![]() ![]() Gray matter is primarily composed of neuron somas (the round central cell bodies), and white matter is mostly made of axons (the long stems that connects neurons together) wrapped in myelin (a protective coating). In the spinal cord, this order is reversed: The white matter is on the outside, and the gray matter sits within. In the brain, gray matter refers to the darker, outer portion, while white matter describes the lighter, inner section underneath. Gray and white matter are two different regions of the central nervous system. What is the gray matter and white matter? It contains blood vessels and nerves, including neurons and glial cells. The remaining 40% is a combination of water, protein, carbohydrates and salts. Weighing about 3 pounds in the average adult, the brain is about 60% fat. Together, the brain and spinal cord that extends from it make up the central nervous system, or CNS. They also plan to continue the longitudinal study with the same participants to evaluate if and how neural responses continue to change in older children.The brain is a complex organ that controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger and every process that regulates our body. His team is now studying children younger than age 6, because differences in brain development might be more pronounced then, he says. “We’re actually looking for a very radical change in the way people do pediatric research,” Edgar says. “This shows that this pattern of unusually rapid maturation followed by lulls may be recapitulated at various stages of development and that it extends to measures of brain function as well as structure,” says Carissa Cascio, associate professor at Vanderbilt University in Nashville, Tennessee, who was not involved in the study.Įdgar says he hopes this study will inspire other researchers to use smaller age ranges to obtain a more granular understanding of brain development in autistic and non-autistic children. Mounting evidence suggests that, compared with non-autistic children, autistic children undergo an early period of faster development followed by a period of slower development. The findings appeared August in the Journal of Autism and Developmental Disorders.ĭifferences in cortical gray matter and in the maturation of cells in the primary auditory cortex may be responsible for the autistic participants’ earlier onset of M100 responses and faster phase-locking development, Edgar and his colleagues hypothesize. ![]() Autistic participants demonstrated more mature phase-locking patterns at the first visit, which then diminished at the later two visits.Īll participants originally expected to return two times with about 18 months in between scans, but because of the COVID-19 pandemic, some were reevaluated outside of that interval, and some dropped out: 48 out of 66 autistic children and 43 of 61 non-autistic children returned for the second scan, and only 31 children from each group returned for the third. The team also evaluated ‘phase locking,’ a measure of how similar a participant’s neural activity is from scan to scan within a certain frequency band. By contrast, the M50 response, which occurs throughout life, beginning in utero, showed no significant difference between the two groups at any visit. But this difference disappeared in the next two visits, presumably because the M100 response typically appears during early adolescence. “If the two populations being studied have different rates of brain maturation, then the pattern of findings changes across time.”Īt the time of the first magnetoencephalography (MEG) scan, when the children were 6 to 9 years old, those with autism were more likely to have an M100 response to a barely audible tone in the right hemisphere than non-autistic children were. ![]() Christopher Edgar, associate professor of radiology at the Children’s Hospital of Philadelphia in Pennsylvania.įor that reason, longitudinal studies such as this one - in which Edgar and his colleagues assessed children at up to three different ages - are essential, he adds. “It’s a demonstration that when we look for autism markers in the brain, they can be very age-specific,” says lead investigator J. The finding suggests that the auditory cortex in children with autism matures unusually quickly, a growth pattern seen previously in other brain regions. A well-studied brain response to sound, called the M100, appears earlier in life in autistic children than in their non-autistic peers, according to a new longitudinal study. ![]()
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