In recent years researchers have gained an increased understanding of the relationship between motor skills and the development of language, particularly in autism spectrum disorder (ASD). Given the core deficit in verbal communication in children and adults on the spectrum, the improved understanding could, in time, aid them in better expressing themselves.
Here’s how: Communication—whether spoken, written or signed—entails the planning and execution of gestures, which of course rely on motor skills. Not surprisingly, if speech gestures are difficult for a person, so too will be language. Ongoing research lead by Maria Mody at the Martinos Center and Harvard Medical School appears to support this conclusion.
“However, what is becoming increasingly evident,” Mody says, “is that, despite their difficulties with speech, some individuals on the autism spectrum are capable of expressing themselves independently using either an iPad or an AAC (‘augmentative-alternative communication’) device. Perhaps manually selecting words and pictures on the device is easier than producing speech as the former requires simple and cognitively less demanding motor gestures—namely, pointing or pressing a button; speech, in contrast, requires rapid and carefully orchestrated movements of the tongue, lips, jaw, velum, larynx and pharynx.
Building on past neuroimaging findings from her group, which revealed a preference for visual over verbal processing strategies in ASD, her current work suggests investigating written communication as an alternative to spoken language in this population.
Mody, principal investigator of the Developmental Language and Reading Research Laboratory at the Center has spent the past couple of years exploring the relationship between the motor system and language.
The first step was to look for relationships between motor skills and speech-language deficits in autism spectrum disorder. In a study reported earlier this year in Journal of Autism and Developmental Disorders, she and colleagues from the MGH Lurie Center for Autism examined data from nearly 1800 children with autism who were enrolled in the Autism Speaks—Autism Treatment Network (AS-ATN) registry, which collects information from children from across 17 academic health centers in the US and Canada. In doing so, they identified interesting patterns of association between motor skills and language and social behaviors—between fine motor skills and both receptive and expressive language, for example.
These findings motivated an MEG study of activation in the brain during a simple motor task (pushing a button) in minimally verbal adults with autism spectrum disorder. Here, the researchers found significant differences in the supplementary motor area of the motor cortex between the subjects with autism and age‐matched controls—an exciting result, Mody says, as it provides neurophysiological evidence of an underlying deficit in motor control in this population.
The investigators have now proposed to follow up the MEG study with connectivity analysis, probing links between motor and speech areas in the brain under various linguistic demands, to better understand the contribution of the motor system to verbal deficits in minimally verbal adults with autism.
Mody believes that nurturing the development of literacy skills and written communication in people with autism may, in time, stimulate improvements in their speech capabilities.
“After all,” she says, “speech and print are flip sides of the same coin; reading co-opted spoken language areas in the brain. If we understand the cognitive capacities and sensorimotor capacities of individuals with ASD, we can build an intervention that allows them to use the pathways that are more comfortable for them.”
The exacerbating role of social communication deficits
Motor deficits aren’t the only impairments contributing to the difficulties with verbal interactions. Oftentimes people with autism also have social communication deficits, which can make verbal exchanges especially challenging.
In fact, these social deficits can be the result of motor impairment. In the earliest months of life, motor skills facilitate vocal imitation and the mimicking of facial expressions as infants engage their parents or caregivers. In doing so they open the door to social reciprocity and interpersonal interaction—cornerstones of what we think of as social skills. Motor deficits can lead to disruption of those early activities, with cascading effects with respect to the development of social communication abilities.
And this isn’t the only obstacle individuals on the spectrum can face. In a study published this year, the Martinos Center’s Nouchine Hadjikhani and colleagues looked at the tendency to avoid eye contact in people with autism and found that this is not simply due to a lack of engagement, as many had previously thought. Instead, the researchers showed, eye contact can cause overactivation in a particular part of the brain, so their avoiding eye contact is a way to mitigate this uncomfortable over-arousal.
All of which underscores the possible benefits of AAC and print communication for people with autism, Mody says.
“Because individuals on the spectrum have social communications deficits, verbal interactions can be particularly challenging. As such, print provides a means to express themselves, while circumventing the social communication problems. Literary-focused intervention has the potential to open up new opportunities for expression and self-reliance as they seek to navigate society given their social and verbal limitations.”