| neural layer of retina | The internal layer of the retina containing the neural elements, as distinguished from the outer leaf of the retina, or pigmented layer. Synonym: pars optica retinae, neural layer of retina, optic part of retina, stratum cerebrale retinae. (05 Mar 2000) |
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| neural networks | A computer architecture, implementable in either hardware or software, modeled after biological neural networks. Like the biological system in which the processing capability is a result of the interconnection strengths between arrays of nonlinear processing nodes, computerised neural networks, often called perceptrons or multilayer connectionist models, consist of neuron-like units. A homogeneous group of units makes up a layer. These networks are good at pattern recognition. They are adaptive, performing tasks by example, and thus are better for decision-making than are linear learning machines or cluster analysis. They do not require explicit programming. (04 Jul 1999) |
| neural part of hypophysis | It is composed of the infundibulum and the nervous lobe of hypophysis. See: hypophysis. Synonym: lobus posterior hypophyseos, neural part of hypophysis, pars nervosa hypophyseos, posterior lobe of hypophysis. Origin: neuro-+ hypophysis (05 Mar 2000) |
| neural pathway | <anatomy> Neural tracts connecting one part of the nervous system with another. (12 Dec 1998) |
| neural plate | <embryology> A region of embryonic ectodermal cells, called neuroectoderm, that lie directly above the notochord. During neurulation, they change shape, so as to produce an infolding of the neural plate (the neural fold) that then seals to form the neural tube. (04 Jul 1999) |
| neural retina | <embryology> Layer of nerve cells in the retina, embryologically part of the brain. The incoming light passes through nerve fibres and intermediary nerve cells of the neural retina, before encountering the light sensitive rods and cones at the interface between neural retina and the pigmented retinal epithelium. (04 Jul 1999) |
| neural segment | Alternate swellings and constrictions seen along the neuraxis at early stages of neural tube development, thought to be evidence of intrinsic segmentation in the CNS. Neuromeres or segments in the hindbrain region are called rhombomeres and have been shown to be lineage restriction units, each constructing a defined piece of hindbrain. (18 Nov 1997) |
| neural spine | The middle point of the neural arch of the typical vertebra, represented by the spinous process. (05 Mar 2000) |
| neural tube | <embryology> The progenitor of the central nervous system. See: neural plate, neurulation. (18 Nov 1997) |
| neural tube defect | <neurology, paediatrics> Abnormal development during embryonic life of the neural tube producing congenital malformations of the nervous system due to closure failure of the neural tube. The structure gives rise to the central nervous system (the brain and spinal cord), and failure to close results in anencephaly (absence of the cranial vault and absence of most or all of the cerebral hemispheres of the brain) and spina bifida or meningomyelocele (open spina with exposure and protusion of the spinal cord). The risk of neuroal tube defects can be decreased by the mother taking folic acid during pregnancy. (04 Jul 1999) |
| neuralgia | <symptom> Paroxysmal pain which extends along the course of one or more nerves. Many varieties of neuralgia are distinguished according to the part affected or to the cause, as brachial, facial, occipital, supraorbital, etc. Or anaemic, diabetic, gouty, malarial, syphilitic, etc. (18 Nov 1997) |
| neuralgia facialis vera | A severe paroxysmal lancinating pain deep in the ear, on the anterior wall of the external meatus, and on a small area just in front of the pinna. Synonym: geniculate otalgia, Hunt's neuralgia, neuralgia facialis vera. (05 Mar 2000) |
| neuralgic | Relating to, resembling, or of the character of, neuralgia. (05 Mar 2000) |
| neuralgic amyotrophy | A neurological disorder, of unknown cause, characterised by the sudden onset of severe pain, usually about the shoulder and often beginning at night, soon followed by weakness and wasting of various forequarter muscles, particularly shoulder girdle muscles; both sporadic and familial in occurrence with the former much more common; often preceded by some antecedent event, such as an upper respiratory infection, hospitalization, vaccination, or non-specific trauma; usually attributed to a brachial plexus lesion, because the nerve fibres involed are most often derived from the upper trunk, but actually multiple proximal mononeuropathies. Synonym: acute brachial radiculitis, brachial plexitis, brachial plexus neuropathy, Parsonage-Turner syndrome, shoulder-girdle syndrome. (05 Mar 2000) |
| neuralgiform | Resembling or of the character of neuralgia. (05 Mar 2000) |