This Autism Speaks fellow is studying brain connections to deepen understanding of autism’s challenges and strengths
By neuropsychologist Aarti Nair, currently a postdoctoral scholar and clinical instructor at the Semel Institute for Neuroscience and Human Behavior of the University of California, Los Angeles. Dr. Nair was part of the 2012 class of Autism Speaks Weatherstone Predoctoral Fellows. Her fellowship project involved research into brain connectivity and function in adolescents with autism.
As a college freshman, I had the privilege of volunteering at the Mumbai branch of Mother Theresa’s Missionaries of Charity. In serving the poor, the center had the special mission of caring for those affected by physical, mental and neurological challenges.
I was powerfully drawn to the children with neurodevelopmental disorders. I spent hours with them every Sunday. I was struck by their diversity of strengths and talents, despite their being non-verbal and severely affected by repetitive and sensory behaviors.
Some were artists. Others were musicians or mathematicians. Above all, each was unique in his or her special combination of interests and skills. The inter-relationships between their social and sensory deficits and their intellectual strengths was striking. The year I spent with these children became the driving force that launched my career in psychological research.
I knew I had found my passion the first day I spent working in an autism brain-imaging lab. Magnetic resonance imaging (MRI) gives us a noninvasive method for studying the brain and brain activity in those who participate in our research. This allows us to answer important questions and gain insights into the nature of autism and how it affects people.
When the time came to develop my dissertation project in graduate school, my mind went back to Mumbai and the time I spent with children and teens on the autism spectrum. I thought about how profoundly the tradeoff between their remarkable abilities and their repetitive and sensory behaviors shaped their lives.
Thanks to the support of my Autism Speaks fellowship, I pursued MRI imaging studies that looked at connectivity and function in deep brain structures. I did so under the guidance of my graduate mentor Ralph-Axel Müller and with the generous participation of the children and teens in my study.
Understanding the thalamus
The thalamus is a crucial deep-brain structure involved in processing incoming information such as vision, hearing and movement. The thalamus sends this sensory information to specific regions within the brain’s outer layer – the cerebral cortex. The cerebral cortex processes the information and sends feedback to the thalamus. This two-way communication between the cortex and the thalamus makes it possible for a person to respond to incoming information.
Prior brain imaging studies had identified highly specific connection patterns between the thalamus and the cerebral cortex in the neurotypical brain. However, scientists had done little imaging research on the connections between the thalamus and the cortex in people who have autism.
Our research findings suggested that, in children and teens affected by autism, the pathways connecting the cerebral cortex and thalamus develop in a way that interferes with communication between these two parts of the brain.
Specifically, we found a pattern of over-connectivity between the thalamus and some regions of the cerebral cortex and under-connectivity to others. The over-connectivity was with regions involved in spatial memory, auditory processing and other sensory functions. Previous research suggests that these connections arise during an early stage of brain development.
By contrast, we saw under-connectivity between the thalamus and later-maturing parts of the cortex. These areas involved social information processing, emotion regulation and impulse control.
The changes associated with early brain overgrowth may help explain a wide range of impairments that affect many people with autism. These include social communication difficulties, sensory challenges and issues with self-regulation. Along these lines, our findings are consistent with growing evidence that changes in brain connectivity, or “wiring,” play a big role in the sensory and motor challenges faced by many children and adults on the autism spectrum.
This study was the one of the first published works to combine both functional and structural MRI imaging techniques to examine connections between the cerebral cortex and the thalamus in people with autism. In addition to the support of my Autism Speaks fellowship, it received funding from the National Institutes of Health.
For more on this study, also see “Study Links Autism to Impaired Brain Relay Station.”
Today, I am continuing this line of research as a postdoctoral researcher at the UCLA Ahmanson-Lovelace Brain Mapping Center. Currently, I’m examining how early we can see the diverging pattern of thalamus-cortex connections in infants who are at high-risk for developing autism. Our primary aim is to determine whether there’s an association between the time at which these atypical deep brain connection emerge and the onset of autism symptoms.
Our goals include identifying early biomarkers of autism and then guiding the development of early interventions that support the healthy development of these brain connections.
I am grateful to Autism Speaks and the Weatherstone Predoctoral Fellowship for making my research possible and for providing young investigators a platform to launch our careers in autism research. From the bottom of my heart, I send a big thank you to all the families that take time out of their busy schedules to support our research.