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Results for “Gray Matter”

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At least 19 recordsLinked to original sources

PubMed1977

White-gray matter differentiation in computed tomography.

A numerical analysis has been performed on six regions of interest within the brain for a total of 60 patients. Three areas of white matter and three of gray matter were included. A difference of 7.1 +/- 1.3 Hounsfeld units (HU: 1,000 scale) was found between white and gray matter. For eight patients who were under 15 years of age, the difference was 5.1 +/- 0.6 HU. Contrast injection resulted in a general increase of values, with gray matter showing a greater elevation by 0.5 HU. The numerical evaluation of white and gray matter has proven to be useful in the diagnosis of leukoencephalopathy.

Adolescent↗

PubMed1977

White and gray matter of the brain differentiated by computed tomography.

The white and gray matter of the brain can be clearly differentiated by computed tomography (CT). The differentiation is enhanced by the administration of contrast material. Without contrast material, the mean attenuation number of the white matter was 29 units, of the gray matter, 35 units. The effective low contrast resolving power of CT scanners can be clinically evaluated by comparing their ability to differentiate the white and gray matter of the brain.

Brain↗

PubMed2026

Effect of cognitive enhancement therapy for early course schizophrenia on gray matter volume: A confirmatory multisite randomized clinical trial.

BACKGROUND: Cognitive Enhancement Therapy (CET) is an evidence-based cognitive remediation intervention for early course schizophrenia with established benefits for cognition. CET may protect against broad temporolimbic gray matter volume loss associated with cognitive improvement, but this finding has yet to be replicated. This research reexamined if CET protects against temporolimbic gray matter volume loss in an independent and larger multisite early course sample, and if this neuroprotective effect predicts cognitive and social adjustment improvement. METHODS: Ninety-nine participants with early course schizophrenia completed MRI, cognitive, and social adjustment assessments at baseline, 9 (mid-treatment), and 18 (end of treatment) months. Linear mixed-effects models examined the differential impact of CET (n = 56) compared to Enriched Supportive Therapy (n = 43) on temporolimbic gray matter volume in regions-of-interest (ROIs) that previously demonstrated CET-related neuroprotection (primary ROIs), as well as frontotemporal ROIs outlined in the first trial (secondary ROIs). RESULTS: The right rostral anterior cingulate was the only primary ROI to demonstrate a significant group × time interaction, but was unrelated to cognitive and social adjustment change. No secondary ROIs exhibited a differential treatment effect. CONCLUSION: This confirmatory trial did not recapitulate the observed broad pattern of CET-related temporolimbic gray matter volume neuroprotection. Consistent with the larger literature demonstrating limited evidence of cognitive remediation effects on the brain in schizophrenia, these findings underscore the need for continued investigation of CET-related changes with other neuroimaging modalities, especially given its established cognitive benefits. Such information is critical for cognitive remediation optimization based on validated therapeutic mechanisms.

Humans↗

PubMed1978

[Measurement of spinal cord blood flow in rabbits: central gray matter flow and CO2 reactivity (author's transl)].

Spinal cord blood flow (SCBF) was measured in 20 rabbits anesthetized with sodium pentobarbital. The platinum electrodes (0.3 mm in diameter) were inserted into the central gray matter of the thoracic spinal cord (Th8-10). In all animals, blood pressure and pAO2 remained constantly in the normal range. The pACO2 was changed by ventilation. Blood gases were checked both before and after each spinal cord blood flow measurement. The results are as follows. 1. Seventy-three percent of the clearances recorded from the gray matter were monoexponential and in the white matter almost all were monoexponential. 2. The mean values of gray matter SCBF of all animals was 38.3 +/- 1.85 ml/100 g/min (SE) at normo-capnea and the white matter was 19.5 +/- 1.33 ml/100 g/min. 3. An almost linear relationship exists between the pACO2 and SCBF. The values were 0.62 ml/100 g/min/torr in the gray matter and 0.38 ml/100 g/min/torr in the white matter.

Animals↗

PubMed1978

[Stimulation of the periaqueductal gray matter for pain : electrical activity and evoked potentials (author's transl)].

