gray matter

Also found in: Dictionary, Thesaurus, Legal, Acronyms, Idioms, Encyclopedia, Wikipedia.


1. physical material having form and weight under ordinary conditions; called also substance.
2. pus.
gray matter areas of the nervous system where the nerve fibers are unmyelinated (not enveloped by a myelin sheath); it contains the bodies of the nerve cells. Tissue composed of myelinated fibers is called white matter. The cerebral cortex is entirely composed of gray matter and the cerebellum also contains some deep-seated masses of it. The spinal cord has a central core of gray matter surrounded by white matter; in cross section, its gray matter is shaped approximately like the letter H. Called also substantia grisea and gray substance.
white matter areas of the nervous system composed mostly of myelinated nerve fibers (those having myelin sheaths) constituting the conducting portion of the brain and spinal cord. Tissue composed of unmyelinated fibers is called gray matter. Called also substantia alba and white substance.

gray mat·'ter

those regions of the brain and spinal cord that are made up primarily of the cell bodies and dendrites of nerve cells rather than myelinated axons.

gray matter

1. Brownish-gray nerve tissue, especially of the brain and spinal cord, composed of nerve cell bodies and their dendrites and some supportive tissue.
2. Informal Brains; intellect.

gray matter

the gray nervous tissue found in the cortex of the cerebrum and cerebellum and the core of the spinal cord. It is predominantly composed of neuron cell bodies and unmyelinated axons. The gray color is produced by cytoplasmic elements seen in all cell bodies and processes not covered by whitish myelin. Nuclei in the gray substance of the spinal cord function as centers for all spinal reflexes. Also called gray substance. Compare white matter. See also cerebellum, cerebral cortex, cerebrum, spinal cord, spinal nerves.
Nonmyelinated cells and circuitry that comprise the ‘central processing unit’ of the CNS and spinal cord; the thinking part of the brain, which is composed of neuronal cell bodies, initial axon segments, dendritic processes, and arborizations, glia—neuroglial cells—capillaries and vascular support; gray matter is so named because it appears grayish; brain gray matter is peripheral; spinal cord gray matter is central

gray mat·ter

(grā mat'ĕr) [TA]
Those regions of the brain and spinal cord that are made up primarily of the cell bodies and dendrites of nerve cells rather than myelinated axons.
Synonym(s): substantia grisea [TA] , gray substance.

gray matter

gray areas of brain and spinal cord made up primarily of cell bodies and dendrites of nerve cells rather than myelinated axons. White matter or substance is the tissue composed primarily of myelinated, or medullated, fibers.
The bodies of the nerve cells are centered in the gray matter. In the brain the gray matter may be external to white matter, e.g. cerebellum, or central to it, e.g. cerebrum. The cerebral cortex is composed of gray matter and there are some deep-seated nuclei too. In the spinal cord there is a central core of gray matter surrounded by white matter. On a cross-section of the spinal cord the gray matter follows the general pattern of the letter H.
References in periodicals archive ?
Those signs signal gray matter myelitis and spinal cord ischemia, and high-dose corticosteroids can prevent a cord infarct and permanent paraplegia, Dr.
Although the researchers found a negative correlation between gray matter and age in both groups of people -- suggesting a loss of brain tissue with increasing age -- they also found that large parts of the gray matter in the brains of those who meditated seemed to be better preserved, Kurth said.
Since larger gray matter volume may reflect insufficient pruning and maturity of the brain, the negative correlation between the gray matter volume and IQ scores suggests that growing without parental care may delay brain development.
The difference seemed to be driven by a loss of gray matter, Dr.
In particular, thinner gray matter corresponded to better math performance in the higher fit kids.
Gray matter of the brain has been shown to differ in volume as a function of people's experiences.
The findings are also important in showing that markers of proinflammatory cytokines at the baseline assessment predicted the rate of gray matter loss among the individuals who converted to psychosis, suggesting that activation of microglia was involved in the tissue loss," he added.
With more work on the hideous control set-up and more attention to detail, Gray Matter could have been great.
Gray matter is a reddish-brown layer that forms the cortex of the cerebrum and cerebellum.
The scans showed that after 3 months of playing the block-stacking game, gray matter in the girls' brains was thicker.
They then used high-resolution structural magnetic resonance imaging of the brain to measure gray matter volume.
Only the stuff encountered here is more psychologically playful, like a brainstorm of real gray matter and a runaway Train of Thought.