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Brain's Magnetic Fields Reveal Language Delays in Autisim

Publication:Bench to Bedside

In a study that has gained national attention, investigators from The Children’s Hospital of Philadelphia have found that faint magnetic signals from brain activity in children with autism show that those children process sound and language differently from non-autistic children.

Identifying and classifying these brain response patterns may allow for a more accurate autism diagnosis and possibly aid in devising more effective treatments for the developmental disorder.

Timing appears to be crucial. “Children with autism respond a fraction of a second more slowly than healthy children to vowel sounds and tones,” says study leader Timothy Roberts, Ph.D., vice chair of radiology research and holder of the Oberkircher Family Endowed Chair in Pediatric Radiology at Children’s Hospital. Dr. Roberts used a technology called magnetoencephalography (MEG), which detects magnetic fields in the brain, just as electroencephalography (EEG) detects electrical fields.

“The brain’s electrical signals generate tiny magnetic fields, which change with each sensation, and with communication among different locations in the brain,” he adds.

Dr. Roberts is working to develop “neural signatures” that can link recorded brain activity to particular behaviors in children with autistic spectrum disorders (ASDs), which are characterized by impaired development in communications and social functioning. His team believes that speech and other sounds come in too fast for children with ASDs, and their difficulties in processing sound may impair their language and communication skills.

Physicians already use MEG to map the locations of abnormal brain activity in epilepsy, but the technology Dr. Roberts used is one of the few MEG machines available in a dedicated pediatric facility. In the current study, the investigators evaluated 64 children aged six to 15 at Children’s Hospital. Thirty children had ASDs; the rest were age-matched, typically developing control subjects.

The MEG machine has a helmet that surrounds the child’s head. The researchers presented a series of recorded beeps, vowels, and sentences. As the child’s brain responded to each sound, noninvasive magnetic detectors in the machine analyzed the brain’s changing magnetic fields.

When sounds were presented, the MEG recorded a delay of 20 milliseconds (1/50 of a second) in the brain’s response for children with ASDs, when compared with healthy control subjects. The delay showed that auditory processing is abnormal in children with autism, and may lead to a cascade of delay and overload in further processing of sound and speech. Dr. Roberts believes further research may shed light on how this delay in processing sounds may be related to interconnections among parts of the brain.

Other testing, measuring a response to mismatched or changed sounds, found longer delays, up to 50 milliseconds (1/20 of a second).

Because autism disorders range across a spectrum of functional abilities, explains Dr. Roberts, neural signatures based on brain responses may allow clinicians to more accurately diagnose which subtype of ASD an individual patient has. Such diagnoses may be possible at an earlier age if future studies show that such signatures are detectable in infancy—at younger ages than in the children involved in the current study.

Earlier diagnosis of ASDs may allow clinicians to intervene earlier with possible treatments. In addition, Dr. Roberts says that patients may also benefit from treatments for another neurological condition like epilepsy or attention-deficit hyperactivity disorder if the patient’s neural signature overlaps with the condition.

The National Institutes of Health, the Nancy Lurie Marks Family Foundation, and the Jeffrey and Christina Lurie Family Foundation provided funding support for the study. Dr. Roberts’ Children’s Hospital co-authors with Roberts were J. Christopher Edgar, Ph.D.; Deborah M. Zarnow, M.D.; and Susan E. Levy, M.D.