Speech and language acquisition are essentials for any individual to communicate and interact with those around them. Many autistic individuals experience difficulties with communication and speech. In fact, around 30% of persons with ASD may be minimally verbal (Tager-Flusberg, & Kasari, 2013). Some might wonder how the brain develops as language is acquired and ponder the neurological differences between verbal and minimally verbal individuals. This article aims to answer these queries and to outline the relationship between neurological development and language acquisition.
First, let’s discuss the link between brain development and language acquisition. Research has determined that infants are born with two basic connections between the language regions in the brain. It was also discovered that school-aged children, with the ability to speak, obtained a third neural connection (Brauer et al., 2013). This suggests that although babies already have the groundwork for language acquisition, more advanced language becomes achievable as the brain develops throughout childhood!
Neural connections in the brain can change throughout our entire lives. Changes in our neural networks come not only, from ageing, but also everything we experience! During infancy and childhood, nerves are more able to grow and become stronger (Brauer et al., 2013). In our teenage years, the growth begins to slow, making it more difficult to absorb new information. This suggests it is incredibly important to intervene early. Exposing the brain to language at a young age can strengthen the growth of the neural networks in the brain and bolster a child’s ability to use advanced language!
It’s important to note that this research is focused on neurotypical individuals. There is a ton of research that suggests that people with ASD have neurological differences that may hamper their development. One might ask, is there a biological reason behind difficulties with speech and language?
The short answer is... YES!
A new study found that altered brain wave patterns could be the culprit (Ortiz-Mantilla et al., 2019). When presented with an image and word matching task, it was found that both verbal and minimally verbal children showed a burst of brain activity which indicates the brains first try at understanding the image. Within half a second, the differences between the groups appeared. Only the children who were in the verbal group experienced a longer brain wave, known as the ‘positive slow wave.’ This wave indicates the brain's ability to call up words associated with the image (e.g., an image of a bird may be associated with words such as, wings, fly, feather etc.). However, children in the minimally verbal group did not experience this brain wave.
Children typically pick up language by a mechanism known as word-to-world mapping (i.e., by associating objects with their labels and other related words) (Ortiz-Mantilla et al., 2019). These findings suggest that this mechanism is disrupted in minimally verbal children with autism.
What’s more? Another study shows that children with ASD and poor language skills have different patterns of brain activity in the language centres of the brain! Compared to neurotypical children, fMRI scans show that children with ASD had significantly less brain activity in the superior temporal cortex, a key area for language and sound processing. This suggests that dampened activity in this region of the brain may contribute to difficulties with speech and language (Lombardo et al., 2015).
In sum, there is evidence to suggest that differences in brain waves and activity can cause difficulties with language acquisition. However, it also should be noted that the brain can change and grow new networks over time. So, if you are caring for someone with speech and language difficulties, stay hopeful and persevere!
Written by: Aileen
Brauer, J., Anwander, A., Perani, D., and Friederici, A. D. 2013. Dorsal and ventral pathways in language development. Brain Lang. 127:289–95. doi: 10.1016/j.bandl.2013.03.001
Lombardo, M. V., Pierce, K., Eyler, L. T., Carter Barnes, C., Ahrens-Barbeau, C., Solso, S., Campbell, K., & Courchesne, E. (2015). Different Functional Neural Substrates for Good and Poor Language Outcome in Autism. Neuron, 86(2), 567–577.
Ortiz-Mantilla, S., Cantiani, C., Shafer, V. L., & Benasich, A. A. (2019). Minimally-verbal children with autism show deficits in theta and gamma oscillations during processing of semantically-related visual information. Scientific reports, 9(1), 5072.
Tager-Flusberg, H., & Kasari, C. (2013). Minimally verbal school-aged children with autism spectrum disorder: the neglected end of the spectrum. Autism research : official journal of the International Society for Autism Research, 6(6), 468–478. https://doi.org/10.1002/aur.1329