The Complete Source of Information

Abstract

The objective of this study was to measure myelination of frontal lobe changes in infants and young children. Twenty-four cases of infants and children (age range 12–121 months) were evaluated by a quantitative assessment of T2- weighted MR image features. Reliable quantitative changes between white and gray matter correlated with developmental age in a group of children with no neurological findings. Myelination appears to be an increasing exponential function with the greatest rate of change occurring over the first 3 years of life. The quantitative changes observed were in accordance with revious
qualitative judgments of myelination development. Children with periventricular leukomalacia (PVL) showed delays in achieving levels of myelination when compared to normal children and adjusted for chronological age. The quantitative measure of myelination development may prove to be useful in assessing the stages of development and helpful in the quantitative descriptions of white matter disorders such as PVL.

Introduction
The relations between brain development and behavior in human infants and young children are of interest to developmental psychologists. For example, there are changes in brain development that relate to the acquisition of perceptual and cognitive processes. Also of interest are developmental issues: how are the changes in myelination in the developing brain related to changes in social, emotional, and cognitive domains? Many of the changes in behavior, including social and emotional behavior, have been quantified; therefore, it would be useful to have a quantified measure of brain development to compare to the measures of behavior. A method of assessing developmental brain change is to assess the changing levels of myelination. One approach to assessing myelination is to view the stained samples of brain tissue from specimens. Histologic studies of myelination of the forebrain have found no myelinated fibers before the seventh fetal month. In the telencephalic division of the forebrain, myelinated fibers first appear in the white matter of the cerebral hemispheres in the tenth fetal month. In the supralimbic zone of the forebrain, which comprises the white matter of the cortical layers, the myelination of the subcortical white matter is synchronized with the myelination of cortical projections from the dorsolateral and posterior nuclei of thalamus. Read the rest of this entry »

Related posts

• Cognitive impairment patterns in Parkinson’s disease with visual hallucinations (0)
• Structural Abnormalities in the Brains of Human Subjects Who Use Methamphetamine (0)
• Social Investment and Personality: A Meta-Analysis of the Relationship of Personality Traits to Investment in Work, Family, Religion, and Volunteerism - Part 2 (0)
• PERSONALITY AND SOCIAL PSYCHOLOGY BULLETIN ESSENTIALISM AND PERSONALITY (0)
• Moral development of Japanese kindergartners (0)

Structural Abnormalities in the Brains of Human Subjects Who Use Methamphetamine

We visualize, for the first time, the profile of structural deficits in the human brain associated with chronic methamphetamine (MA) abuse. Studies of human subjects who have used MA chronically have revealed deficits in dopaminergic and serotonergic systems and cerebral metabolic abnormalities. Using magnetic resonance imaging (MRI) and new computational brain-mapping techniques, we determined the pattern of structural brain alterations associated with chronic MA abuse in human subjects and related these deficits to cognitive impairment. We used high-resolution MRI and surface-based computational image analyses to map regional abnormalities in the cortex, hippocampus, white matter, and ventricles in 22 human subjects who usedMAand 21 age-matched, healthy controls. Cortical maps revealed severe gray-matter deficits in the cingulate, limbic, and paralimbic cortices ofMAabusers (averaging 11.3% below control;p-0.05). On average,MAabusers had 7.8% smaller hippocampal volumes than control subjects ( p-0.01; left, p-0.01; right, p-0.05) and significant white-matter hypertrophy (7.0%; p - 0.01). Hippocampal deficits were mapped and correlated with memory performance on a word-recall test ( p- 0.05). MRI-based maps suggest that chronic methamphetamine abuse causes a selective pattern of cerebral deterioration that contributes to impaired memory performance. MA may selectively damage the medial temporal lobe and, consistent with metabolic studies, the cingulate–limbic cortex, inducing neuroadaptation, neuropil reduction, or cell death. Prominent white-matter hypertrophy may result from altered myelination and adaptive glial changes, including gliosis secondary to neuronal damage. These brain substrates may help account for the symptoms of MA abuse, providing therapeutic targets for drug-induced brain injury.
Key words: methamphetamine; brain imaging; drug abuse; MRI; cortex; hippocampus; limbic system; memory introduction Methamphetamine (MA) abuse is a growing epidemic worldwide. Read the rest of this entry »

Related posts

• Genetic influences on brain structure (0)
• Dynamically Spreading Frontal and Cingulate Deficits Mapped in Adolescents With Schizophrenia (0)
• Dynamic mapping of human cortical development during childhood through early adulthood (0)
• Negative symptoms: A review of schizophrenia, melancholic depression and Parkinson’s disease (0)
• PERSONALITY AND SOCIAL PSYCHOLOGY BULLETIN ESSENTIALISM AND PERSONALITY (0)