Published in Neuron, the study shows that language areas located in the right and left sides of the brain are less synchronized in toddlers with autism than in toddlers displaying either language delay problems or typical development. Within the autism group, the strength of synchronization was associated with individual language and communication abilities: the weaker the synchronization, the more severe the communication difficulties.
“Neural synchronization refers to the coordinated timing of neural activity across distinct brain areas,” said Ilan Dinstein, a neurobiologist at the Weizmann Institute of Science in Rehovot, Israel, a member of the UCSD Autism Center of Excellence, and first author of the study.
He continued: “In a normal brain, neurons in separate areas belonging to a system with a particular function, such as vision or language, always stay in sync, even during sleep. Our study shows that in most brains of toddlers with autism this ‘sync’ is significantly weaker in brain areas that are responsible for language and communication abilities. Many things need to be set up right during brain development to enable normal sync between different brain areas. The wiring between the brain areas needs to be right and the neurons within each brain area need to send and receive their messages properly.”
The findings, if corroborated by further research, could have significant impact, Dinstein said.
“With this study, we have made significant scientific progress in understanding autism at the genetic, behavioral and neurobiological levels,” said Marlene Behrmann, professor of psychology at Carnegie Mellon who has made other groundbreaking autism discoveries using brain imaging. “This work is one piece of a complicated puzzle as we try to identify and characterize potential biological markers. We hope to connect this work with geneticists to develop concrete descriptors as well as determining if the markers will predict different autistic patterns as children grow up.”
Dinstein agreed and stated, “It would be a biological rather than a behavioral measure that could be used to diagnose autism at a very young age — around one year. The functional magnetic resonance image (fMRI) scan would not identify all of the individuals with autism, but it would be helpful in revealing the majority of individuals. The results also tell us that significant differences in the biology of language areas are apparent during very early stages of autism development. It will help focus further research into the brain differences that underlie autism.”
Though the exact cause of autism remains unknown, it is hypothesized that the neurological disorder — which is marked by impaired social and communications skills, usually manifesting itself in the first few years of life — arises from the development of abnormal neural networks with irregular connectivity and synchronization.
Autism is a developmental disorder that progresses with time. It is currently impossible to identify autism at birth and diagnoses, which are entirely based upon observed behavioral symptoms, are typically performed only after the age of 3. These facts help make the study of how autism develops particularly challenging. Affected toddlers are prone to incessant movement and random, uncontrolled behaviors, both of which can disrupt efforts to measure brain function and structure using different imaging techniques.
To sidestep these difficulties, the research team studied toddlers’ brains at night while they were sleeping. This novel approach meant toddlers with severe autism, who are often left out of studies due to their challenging behaviors, could be included, thus permitting scientists to successfully test the strength of brain synchronization in children with different levels of development and identify the brain areas that exhibited weak synchronization in those with autism.
“We hope that this work will be one of several enlightening steps lead to a fuller understanding the underlying biology of autism during early development,” Dinstein said. “Such an understanding is critical for developing the necessary diagnostic and therapeutic tools that are so needed for successful early intervention.”
However, the researchers stressed that although this study is an important discovery, the research is still in early stages. “Parents should not run out to their doctor to request an MRI,” Dinstein said.
The research team also included Karen Pierce and Eric Courchesne, Autism Center of Excellence and the Department of Neurosciences, both at UCSD; Lisa Eyler, Autism Center of Excellence and Department of Psychiatry, UCSD; Stephanie Solso, Autism Center of Excellence, UCSD; Rafael Malach, Department of Neurobiology, Weizmann Institute of Science.
Funding for this study came, in part, from grants from the National Institute of Mental Health, the National Institutes of Health, the Israel Science Foundation and the Pennsylvania Department of Health.
Pictured above is Marlene Behrmann, professor of psychology at Carnegie Mellon.