| UM | movement unsharpness; upper motor [neuron]; uracil mustard; utilization management |
|---|---|
| UMN | upper motor neuron |
| UMNL | upper motor neuron lesion |
| UMNS | upper motor neuron syndrome |
| MEP | maximum expiratory pressure; mean effective pressure; mepiridine; mitochondrial encephalopathy; moto... |
| magnocellular neuron | <anatomy, neurology> A neuron in the magnocellular region of the brain. Perhaps the first class of neuron from the central nervous system shown to be sensitive to nerve growth factor (that had previously been thought only to act at the periphery). (18 Nov 1997) |
|---|---|
| Mauthner neuron | <biology, marine biology> Large neuron in the mesencephalon of fishes and amphibians. A rare example of an individually identifiable neuron in a vertebrate nervous system. (18 Nov 1997) |
| cell adhesion molecules, neuron-glia | Cell adhesion molecules that mediate neuron-neuron adhesion and neuron-astrocyte adhesion. They are expressed on neurons and schwann cells, but not astrocytes and are involved in neuronal migration, neurite fasciculation, and outgrowth. Ng-cam is immunologically and structurally distinct from ncam (neural cell adhesion molecules). (12 Dec 1998) |
| Golgi type II neuron | <physiology> Nerve cells with short axons which ramify in the gray matter. (05 Mar 2000) |
| Golgi type I neuron | <physiology> Nerve cells whose long axons leave the gray matter of which they form a part. (05 Mar 2000) |
| cholinergic neuron | <physiology> Neurons in which actylcholine is the neurotransmitter. (15 Jan 1998) |
| piriform neuron layer | The layer of Purkinje cells between the molecular and granular layers of the cerebellar cortex. Synonym: stratum neuronorum piriformium, ganglionic layer of cerebellar cortex, layer of piriform neurons, Purkinje's layer, stratum gangliosum cerebelli. (05 Mar 2000) |
| multipolar neuron | A neuron with several processes, usually an axon and three or more dendrites. (05 Mar 2000) |
| polymorphic neuron | Occurring in many shapes. See: multipolar cell. (05 Mar 2000) |
| pseudounipolar neuron | A neuron whose cell body emits a single axonal process resulting from the fusion of two polar processes during development; at a variable distance from the cell body, the process divides into a peripheral axon branch extending outward as a peripheral afferent (sensory) nerve fibre, and a central axon branch that enters into synaptic contact with neuron's in the spinal cord or brainstem. With the single known exception of the neuron's composing the mesencephalic nucleus of the trigeminus, unipolar neuron's are the exclusive neural elements of the sensory ganglia. The lack of dendritic processes of these primary sensory neuron's is only apparent: the dendritic pole of the unipolar neuron is represented by the unmyelinated terminal ramifications of the peripheral axon branch. Synonym: pseudounipolar cell, pseudounipolar neuron, unipolar cell. (05 Mar 2000) |
| sensory neuron | 1. <anatomy> A neuron that receives input from sensory cells. 2. <physiology> Sensory cells such as cutaneous mechanoreceptors and muscle receptors. (18 Nov 1997) |
| NANC neuron | <abbreviation> Nonadrenergic, noncholinergic neuron. (05 Mar 2000) |
| neuron | An excitable cell specialised for the transmission of electrical signals over long distances. Neurons receive input from sensory cells or other neurons and send output to muscles or other neurons. Neurons with sensory input are called sensory neurons, neurons with muscle outputs are called motoneurons, neurons that connect only with other neurons are called interneurons. Neurons connect with each other via synapses. Neurons can be the longest cells known, a single axon can be several metres in length. Although signals are usually sent via action potentials, some neurons are nonspiking. (18 Nov 1997) |
| nonadrenergic, noncholinergic neuron | Autonomic efferent neuron whose transmission is not blocked by blocking adrenergic and cholinergic transmission. Nitric oxide may be the transmitter in some cases. (05 Mar 2000) |
| nonspiking neuron | <physiology> A neuron that can convey information without generating action potentials. As passive electrical potentials are attenuated over distances greater than the space constant for a neuron (typically 1mm), this implies that most nonspiking neurons are involved in signalling over relatively short distances. Typical examples are invertebrate stretch receptors and interneurons in the central nervous system. (12 Mar 1998) |