntington disease.
Medulla oblongata
The medulla oblongata is the lowermost part of the brainstem, continuous with the spinal cord, which controls breathing, heart rate, and blood pressure and houses nuclei for cranial nerves IX through XII.
Medulloblastoma
Medulloblastoma is a grade 4 malignant embryonal brain tumor of the posterior fossa cerebellum, occurring mostly in children, classified into WNT, SHH, group 3, and group 4 molecular subgroups, treated with surgery, craniospinal radiation, and chemotherapy.
Meibomian gland
Meibomian gland (tarsal gland): large modified sebaceous gland in the eyelid tarsal plate, described by Heinrich Meibom in 1666, secreting meibum holocrinely to form the tear film's lipid layer; its dysfunction (MGD) causes most evaporative dry eye.
Melanin-concentrating hormone
Melanin-concentrating hormone (MCH) is a cyclic neuropeptide produced mainly in the hypothalamus that regulates feeding behavior, metabolism, and sleep-wake rhythms, and is a target for obesity drugs.
Melanoma and neural system tumor syndrome
Melanoma and neural system tumor syndrome (melanoma-astrocytoma syndrome, ORPHA:252206, OMIM 155755) is an extremely rare autosomal dominant CDKN2A (9p21.3) predisposition syndrome combining cutaneous melanoma and neural tumors, typically astrocytoma.
Membrane potential
Membrane potential (Vmem, transmembrane voltage) is the inside-minus-outside voltage across a cell membrane, set mainly by K+ permeability and ion gradients, described by Nernst and Goldman-Hodgkin-Katz equations, measured by patch clamp and voltage imaging.
Ménière's disease
Ménière's disease, an inner ear disorder with episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness, linked to endolymphatic hydrops; cause unknown, treated with diet, drugs, injections, or surgery.
Meninges
Meninges: the dura mater, arachnoid mater, and pia mater, the three membranes covering the brain and spinal cord, with their spaces, CSF, blood supply, and related conditions like meningitis and hematomas.
Meningioma
Meningioma, the most common primary brain tumor (37.6% of adult intracranial tumors), a slow-growing tumor of the meninges graded WHO 1-3, with TERT/CDKN2A/B molecular grading and treatment by observation, surgery, or radiosurgery.
Meralgia paraesthetica
Meralgia paraesthetica (Bernhardt-Roth syndrome), lateral femoral cutaneous nerve entrapment causing burning, tingling anterolateral thigh pain without motor loss; risk factors obesity, pregnancy, diabetes, tight clothing; treated conservatively first.
Merkel cell
Merkel cell (Tastzelle), an epidermal mechanosensory cell in the basal skin layer, forming the Merkel cell-neurite complex with Aβ SA1 fibers for light touch; PIEZO2-dependent, ATOH1-specified, epidermal origin; linked to Merkel cell carcinoma.
Mesolimbic pathway
Mesolimbic pathway: dopamine projection from the ventral tegmental area to limbic structures, chiefly the nucleus accumbens. Central to reward, incentive salience ('wanting'), prediction error learning, addiction, depression, and schizophrenia research.
Metachromatic leukodystrophy
Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal storage disease caused by ARSA mutations and arylsulfatase A deficiency, causing sulfatide buildup and demyelination; late-infantile, juvenile, and adult forms; treated with Lenmeldy gene therapy.
Miami Project to Cure Paralysis
Miami Project to Cure Paralysis: spinal cord injury research center at University of Miami Miller School of Medicine, founded 1985 by Barth Green and Nick Buoniconti after Marc Buoniconti's injury; Buoniconti Fund has raised over $550 million; housed in Lois Pope LIFE Center; hypothermia and Schwann cell trials.
Microcephaly
Microcephaly: head circumference more than 2 SD below the mean for age and sex, from genetic, infectious (TORCH, Zika), or environmental causes; no cure, supportive therapy only.
Microelectrode array
A microelectrode array (MEA), or multielectrode array, is a device with many microelectrodes on one substrate that record or stimulate neurons, in cell cultures or implanted in living tissue.
Microglia
Microglia are the resident macrophages and innate immune cells of the CNS parenchyma, discovered by Pío del Río-Hortega in 1918, of yolk sac origin, about 10–15% of glial cells, with diverse disease-associated states beyond the obsolete M1/M2 scheme.
Microtia
Microtia is a congenital underdevelopment of the external ear, ranging from a small malformed auricle to anotia; about 1 in 3,800 US births, usually unilateral, treated by rib cartilage or porous polyethylene reconstruction and bone conduction hearing devices.
Midbrain
Midbrain (mesencephalon): the rostral brainstem segment between diencephalon and pons, divided into tectum and tegmentum, containing the substantia nigra, VTA, colliculi, and cerebral aqueduct; central to Parkinson's disease research and organoid models.
Middle ear
The middle ear (tympanic cavity) is the air-filled space behind the eardrum holding the malleus, incus, and stapes, which transmit and amplify sound to the inner ear, ventilated by the eustachian tube.
Middle ear neuroendocrine tumor
Middle ear neuroendocrine tumor (MeNET), formerly called middle ear adenoma, is a rare tumor of the middle ear causing hearing loss and tinnitus, treated by surgical excision.
Middle Ear Ventilation
Middle ear ventilation, also called tympanostomy or grommet insertion, treats glue ear by inserting tiny tubes through the eardrum to drain fluid and let air in.
Mills syndrome
Mills syndrome is a rare, acquired motor neuron disease marked by slowly progressive spastic hemiparesis on one side of the body with no sensory loss, first described in 1900.
Mind uploading
Mind uploading, also called whole brain emulation, is a proposed process for copying a person's memories, personality, and mental attributes from their biological brain onto a computer.
Minimally conscious state
Minimally conscious state (MCS), ICD-11 8E22, is a disorder of consciousness after severe brain injury with definite but inconsistent signs of awareness, defined by 2002 Aspen Workgroup criteria, assessed with the CRS-R, and prone to about 40% misdiagnosis.
Minimally conscious state minus
Minimally conscious state minus (MCS−, ICD-11 8E22.1) is a disorder-of-consciousness subtype with non-language signs of awareness such as visual pursuit or object manipulation, but no command following or language function; proposed 2011, worse prognosis than MCS+.
Minimally conscious state plus
Minimally conscious state plus (MCS+, ICD-11 8E22.0) is a subdivision of the minimally conscious state defined by preserved language behaviors such as command following, intelligible verbalization, or intentional communication, distinguishing it from MCS minus and predicting faster emergence.
Mirror neuron
Mirror neurons, discovered by Rizzolatti's Parma group in macaque area F5, fire both when an animal performs and observes an action; their proposed role in action understanding is heavily contested.
Mirror-touch synesthesia
Mirror-touch synesthesia is a synesthesia variant in which seeing another person touched produces a felt touch on one's own body; prevalence about 1.6%, explained by threshold and self-other theories, and linked variably to empathy.