Brain Development

Brain Enlargement in Autism due to Brain Changes Occurring Before Age 2

Source: 
Science Daily
Date Published: 
May 3, 2011
Abstract: 

In 2005, researchers from the University of North Carolina at Chapel Hill found that 2-year-old children with autism have brains up to 10 percent larger than children of the same age without autism. A follow-up study by UNC researchers has found that the children who had enlarged brains at age 2 continued to have enlarged brains at ages 4 and 5, but the amount of the enlargement was to the same degree found at age 2. This increased brain growth did not continue beyond 2 years of age and the changes detected at age 2 were due to overgrowth prior to that time point. In addition, the study found that the cortical enlargement was associated with increased folding on the surface of the brain (or increased surface area) and not an increase in the thickness of outer layer of the brain (or gray matter).

Atypical Neural Networks for Social Orienting in Autism Spectrum Disorders

Source: 
Neuroimage, Greene et al.
Date Published: 
May 2011
Year Published: 
2011

Researchers at UCLA used fMRI to examine the neural mechanisms involved in social interactions in autism spectrum disorders in order to provide insight into the social attention impairments that characterize the disorder. Researchers examined children and adolescents with ASD with social and nonsocial cues. Data revealed that in typically developing individuals, there was greater responsiveness for social cues than nonsocial cues, compared to ASD. The researchers concluded that this difference indicated that the autistic brain does not assign the same privileged status to social cues as assigned in the typically developing brain.

Aberrant Striatal Functional Connectivity in Children with Autism

Source: 
Biol Psychiatry, Di Martino et al.
Date Published: 
May 2011
Year Published: 
2011

BACKGROUND:

Models of autism spectrum disorders (ASD) as neural disconnection syndromes have been predominantly supported by examinations of abnormalities in corticocortical networks in adults with autism. A broader body of research implicates subcortical structures, particularly the striatum, in the physiopathology of autism. Resting state functional magnetic resonance imaging has revealed detailed maps of striatal circuitry in healthy and psychiatric populations and vividly captured maturational changes in striatal circuitry during typical development.

METHODS:

Using resting state functional magnetic resonance imaging, we examined striatal functional connectivity (FC) in 20 children with ASD and 20 typically developing children between the ages of 7.6 and 13.5 years. Whole-brain voxelwise statistical maps quantified within-group striatal FC and between-group differences for three caudate and three putamen seeds for each hemisphere.

RESULTS:

Children with ASD mostly exhibited prominent patterns of ectopic striatal FC (i.e., functional connectivity present in ASD but not in typically developing children), with increased functional connectivity between nearly all striatal subregions and heteromodal associative and limbic cortex previously implicated in the physiopathology of ASD (e.g., insular and right superior temporal gyrus). Additionally, we found striatal functional hyperconnectivity with the pons, thus expanding the scope of functional alterations implicated in ASD. Secondary analyses revealed ASD-related hyperconnectivity between the pons and insula cortex.

CONCLUSIONS:

Examination of FC of striatal networks in children with ASD revealed abnormalities in circuits involving early developing areas, such as the brainstem and insula, with a pattern of increased FC in ectopic circuits that likely reflects developmental derangement rather than immaturity of functional circuits.

Autism Spectrum Disorder Linked to Genetic Synaptic Behaviors

Source: 
Medical News Today
Date Published: 
April 21, 2011
Abstract: 

It seems that the place where your brain transfers electricity between synapses and how your genes determine how these processes function, are tied to autism in one way or another. There can be genetically driven disturbances in this process that lead to varying levels of autism according to a new study of DNA from approximately 1,000 autistic children and their kin.

Atlas Gives Scientists New View of the Brain

Source: 
The Wall Street Journal
Date Published: 
April 13, 2011
Abstract: 

Scientists funded by Microsoft Corp. co-founder Paul Allen unveiled a $55 million computerized atlas of the human brain Tuesday, offering the first interactive research guide to the anatomy and genes that animate the mind.

A project of the Seattle-based Allen Institute for Brain Science, the online atlas offers researchers a powerful new tool to understand where and how genes are at work in the brain. That could help them find new clues to conditions rooted in the brain, such as Alzheimer's disease, autism and mental-health disorders like depression.

Common Genetic Cause of Autism and Epilepsy Discovered

Source: 
Science Daily
Date Published: 
April 8, 2011
Abstract: 

Led by the neurologist Dr. Patrick Cossette, the research team found a severe mutation of the synapsin gene (SYN1) in all members of a large French-Canadian family suffering from epilepsy, including individuals also suffering from autism.

Visual Detection and Identification More Active in Autistic Brain Than Thought

Source: 
Medical News Today
Date Published: 
April 5, 2011
Abstract: 

Parts of the brains of people with autism are more active in areas that deal with visual detection and identification and less in areas for decision making, planning and execution, and cognitive control, researchers from the University of Montreal revealed in the journal Human Brain Mapping. Dr. Laurent Mottron, at CETEDUM (University of Montreal's Centre for Excellence in Pervasive Development Disorders) believes their findings explain why most people with autism tend to be extremely good at visual tasks.

MIT Researchers Recreate Autism in Mice

Source: 
Medical News Today
Date Published: 
March 20, 2011
Abstract: 

By mutating a single gene, researchers at MIT and Duke have produced mice with two of the most common traits of autism - compulsive, repetitive behavior and avoidance of social interaction. In this study, the researchers focused on one of the most common of those genes, known as shank3. Shank3 is found in synapses - the junctions between brain cells that allow them to communicate with each other. Feng, who joined MIT and the McGovern Institute last year, began studying shank3 a few years ago because he thought that synaptic proteins might contribute to autism and similar brain disorders, such as obsessive compulsive disorder.

Gene Variants in Autism Linked to Brain Development

Source: 
Science Daily
Date Published: 
March 7, 2011
Abstract: 

New research on the genomics of autism confirms that the genetic roots of the disorder are highly complicated, but that common biological themes underlie this complexity. In the current study, researchers have implicated several new candidate genes and genomic variants as contributors to autism, and conclude that many more remain to be discovered. While the gene alterations are individually very rare, they mostly appear to disrupt genes that play important functional roles in brain development and nerve signaling.

Gene Variants in Autism Linked to Brain Development

Source: 
Journal of Molecular Psychiatry, Gai et al.
Date Published: 
March 2011
Year Published: 
2011

This research on the genomics of autism confirms that the genetic roots of the disorder are highly complicated, but that common biological themes underlie this complexity. In the current study, researchers have implicated several new candidate genes and genomic variants as contributors to autism, and conclude that many more remain to be discovered. While the gene alterations are individually very rare, they mostly appear to disrupt genes that play important functional roles in brain development and nerve signaling. While an association between genomic variants in certain nervous system processes and autism has been hypothesized in the past, this research definitively links these biological functions to autism. 

"This large study is the first to demonstrate a statistically significant connection between genomic variants in autism and both synaptic function and neurotransmission," said senior author Peter S. White, Ph.D., a molecular geneticist and director of the Center for Biomedical Informatics at The Children's Hospital of Philadelphia. Synapses are the contact points at which nerve cells communicate with other nerve cells, while neurotransmitters are the chemical messengers carrying those signals.

"Prior genomic studies of autism have successfully identified several genes that appear to confer risk for autism, but each gene appears to contribute to only a small percentage of cases," said the lead author, Xiaowu Gai, Ph.D. "Our approach considered whether groups of genes with common biological functions collectively accounted for a greater percentage of autism risk."

-- via Science Daily http://www.sciencedaily.com/releases/2011/03/110301111243.htm.