There is some evidence that stimulation of the periaqueductal gray matter produced analgesia is accomplished by the activation of neuronal systems where endorphins are thought to be transmittors. However, the neurophysiological mechanism of this stimulation is not elucided. In this preliminary paper, the spontaneous and the evoked electrical activity has been studied in 3 patients operated on with implantation of an electrode in the periaqueductal gray matter for chronic pain. Particularly interesting are the pronounced decrease of the evoked potentials in the sensory nucleus of the thalamus after stimulation of the periaqueductal gray matter.

Aged↗

PubMed1977

Pain reduction by electrical brain stimulation in man. Part 2: Chronic self-administration in the periventricular gray matter.

Electrical stimulation of the periventricular gray matter is an effective means of relieving several types of pain without destruction of neural tissue. The effects are long lasting, often bilateral, and with judicious use do not appear subject to adaptation. However, sustained uninterrupted stimulation for several hours does lead to a reversible decrease in effectiveness. Side effects from stimulation are minimal and cause little or no untoward emotional changes. The results are discussed in terms of activation of an endogenous pain inhibitory mechanism that involves naturally occurring opiate-like factors such as the enkephalins and endorphins.

Adult↗

PubMed1992

Organization of medullary adrenergic and noradrenergic projections to the periaqueductal gray matter in the rat.

The periaqueductal or midbrain central gray matter (CG) in the rat contains a dense network of adrenergic and noradrenergic fibers. We examined the origin of this innervation by using retrograde and anterograde axonal tracers combined with immunohistochemistry for the catecholamine biosynthetic enzymes tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyltransferase (PNMT). Following injections of the fluorescent tracers Fast Blue or Fluorogold into the CG, double-labeled neurons in the medulla were identified mainly in the noradrenergic A1 group in the caudal ventrolateral medulla (VLM) and A2 group in the medial part of the nucleus of the solitary tract (NTS); and in the adrenergic C1 group in the rostral ventrolateral medulla and C3 group in the rostral dorsomedial medulla. Injections of Phaseolus vulgaris-leucoagglutinin (PHA-L) into these cell groups resulted in a distinct pattern of axonal labeling in various subdivisions of the CG. Anterogradely labeled fibers originating in the medial NTS were predominantly found in the lateral portion of the dorsal raphe nucleus and in the adjacent part of the lateroventral CG (CGlv). Following PHA-L injections into the C3 region the anterogradely labeled fibers were diffusely distributed in the CGlv and the dorsal raphe nucleus at caudal levels, but rostrally tended to be located laterally in the CGlv. In contrast, ascending fibers from the caudal and rostral VLM terminated in the rostral dorsal part of the CGlv and in the dorsal nucleus of the CG, whereas ventral parts of the CG, including the dorsal raphe nucleus, contained few afferent fibers. Double-label studies with antisera against DBH and PNMT confirmed that noradrenergic neurons in the A1 and A2 groups and adrenergic neurons in the C1 and C3 groups contributed to these innervation patterns in the CGlv. Noradrenergic and adrenergic projections from the medulla to the CG may play an important role in a variety of autonomic, sensory and behavioral processes.

Adrenergic Fibers↗

PubMed1992

The extracellular matrix of cerebral gray matter: Golgi's pericellular net and Nissl's nervösen grau revisited.

Glial hyaluronate-binding protein (GHAP) and a large aggregating chondroitin sulfate proteoglycan (Ag-Pg) similar to a fibroblast proteoglycan (versican) were localized in bovine, dog and cat central nervous system (CNS) gray matter by indirect immunofluorescence. The distribution of the two hyaluronate-binding proteins was identical with that of hyaluronate, an extracellular glycosaminoglycan. All substances formed a finely reticulated mesh in the neuropil with a condensation of the stain around large neurons. It is concluded that in gray matter, as in white matter, the extracellular matrix (ECM) contains hyaluronate-protein aggregates. We suggest that the hyaluronate-protein aggregates correspond to the pericellular network first described by Golgi.

Animals↗

PubMed1976

Inhibition of visceral pain by electrical stimulation of the periaqueductal gray matter.

Numerous recent studies demonstrated that electrical stimulation of the periaqueductal gray matter (PGM) can result in powerful analgesia to pain of somatic origin. In the present study, we have developed a visceral pain test employing intraperitoneal injection of hypertonic saline which yields a writhing response in the adult rat more reliably than other pain-producing substances. With this test we show that writhing as well as the response to radiant heat (tail flick test) are completely inhibited in all animals with PGM electrode placements.

Analgesia↗

PubMed1978

Malformation of the cerebral cortex with heterotopia of the gray matter.

