Summary: Researchers have developed a revolutionary approach using diffusion MRI to explore the brain structures of people with autism spectrum disorder (ASD). This technique measures how water molecules move in the brain, revealing structural differences in the neural pathways of autistic and non-autistic individuals.
By applying mathematical models, the team linked these structural variations to functional impacts, notably in the way neurons conduct electricity and process information. Their findings, which correlate microstructural differences with autism diagnostic scores, promise to improve our understanding of ASD and could lead to more precise treatments.
Highlights:
- The UVA study used diffusion MRI to identify differences in brain microstructures between autistic and non-autistic individuals, revealing slower electrical conductivity in autistic brains due to variations in axon diameter.
- These structural differences were directly related to Social Communication Questionnaire scores, thereby enhancing the potential for precise diagnostic and therapeutic approaches.
- The research is part of the NIH Autism Center of Excellence initiative to pioneer a precision medicine approach to understanding and treating autism.
Source: University of Virginia
Autism spectrum disorders have not yet been linked to a single cause, due to the wide range of symptoms and severity.
However, a study led by University of Virginia researchers suggests a promising new approach to finding answers, one that could lead to advances in the study of other neurological diseases and disorders.
Current approaches to autism research involve observing and understanding the disorder through the study of its behavioral consequences, using techniques such as functional magnetic resonance imaging that map the brain’s responses to inputs. and activity, but little work has been done to understand the cause of these responses.
However, researchers from the College and UVA’s Graduate School of Arts & Sciences were able to better understand the physiological differences between the brain structures of autistic and non-autistic individuals through the use of diffusion MRI, a technique which measures molecular diffusion in biological tissues. to observe how water moves through the brain and interacts with cell membranes.
The approach helped the UVA team develop mathematical models of brain microstructures that helped identify structural differences in the brains of people with autism and those without autism.
“It hasn’t been well understood what these differences might be,” said Benjamin Newman, a postdoctoral researcher in UVA’s psychology department and a recent graduate of the University School of Medicine’s neuroscience graduate program. UVA and lead author of an article published this month in PLOS: One.
“This new approach examines the neural differences contributing to the etiology of autism spectrum disorders.”
Building on the work of Alan Hodgkin and Andrew Huxley, winners of the 1963 Nobel Prize in Medicine for describing the electrochemical conductivity characteristics of neurons, Newman and his co-authors applied these concepts to understand how this conductivity differs in people with autism and those without autism. , using the latest neuroimaging data and computational methodologies.
The result is a first-of-its-kind approach to calculating the conductivity of neuronal axons and their ability to carry information through the brain. The study also provides evidence that these microstructural differences are directly related to participants’ scores on the Social Communication Questionnaire, a common clinical tool for diagnosing autism.
“What we find is that there is a difference in the diameter of microstructural components in the brains of people with autism, which may cause them to conduct electricity more slowly,” Newman said. “It’s the structure that limits how the brain functions.”
One of Newman’s co-authors, John Darrell Van Horn, a professor of psychology and data science at UVA, said we so often try to understand autism through a set of behavioral patterns that can be unusual or seem different.
“But understanding these behaviors can be a little subjective, depending on who is observing,” Van Horn said.
“We need greater fidelity in terms of the physiological measures we have in order to better understand where these behaviors are coming from. This is the first time that this type of measurement has been applied to a clinical population, and it sheds interesting light on the origins of ASD.
Van Horn said a lot of work has been done with functional magnetic resonance imaging, looking at changes in blood oxygen-related signals in people with autism, but this research, he said, “go a little further”.
“It is not a question of whether there is a particular difference in cognitive functional activation; it’s about how the brain actually conducts information around it through these dynamic networks,” Van Horn said.
“And I think we were able to show that there is something particularly different about individuals diagnosed with autism spectrum disorder compared to typically developing control subjects.”
Newman and Van Horn, along with co-authors Jason Druzgal and Kevin Pelphrey of the UVA School of Medicine, are affiliated with the National Institute of Health’s Autism Center of Excellence (ACE), an initiative that supports activities multidisciplinary and multi-institutional on a large scale. studies on ASD with the aim of determining the causes of this disorder and potential treatments.
According to Pelphrey, a neuroscientist and brain development expert and principal investigator of the study, the overarching goal of the ACE project is to pave the way for the development of a precision medicine approach for autism.
“This study forms the basis of a biological target to measure treatment response and allows us to identify avenues for the development of future treatments,” he said.
Van Horn added that the study could also have implications for the examination, diagnosis and treatment of other neurological disorders like Parkinson’s disease and Alzheimer’s disease.
“This is a new tool for measuring the properties of neurons which is of particular interest to us. We’re still exploring what we could detect through this,” Van Horn said.
About this autism research news
Author: Russ Bahorsky
Source: University of Virginia
Contact: Russ Bahorsky – University of Virginia
Picture: Image is credited to Neuroscience News
Original research: Free access.
“Conduction velocity, G ratio, and extracellular water as microstructural features of autism spectrum disorders” by Benjamin Newman et al. PLOS ONE
Abstract
Conduction velocity, G ratio, and extracellular water as microstructural features of autism spectrum disorder
The neuronal differences contributing to the etiology of autism spectrum disorders (ASD) are not yet well defined. Previous studies have suggested that myelin and axons are disrupted during the development of ASD.
By combining structural and diffusion MRI techniques, myelin and axons can be assessed using extracellular water, global g-ratio, and a new approach to calculating axonal conduction velocity called axonal conduction velocity. global conduction, which is linked to the ability of the axon to carry information.
In this study, several innovative cellular microstructural methods, measured by magnetic resonance imaging (MRI), are combined to characterize differences between ASD and typically developing adolescents in a large cohort.
We first examine the relationship between each metric, including microstructural measures of axonal and intracellular diffusion and the T1w/T2w ratio.
We then demonstrate the sensitivity of these measures by characterizing differences between participants with ASD and neurotypical participants, finding widespread increases in extracellular water in the cortex and decreases in overall g-ratio and overall conduction velocity. throughout the cortex, subcortex, and white matter skeleton.
We finally provide evidence that these microstructural differences are associated with higher scores on the Social Communication Questionnaire (SCQ), a commonly used diagnostic tool to assess ASD.
This study is the first to reveal that ASD involves in vivo Differences in myelin and axon development with implications for neuronal and behavioral function.
We also introduce a new formulation to calculate the overall conduction velocity, which is very sensitive to these changes. We conclude that ASD may be characterized by otherwise intact structural connectivity, but that functional connectivity may be attenuated by network properties affecting neuronal transmission speed.
This effect may explain the putative reliance on local connectivity, in contrast to the more distal connectivity observed in ASD.
News Source : neurosciencenews.com
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