Autism and the Thalamus – Sensory and Motor Function

A Deep Brain Disorder

http://newscenter.sdsu.edu/sdsu_newscenter/news.aspx?s=74321

An SDSU research team has discovered that autism in children affects not only social abilities, but also a broad range of sensory and motor skills.

By Natalia Van Stralen

A group of investigators from San Diego State University’s Brain Development Imaging Laboratory are shedding a new light on the effects of autism on the brain.

The team has identified that connectivity between the thalamus, a deep brain structure crucial for sensory and motor functions, and the cerebral cortex, the brain’s outer layer, is impaired in children with autism spectrum disorders (ASD).

Led by Aarti Nair, a student in the SDSU/UCSD Joint Doctoral Program in Clinical Psychology, the study is the first of its kind, combining functional and anatomical magnetic resonance imaging (fMRI) techniques and diffusion tensor imaging (DTI) to examine connections between the cerebral cortex and the thalamus.

Nair and Dr. Ralph-Axel Müller, an SDSU professor of psychology who was senior investigator of the study, examined more than 50 children, both with autism and without.

Brain communication

The thalamus is a crucial brain structure for many functions, such as vision, hearing, movement control and attention. In the children with autism, the pathways connecting the cerebral cortex and thalamus were found to be affected, indicating that these two parts of the brain do not communicate well with each other.

“This impaired connectivity suggests that autism is not simply a disorder of social and communicative abilities, but also affects a broad range of sensory and motor systems,” Müller said.

Disturbances in the development of both the structure and function of the thalamus may play a role in the emergence of social and communicative impairments, which are among the most prominent and distressing symptoms of autism.

While the findings reported in this study are novel, they are consistent with growing evidence on sensory and motor abnormalities in autism. They suggest that the diagnostic criteria for autism, which emphasize social and communicative impairment, may fail to consider the broad spectrum of problems children with autism experience.

The study was supported with funding from the National Institutes of Health and additional funding from Autism Speaks Dennis Weatherstone Predoctoral Fellowship. It was published in the June issue of the journal, BRAIN.

About the Brain Development Imaging Laboratory

The Brain Development Imaging Laboratory conducts research seeking to understand how the brain develops and what functional organizational changes occur throughout childhood and adolescence. The research focuses on what happens when development is impaired and how brain abnormalities can explain developmental disorders such as autism.

In the lab, researchers use state-of-the-art techniques, such as functional connectivity magnetic resonance imaging (fcMRI) and diffusion tensor imaging, in the study of brain network connectivity. These imaging techniques use large magnets to safely take images of the brain and can pinpoint regions of brain activity, as well as structural features of the brain.

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Further Readings of Interest

The autism brain imaging data exchange: towards a large-scale evaluation of the intrinsic brain architecture in autism.

http://www.ncbi.nlm.nih.gov/pubmed/23774715

Abstract

Autism spectrum disorders (ASDs) represent a formidable challenge for psychiatry and neuroscience because of their high prevalence, lifelong nature, complexity and substantial heterogeneity.

Facing these obstacles requires large-scale multidisciplinary efforts. Although the field of genetics has pioneered data sharing for these reasons, neuroimaging had not kept pace.

In response, we introduce the Autism Brain Imaging Data Exchange (ABIDE)-a grassroots consortium aggregating and openly sharing 1112 existing resting-state functional magnetic resonance imaging (R-fMRI) data sets with corresponding structural MRI and phenotypic information from 539 individuals with ASDs and 573 age-matched typical controls (TCs; 7-64 years) (http://fcon_1000.projects.nitrc.org/indi/abide/).

Here, we present this resource and demonstrate its suitability for advancing knowledge of ASD neurobiology based on analyses of 360 male subjects with ASDs and 403 male age-matched TCs.

We focused on whole-brain intrinsic functional connectivity and also survey a range of voxel-wise measures of intrinsic functional brain architecture.

Whole-brain analyses reconciled seemingly disparate themes of both hypo- and hyperconnectivity in the ASD literature; both were detected, although hypoconnectivity dominated, particularly for corticocortical and interhemispheric functional connectivity.

Exploratory analyses using an array of regional metrics of intrinsic brain function converged on common loci of dysfunction in ASDs (mid- and posterior insula and posterior cingulate cortex), and highlighted less commonly explored regions such as the thalamus.

The survey of the ABIDE R-fMRI data sets provides unprecedented demonstrations of both replication and novel discovery. By pooling multiple international data sets, ABIDE is expected to accelerate the pace of discovery setting the stage for the next generation of ASD studies.Molecular Psychiatry advance online publication, 18 June 2013; doi:10.1038/mp.2013.78.

This entry was posted in Autism, co-morbid, Neurology, Physiology. Bookmark the permalink.

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