The results of this latest study were published in the journal NeuroReport. The scientists used DTI — which tracks the movement of water through brain tissue — to measure the structural integrity of the white matter that acts as cables to wire the parts of the brain together.
Normally, water molecules move, or diffuse, in a direction parallel to the orientation of the nerve fibers of the white matter. They're aided by the coherent structure of the fibers and a process called myelination, in which a sheath is formed around the fibers that speeds nerve impulses. The movement of water is more dispersed if the structural integrity of the tissue is low — i.e., if the fibers are less dense, less coherently organized, or less myelinated — as it was with the participants with autism in the Carnegie Mellon study. Researchers found this dispersed pattern particularly in areas in and around the corpus callosum, the large band of nerve fibers that connects the two hemispheres of the brain.
"These reductions in white matter integrity may underlie the behavioral pattern observed in autism of narrowly focused thought and weak coherence of different streams of thought," said Marcel Just, director of the Center for Cognitive Brain Imaging and a co-author of the latest study. "The new findings also provide supporting evidence for a new theory of autism that attributes the disorder to underconnectivity among brain regions," Just said.
In 2004, Just and his colleagues proposed the underconnectivity theory based on a groundbreaking study in which they discovered abnormalities in the white matter that suggested a lack of coordination among brain areas in people with autism. This theory helps explain a paradox of autism: Some people with autism have normal or even superior skills in some areas, while many other types of thinking are disordered.
Last summer, Just led a team of researchers that found for the first time that the abnormality in synchronization among brain areas is related to the abnormality in the white matter. They discovered that key portions of the corpus callosum seem to play a role in the limitation on synchronization. In people with autism, anatomical connectivity — based on the size of the white matter — was found to be positively correlated with functional connectivity, which is the synchronization of the active brain regions. They also found that the functional connectivity was lower in those participants in whom the autism was more severe.
These studies, along with the latest paper, are providing a comprehensive picture of the autistic brain, whose components operate with less coordination than is normally the case, and which is less reliant on frontal components and more reliant on posterior components. The latest DTI finding shows that some of the frontal-posterior communication fiber tracts are abnormal, consistent with the lower degree of frontal-posterior coordination.
"The brain components in autism function more like a jam session and less like a symphony," Just said.
The latest study was co-authored by Rajesh K. Kana and Timothy A. Keller of the Center for Cognitive Brain Imaging. This research was supported by the National Institute of Child Health and Human Development.
Jonathan Potts | EurekAlert!
'Icebreaker' protein opens genome for t cell development, Penn researchers find
21.02.2018 | University of Pennsylvania School of Medicine
Similarities found in cancer initiation in kidney, liver, stomach, pancreas
21.02.2018 | Washington University School of Medicine
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
21.02.2018 | Life Sciences
21.02.2018 | Life Sciences
21.02.2018 | Materials Sciences