1,240 articles
Progressive pseudobulbar palsy
Progressive pseudobulbar palsy (ICD-11 8B60.2) is a motor neuron disease from bilateral corticobulbar tract degeneration, causing spastic dysarthria, dysphagia, and pseudobulbar affect without tongue wasting, distinct from progressive bulbar palsy.
Progressive supranuclear palsy
Progressive supranuclear palsy (PSP), or Steele-Richardson-Olszewski syndrome, is a rare 4-repeat tau neurodegenerative disease causing vertical gaze palsy, backward falls, and dementia, beginning around age 65 with severe disability within 3 to 5 years.
Proliferative diabetic retinopathy
Proliferative diabetic retinopathy (PDR), also called retinitis proliferans, is the advanced neovascular stage of diabetic retinopathy and a leading cause of working-age blindness; treated with panretinal photocoagulation, anti-VEGF injections, or vitrectomy.
Proliferative vitreoretinopathy
Proliferative vitreoretinopathy (PVR), also called massive periretinal proliferation, is a fibroproliferative complication of retinal detachment in which contractile membranes cause tractional redetachment; it affects 5–10% of RRD cases and has no approved drug therapy.
Proprioception
Proprioception (Sherrington's term, 1906) is the body-position, movement, and force sense from muscle spindles, Golgi tendon organs, joint, and skin receptors; tested by TTDPM, JPR, AMEDA, and trainable for sport.
Protruding ear
Protruding ear, also called prominent or bat ear, is a congenital auricular deformity with over 2 cm projection or auriculocephalic angle over 25 degrees, affecting about 5% of people, treated by infant ear molding or otoplasty.
Psychological research
Psychological Research is a peer-reviewed journal published by Springer, covering human perception, attention, memory, and action. Founded in 1922 as Psychologische Forschung, it became an English-language international journal in 1974.
Psychoneuroendocrinology
Psychoneuroendocrinology (PNE) is an interdisciplinary field linking psychology, endocrinology, immunology, neurology, and psychiatry, studying hormone-brain-behavior interactions; ISPNE founded 1975 with its journal Psychoneuroendocrinology.
Psychoneuroimmunology
Psychoneuroimmunology (PNI), also called psycho-neuro-immunology, studies bidirectional interactions among behavior, nervous and endocrine function, and immunity; founded on Ader and Cohen's 1975 conditioned immunosuppression, spanning stress effects on infection to inflammation in depression.
Pterygium
Pterygium (surfer's eye) is a benign wing-shaped fibrovascular growth of conjunctiva onto the cornea, driven by UV exposure, affecting about 8% of people globally, treated by excision with conjunctival autograft.
Ptosis (eyelid)
Ptosis (blepharoptosis) is drooping of the upper eyelid margin, classified as aponeurotic, myogenic, neurogenic, or mechanical. Treated mainly by surgery; oxymetazoline 0.1% is the only FDA-approved drug for adults.
Pudendal nerve
Pudendal nerve (Alcock's canal nerve), paired S2–S4 sacral plexus nerve supplying perineum, genital sensation, and anal and urethral sphincters; compression causes pudendal neuralgia, diagnosed by Nantes criteria and treated with blocks, stimulation, or decompression.
Pulsed electromagnetic field therapy
Pulsed electromagnetic field (PEMF) therapy, also called pulsed electromagnetic field stimulation, is a noninvasive treatment using coil-generated magnetic fields to induce healing currents in bone; FDA first approved it in 1979 for fracture nonunions, with mixed evidence in osteoarthritis and pain.
Pupil
Pupil (pupilla): the central aperture of the iris through which light enters the eye. Size is set by parasympathetic sphincter pupillae constriction and sympathetic dilator pupillae dilation; measured by pupillometry.
Pupillary light reflex
Pupillary light reflex (PLR): involuntary pupil constriction to light via retina, optic nerve (CN II), pretectal area, Edinger-Westphal nucleus, CN III, ciliary ganglion; tested by swinging flashlight test for RAPD.
