1,240 articles
Axon terminal
Axon terminal (presynaptic terminal, terminal bouton): swelling on an axon that releases neurotransmitter via calcium-triggered vesicle fusion at active zones; forms terminal or en passant synapses.
Barotrauma
Barotrauma: tissue injury from pressure differences across gas-filled body spaces during flying, diving, or hyperbaric therapy; ear barotrauma (airplane ear, otic barotrauma) is the most common form.
Basal ganglia
Basal ganglia (basal nuclei): interconnected subcortical brain nuclei (caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra) that modulate voluntary movement via direct and indirect striatal pathways; dysfunction causes Parkinson disease, Huntington disease, and dystonia.
Basilar membrane
Basilar membrane: elastic membrane dividing the cochlea's scala media and scala tympani, carrying the tonotopic traveling wave discovered by von Békésy (Nobel 1961), later shown to be nonlinear and amplified by outer hair cells.
Basket cell
Basket cell: GABAergic inhibitory interneuron forming basket-like axon terminals around pyramidal cell somata and proximal dendrites; two classes, fast-spiking parvalbumin and regular-spiking CCK basket cells, controlling principal cell output and oscillations.
Bates method
Bates method: alternative vision-improvement system by ophthalmologist William H. Bates (Perfect Sight Without Glasses, 1920), using palming, sunning, swinging, and central fixation; rejected by ophthalmology, trials show no refractive improvement, and sungazing risks solar retinopathy.
Batten disease
Batten disease, also called Spielmeyer-Vogt disease or Batten-Mayou syndrome, is the common name for the neuronal ceroid lipofuscinoses, inherited lysosomal storage disorders causing childhood vision loss, seizures, and early death.
Behavioral neuroscience
Behavioral neuroscience, also known as biological psychology or biopsychology, is the branch of neuroscience studying how the nervous system produces behavior, emotions, and mental processes, largely through experiments with laboratory animals.
Bell's palsy
Bell's palsy, or idiopathic facial nerve palsy, is sudden one-sided facial weakness, the most common cause of facial paralysis; steroids within 72 hours help, and most patients recover within 3 to 6 months.
Beta Rhythm
Beta rhythm: EEG brain waves of 15–30 Hz (often 13–30 Hz) seen during wakefulness and mental activity; named by Hans Berger in 1930, low amplitude (10–20 µV), frontal-central, enhanced by sedatives.
Betz cell
Betz cell, giant pyramidal neuron (Riesenpyramide) of layer Vb of the primary motor cortex, described by Volodymyr Betz in 1874; largest cortical neurons, projecting via the corticospinal tract, monosynaptic to spinal motoneurons in primates, absent in rodents, and implicated in ALS.
Bicuculline
Bicuculline is a plant-derived alkaloid isolated in 1933 from Dutchman's breeches that competitively blocks GABAA receptors; a powerful convulsant, it has been the standard pharmacological tool for studying GABA-mediated inhibition since 1970.
Bietti crystalline dystrophy
Bietti crystalline dystrophy (BCD, Bietti crystalline corneoretinal dystrophy) is a rare autosomal recessive retinal disease caused by CYP4V2 mutations, marked by yellow-white retinal crystals, night blindness, and progressive vision loss.
Binaural hearing
Binaural hearing is the brain's use of input from both ears to locate sounds in space, based on differences in arrival time and intensity between the ears.
Binocular rivalry
Binocular rivalry: alternating conscious perception when two different images are shown one to each eye. Also called ocular equivocation; first systematically studied by Wheatstone (1838); key paradigm for consciousness research and interocular suppression.
Binocular vision
Binocular vision, also called binocular fusion, is the use of both eyes together so the brain merges two slightly different retinal images into a single percept with depth.
Biocompatibility
Biocompatibility: the ability of a medical device or material to perform with an appropriate host response in a specific application. Evaluated under ISO 10993-1 and FDA guidance via risk assessment and cytotoxicity, irritation, sensitization, and other endpoint testing.
Biological psychiatry
Biological psychiatry: interdisciplinary science of the biological bases of behavior (biochemical, genetic, physiological, neurological) applied to mental illness; three historical waves, flagship journal Biological Psychiatry (1969), ongoing biomarker and clinical-translation debate.
Bipolar neuron
Bipolar neuron: a nerve cell with one axon and one dendrite extending from opposite poles of the soma; rare sensory neurons of the retina, olfactory epithelium, and inner-ear ganglia.
Bitemporal hemianopsia
Bitemporal hemianopsia (bitemporal hemianopia): loss of the temporal half of the visual field in both eyes, classically from a pituitary adenoma or other lesion compressing crossing nasal fibers at the optic chiasm.
Black eye
Black eye (periorbital hematoma, periorbital ecchymosis): bruising and swelling around the eye from face or head trauma, usually healing in days to 3 weeks; ice, acetaminophen, and checks for hyphema, orbital fracture, or skull fracture.
Blepharoplasty
Blepharoplasty, or eyelid surgery, removes or repositions excess eyelid skin, muscle, and fat for cosmetic or functional reasons. Named by von Graefe in 1818; origins with Susruta; first double-eyelid surgery by Mikamo Nagai in 1896.
Blepharospasm
Blepharospasm, or benign essential blepharospasm, is an adult-onset focal dystonia causing involuntary orbicularis oculi spasms and forced eyelid closure; treated mainly with botulinum toxin injections every 3 to 4 months, with myectomy for refractory cases.
Blind spot (vision)
Blind spot (vision), or physiological blind spot (punctum caecum), is the visual-field gap corresponding to the photoreceptor-free optic disc, about 6° × 7° at 15–16° temporal; discovered by Mariotte in 1668 and normally hidden by filling-in and the fellow eye.
Blindsight
Blindsight: residual visual capacity, such as detecting or locating stimuli, without perceptual awareness after primary visual cortex (V1) damage; coined by Larry Weiskrantz from patient DB studies, supported by LGN and superior colliculus-pulvinar pathways.
Blinking
Blinking: rapid eyelid closing and opening in spontaneous, reflex, and voluntary forms, spreading the tear film at 8–21 blinks per minute, controlled by brainstem and cortical circuits, and modulated by dopamine.
Blood–brain barrier
Blood–brain barrier (BBB): selective endothelial interface of brain capillaries with tight junctions and efflux pumps; blocks over 90% of small-molecule drugs; crossed via GLUT-1, receptor-mediated transcytosis (TfR1, LRP1), or focused ultrasound opening; term coined by Lewandowsky in 1900.
Blue Brain Project
Blue Brain Project: Swiss EPFL brain-simulation initiative led by Henry Markram, 2005–2024, using IBM and HPE supercomputers to digitally reconstruct rat and mouse neocortical microcircuits, culminating in the 2015 31,000-neuron reconstruction and a whole mouse brain model.
Blue field entoptic phenomenon
Blue field entoptic phenomenon, or Scheerer's phenomenon: bright moving dots seen against blue sky, caused by white blood cells passing through macular retinal capillaries; used to measure macular blood flow.
Bombesin
Bombesin is a 14-amino-acid peptide isolated from the skin of the European fire-bellied toad Bombina bombina in 1971 by pharmacologist Vittorio Erspamer, now the standard scaffold for imaging GRP-receptor-expressing tumors.