Imaging Technology Explores Noisy Brains in Autism

A Children's Hospital of Philadelphia investigator is utilizing sophisticated imaging technology to determine how children with autism spectrum disorders (ASD) process sounds, words, and images. His findings are honing in on the biological basis for ASD and leading to the creation of novel interventions.

Timothy Roberts, PhD, vice chair of the department of radiology, uses magnetoencephalography (MEG) and advanced magnetic resonance imaging (MRI) to look at the "signatures" of brain functioning. Split-second differences in the timing, or frequency, of these signals can lead to auditory processing delays seen in some children with ASD.

Using this multi-modal approach, Dr. Roberts and colleague James (Chris) Edgar, PhD, identified a biomarker in the brain's white matter that may be the cause of auditory processing delays. And they have found a second one in a neurotransmitter called GABA. An inhibitory neuron, GABA must be in balance with another neurotransmitter - the excitatory glutamate.

"Those with ASD who have lower levels of GABA end up with a more 'noisy brain,'" Dr. Roberts said. "This is a problem because it means these children are trying to encode their perceptual reality, their world - and they are trying to encode it with rhythms in a sea of noise."

The tremendous variability, or heterogeneity, seen in children with ASD suggests that the problem for some may arise from abnormal white matter development and for others may stem from reduced GABA levels.

Knowing the biological differences at play has led Dr. Roberts to investigate a novel intervention for those whose ASD may arise from auditory processing difficulties. Dr. Roberts is collaborating with David Embick, PhD , from the department of linguistics at the University of Pennsylvania, to develop a device along the lines of a hearing aid that would remove the subtle variations in how we speak. It filters the incoming language to produce one voice that could help children with ASD better form the representations that build their language and vocabulary.