By neuroscientist Sarah H. Baum, an Autism Speaks Meixner Postdoctoral Research Fellow pursuing her fellowship project on autism-related sensory-processing challenges at the Vanderbilt Brain Institute. Dr. Baum uses a combination of neuropsychology, psychophysics and neuroimaging to discover the brain mechanisms involved in processing sensory information (sights, sounds, etc.) and spoken language.
As long as I can remember, I’ve been interested in how our brains make sense of all of the sights, sounds and other information around us and how we use this information to interact with the people and situations in our daily lives.
Understanding sensory perception in autism became a natural fit for this interest when I began working in the Multisensory Research Lab of Mark Wallace at Vanderbilt University. Thanks to the support of my Autism Speaks Meixner fellowship, I’ve been pursuing this research in ways that I hope will directly benefit children and adults on the autism spectrum.
As many readers of this column know, autism involves difficulty with social communication combined with restricted interests and/or repetitive behaviors. Understandably, most autism research has focused on these core features.
A neglected area of research
However, even the first descriptions of autism, published in 1943, note differences in how people with autism process sensory information from the world around them.
Though relatively little research has focused on these sensory-processing differences, I believe this avenue of study will provide promising clues to understanding autism and helping individuals affected by the condition.
The multisensory challenge of social interactions
Think about almost any social interaction. We have to process so many sensory clues to understand each other. Examples include the tone of someone’s voice, body language and facial expressions. We have to interpret so much sensory input while also integrating it with the literal content of the words we hear.
Most of what we know about sensory-processing differences in autism comes from questionnaires filled out by affected individuals, parents and other caregivers. This information has allowed researchers and clinicians to understand a great deal about the behaviors we see in people with autism. It also gives us clues about the types of situations where autism-related, sensory-processing difficulties occur.
But questionnaires have their limitations. They can’t help us see where these processing differences occur in the brain. Neither do they show us how the brain processes the many different sensory cues that make up a social interaction.
Delving deeper into sensory processing in social interaction
My research will help us understand what is happening in the brain when children with autism (ages 8 to 17) have to deal with complex social and sensory situations.
When participants first visit our lab, we ask them to complete a number of computer-based tasks while we assess how they process both simple (flashes and beeps) and more complex (speech) sensory information.
Some of the participants repeat these tasks inside a magnetic resonance imaging (MRI) scanner. The MRI gives us a safe and non-invasive way to look at their brain structure and function during these tasks.
This combination of behavioral testing and brain imaging allows us to look for significant differences in how sensory information is processed in the brains of people who have autism.
Our research builds on insights from earlier work on sensory processing in autism. For example, we found studies suggesting that it’s too simplistic to say that people with autism are simply worse at processing sensory information than are people we consider “neurotypical.” In some ways, people with autism tend to perform better than other people do. For example, when asked to judge the pitch of a spoken sentence, people with autism perform as well or better, on average, than the rest of us. However, when asked to identify the content of that spoken sentence, people with autism tend to perform much worse.
Research and clinical experience also suggest that people with autism are less able to combine sensory information. This ability, called “multisensory integration,” enables our brains to make sense of the multitude of sensory stimuli we encounter every day. Imagine a conversation with a friend sitting across from you. You use both the sound of her voice and her lip movements to understand what she’s saying – in addition to her expression and tone of voice. Without this ability to integrate information, navigating through social interactions becomes more difficult.
We need to understand why people with autism have difficulty with sensory processing in some situations but not others. To do so, we need to uncover the mechanisms that affect how our brains process sensory information.
This is the focus of my work – at both the behavioral and the neural, or brain-processing, level. In particular, I want to deepen our understanding of the relationships between simple sensory processing and the processing of more complex, multisensory information such as speech and social cues.
From new understanding to new treatments and supports
My ultimate goal is to use the findings from my research to improve treatment strategies that will help people with autism improve how they process speech and social information.
Our hypothesis is that by improving the processing of simple sensory information, we can produce a cascade of benefits in more complex sensory processing tasks such as understanding speech.
For example, if we can track how sensory cues interact in the brain and follow the timing of this interaction, we may be able to develop ways to help people with autism better integrate these cues. This, in turn, may make a real difference in their social skills and ability to tolerate situations that involve a lot of competing sensory information.
Through this research, I’ve had the pleasure of getting to know so many wonderful children – and quite a few adults – who have autism, along with their amazing families. We are so thankful for the time they’ve given us as study participants.
I’m likewise grateful to Autism Speaks’ large community of donors, fundraisers and volunteers for supporting this work.
We’re excited to see where this work takes us in our understanding of autism and how best to support individuals with autism. We promise to report on what we’ve learned along the way.