Developmental malformation of the cerebral cortex with heterotopia of the gray matter is a rare condition. It can present as unilateral megalencephaly, a localized mass, or focal cortical dysplasia. Four histologically confirmed cases are described in this report, and the findings from computed tomography as well as from other radiological diagnostic procedures are discussed.

Brain Neoplasms↗

PubMed1978

Opiate effects after adrenocorticotropin or beta-endorphin injection in the periaqueductal gray matter of rats.

Injections of adrenocorticotropic hormone (ACTH) into the periaqueductal gray matter of drug-naive rats resulted in a dose-dependent opiate abstinence syndrome characterized by fearful hyperreactivity and explosive motor behavior. Injecting shorter chains of ACTH caused attenuated forms of this behavior. Injections of beta-endorphin at this same site caused opposite behavior: sedative, analgestic, and catatonic. If the effects of morphine are mediated by two classes of receptor) and the other which is not stereospecific and naloxone-insensitive--the endogtor)--and the other which is not stereospecific and naloxone-insensitive the endogenous ligand of the second receptor may be ACTH. The neuropeptides ACTH and endorphin may be part of an integrated neuromodulatory system, and the opiate abstinence syndrome may be the result of an altered interaction between the two receptor systems.

Adrenocorticotropic Hormone↗

PubMed1977

Two copper-containing proteins from white and gray matter of brain.

The procedure for the isolation of two water soluble copper-containing proteins from the white and gray matter of bovine brain is described. One of the proteins, cerebrocuprein I, is superoxide dismutase; and three molecular forms of this enzyme are to be found in brain. The other protein present in gray and white matter is devoid of superoxide dismutase and amine oxidase activities. The amino acid composition, molecular weight, isoelectric point and copper content of this protein were determined. The effect of some agents, pH and thermal treatment of the optical and EPR spectra of the protein were also studied. The copper of the protein may be removed and the holoprotein reconstituted again from apoprotein and copper. The results obtained led to the conclusion that in brain a new copper protein is discovered, which is named neurocuprein.

Amino Acids↗

PubMed1992

Periaqueductal gray matter stimulation-produced analgesia in diabetic rats.

The effect of diabetes on periaqueductal gray matter (PAG) stimulation-produced analgesia (SPA) was examined in rats. PAG SPA was assessed using the tail-pinch test. PAG stimulation produced marked analgesia in both naive and diabetic rats. Furthermore, the degree of PAG SPA did not differ between naive and diabetic rats. PAG SPA was significantly attenuated by a low dose (0.5 mg/kg, s.c.) of naloxone in naive rats, but not in diabetic rats. However, a high dose (5 mg/kg, s.c.) of naloxone significantly and equally attenuated PAG SPA in both naive and diabetic rats. On the other hand, the analgesic potency of morphine (3 mg/kg, s.c.) was significantly reduced in diabetic rats as compared with naive rats. These results suggest that PAG SPA in diabetic rats may be mediated by different opioid receptor interactions as compared with naive rats.

Animals↗

PubMed1976

Intranuclear bodies in neurons of the periaqueductal gray matter in the cat.

The nucleoplasm of neurons in the nucleus lateralis of the periqueductal gray matter in the cat contains fibrillar structures which have no limiting membranes. These intranuclear bodies are associated with neither the nucleolus nor the nuclear membrane and have two characteristic forms. The first, the rodlet, is a compact bundle of fibrils 2 to 8 nm in diameter. It is usually elongated in shape although it appears spherical when sectioned transversely. This rod-like structure appears to correspond to Roncoroni's rodlet or the accessory body of Cajal in light microscopy. The second and more commonly observed form is a long slender bundle of five rows of parallel fibrils. Although similar intranuclear structures have frequently been observed in the highly differentiated neurons of the sympathetic ganglia and the retina, this is the first report of their pbesence in the undifferentiated neurons of the isodendritic core of the brainstem.

Animals↗

PubMed1976

Cholinergic and serotonergic neural links and the inhibitory effects of hippocampus, lateral amygdala and central gray matter on gonadotropin release.