Purkinje cell
Purkinje cell: large GABAergic neuron of the cerebellar cortex, discovered by Jan Evangelista Purkyně in 1837; sole output of cerebellar cortex, inhibiting deep cerebellar nuclei and mediating motor learning plasticity.
Pvalb chandelier GABAergic interneuron
Pvalb chandelier GABAergic interneuron, also called chandelier cell or axo-axonic cell, is a fast-spiking parvalbumin interneuron whose cartridge boutons exclusively target pyramidal axon initial segments, with links to epilepsy, schizophrenia, and autism.
Pyramidal cell
Pyramidal cell (pyramidal neuron): excitatory projection neuron of the cerebral cortex and hippocampus with pyramid-shaped soma, apical dendrite toward the pial surface, spiny dendrites, and a base-originating axon; the most common cortical neuron.
Pyramidal tracts
Pyramidal tracts: cortical motor fiber systems (corticospinal and corticobulbar tracts) passing through the medullary pyramids; about 75-90% decussate, controlling voluntary movement, with lesions causing contralateral weakness.
Quinpirole
Quinpirole (LY 171555) is a pyrazoloquinoline compound acting as a full agonist at dopamine D2 and D3 receptors, used in research as the reference full agonist.
Radial glial cell
Radial glial cell (RGC), embryonic neural stem cell spanning ventricle to pia; primary progenitor generating cortical neurons and glia and scaffold for neuronal migration; transforms into astrocytes after neurogenesis.
Radial nerve
Radial nerve: C5–T1 terminal branch of the brachial plexus posterior cord, supplying arm and forearm extensors and dorsal hand sensation; injuries cause wrist drop, Saturday night palsy, and Wartenberg's syndrome.
Radiation myelitis
Radiation myelitis, or radiation-induced myelopathy, is spinal cord injury from radiotherapy, spanning transient Lhermitte's-sign myelopathy and chronic progressive myelitis; risk is dose- and fractionation-dependent, rising sharply above 50 Gy.
Radiculopathy
Radiculopathy, also called radiculitis or nerve root disorder, is pain, numbness, tingling, and weakness from a compressed spinal nerve root; types are cervical, thoracic, and lumbar, most often caused by disc herniation.
Ralph W. Gerard Prize in Neuroscience
Ralph W. Gerard Prize in Neuroscience: the Society for Neuroscience's highest honor, a lifetime-achievement award named for SfN founder Ralph Waldo Gerard (1900–1974); recent recipients include Joshua Sanes (2025) and Nora D. Volkow (2024).
Randy Gardner sleep deprivation experiment
The Randy Gardner sleep deprivation experiment kept 17-year-old Randy Gardner of San Diego awake for a record 264 hours in 1963–1964, as a school science fair project.
Rapid eye movement sleep
Rapid eye movement (REM) sleep, also called paradoxical sleep, is a sleep state with activated EEG, rapid eye movements, and muscle atonia, discovered by Aserinsky and Kleitman in 1953, generated by a pontine flip-flop switch, and linked to vivid dreaming and REM behavior disorder.
Rapid eye movement sleep behavior disorder
REM sleep behaviour disorder (RBD, REM sleep behavior disorder) is a parasomnia with loss of REM atonia and dream enactment; about 80% of isolated cases convert to synucleinopathy within 10 years; treated with clonazepam, melatonin, pramipexole, or rivastigmine.
Rasagiline
Rasagiline (Azilect) is a selective, irreversible MAO-B inhibitor drug approved for Parkinson's disease, first approved in Israel and Europe in 2005 and by the US FDA in 2006.
Recurrent idiopathic neuroretinitis
Recurrent idiopathic neuroretinitis (RINR), a rare inflammatory optic neuropathy with recurrent painless visual loss, optic disc edema, and macular star; poor prognosis, treated with long-term azathioprine and prednisone.