Effects of electrical stimulation of the hippocampus (HPC), lateral amygdala (1-AMYG) and midbrain central gray matter (CG) on the release of ovulatory gonadotropin were examined using proestrous Wistar rats with or without pretreatment with reserpine, atropine or p-chlorophenylalanine (PCPA) at such dosage that had been confirmed not to block ovulation. Electrical stimulation of the HPC, 1-AMYG or CG under light ether anesthesia just before the critical period prevented a rise in serum LH, FSH and prolactin levels at 18:00. Pretreatment with atropine (200 mg/kg body wt, sc) was effective to abolish this inhibitory effect of the HPC stimulation on the release of LH and FSH, whereas reserpine treatment (1mg/kg body wt, ip) did not affect the effect. The inhibitory effect of the 1-AMYG or CG stimulation on LH and FSH release was abolished by treatment with PCPA (150 mg/kg body wt, ip), while neither atropine nor reserpine had any effect. The inhibitory effect of the HPC stimulation on the release of these hormones was also blocked by PCPA treatment. In regard to the prolactin release, it was inhibited by the stimulation of the HPC, 1-AMYG or CG in both the non-treated rat and in the atropine or PCPA-treated one, while in the reserpine-treated rat it was not inhibited but rather was facilitated by these stimulations. It was assumed that the normal maintenance of both cholinergic and serotonergic neural links for the expression of the HPC inhibition on ovulatory LH, FSH and prolactin secretion and that of serotonergic link for the expression of the 1-AMYG or CG inhibition are needed. The inhibitory action on prolactin release changed into facilitation under the depletion of monoamines, but the mechanism is unknown.

Amygdala↗

PubMed1978

A statistical method for determining the proportions of gray matter, white matter, and CSF using computed tomography.

The brain may be considered as a collection of volume elements (voxels) containing unknown proportions of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF). If one assumes that (1) the attenuation coefficients for voxels with the same proportions of GM, WM, and CSF follow a Gaussian distribution whose mean is a weighted average of the mean attenuation coefficients of pure GM, WM, and CSF and (2) the voxel-to-voxel variation in proportion follows a Dirichlet probability distribution, then the overall proportions of GM, WM, and CSF can be calculated by optimizing the parameters of a compound Dirichlet-Gaussian distribution. This approach permits a quantitative analysis of the compartmental composition of the brain and may be useful in the evaluation of patients with cerebral edema, hydrocephalus, and leukoencephalopathy.

Brain↗

PubMed1979

Inhibition of spinal cord interneurons by narcotic microinjection and focal electrical stimulation in the periaqueductal central gray matter.

Single cell evoked activity was recorded from spinal cord interneurons in rats prepared with microinjection cannulae or stimulating electrodes in the periaqueductal central gray matter (PAG). Morphine microinjections (4-16 microgram) inhibited the response evoked by a noxious stimulus in 55% of the wide dynamic range neurons tested. Microinjections of etorphine (0.25-0.5 microgram) inhibited 82% of the nociceptive neurons tested. Neither drug inhibited neurons which responded only to innocuous mechanical stimulation. The inhibition of wide dynamic range neurons produced by narcotic microinjection was antagonized by naloxone (1 mg/kg, i.p.) in 7 of 11 cases. Control experiments indicated that the effects obtained with microinjections could not be attributed to the drugs' diffusion to the spinal cord. Focal electrical stimulation of the PAG inhibited the responses to noxious stimuli of 60% of wide dynamic range neurons but was without effect on the responses of neurons that were activated only by innocuous stimuli. These experiments directly demonstrate that narcotic analgesics restricted to an intracerebral site of action activate a neural system which preferentially inhibits the responses of spinal cord wide dynamic range neurons to noxious stimuli. The system has a specificity for nociceptive input since non-nociceptive neurons were unaffected. Directly comparable results were produced by electrical stimulation of the PAG, supporting the concept that stimulation and narcotics modulate the transmission of nociceptive information by similar mechanisms.

Animals↗

PubMed1975

Oxygen tension in spinal cord gray matter during exposure to hyperbaric oxygen.

Adult female rats were exposed to 60 psig of 100% oxygen for 60 minutes. Oxygen tensions in the gray matter of the lumbosacral enlargement of the spinal cord, electroenecephalograms, electrocardiograms, and respirations were monitored before, during, and after the compression periods. Oxygen tensions were found to rise sharply to as high as 1050 mm Hg during compression and remained at significantly high levels throughout the entire hour of exposure. These data support the hypothesis that spinal cord lesions induced by exposure to hyperbaric oxygen are the result of excessive tissue oxygenation.

Animals↗