Many children diagnosed with an autism spectrum disorder have difficulty communicating and establishing social bonds with others. Many brain studies attempting to explain why this is so have focused on the visual system and the processing of visual signals, as manifested in, for example, the interpretation of facial expressions and the ability to maintain eye contact.
This time, a research team focusing on the processing of sound and speech signals reported its results. They sought to discover the neural underpinnings of another cause of social communication difficulties. It is a fact that many children with autism have difficulty recognizing emotional inflections in their voices. This is what we call emotional prosody. Examples are whether the voice expresses happiness, sadness, or emotionally neutral content. Being able to do this accurately is an integral part of interacting and bonding with others.
The team’s data, drawn from a controlled study of 43 children aged 7 to 12 years, 22 of whom were diagnosed with autism, found that the part of the cerebral cortex that processes sound is responsible for the emotions expressed. was not the cause of the problem in identifying the . Rather, their evidence suggests that the parts of the brain involved in interpreting these sounds, in particular the function and connectivity of a social processing hub called the bilateral temporoparietal junction (TPJ), appear to be involved. suggesting. It could potentially be a target for future treatments to improve social communication in people with autism.
Dr. Daniel A. Abrams, a 2018 BBRF Young Investigator, was co-first author of the team’s paper published in 2018. Biological Psychiatry: Cognitive Neuroscience and NeuroimagingA 1998 BBRF Junior Investigator, Dr. Vinod Menon, was a senior member of the team. He was also co-first author with Dr. Simon Leipold.
“Children typically learn to map specific sounds in a person’s voice to specific emotions,” explained Dr. Abrams. “If a mom or dad is unhappy, young children will know it before they understand every word. But children with autism often have trouble mapping vocal characteristics to emotions.” Yes, prior to this study, we didn’t understand why the brains of people with autism have impairments in identifying and recognizing these vocal cues.”
In this study, 22 children diagnosed with autism and 21 sociodemographically matched but ‘neurotype’ controls underwent two types of testing. In one, children were given a standardized test to recognize vocal emotion. The results of this emotion recognition test showed that children with autism were less able to correctly identify emotions from voice recordings than neurotypical children.
A second test was performed while the children were undergoing functional MRI brain scans. During the fMRI task, the children listened to two recorded sentences of her spoken in happy, sad, and neutral emotional tones, as well as recordings of common nonverbal sounds, such as the sound of a dishwasher running. I was. The goal was to compare the activity and connectivity of brain regions involved in processing speech signals for happy and sad emotions compared to neutral voices.
The study revealed that areas of the cortex involved in basic sound processing (the auditory cortex) exhibited similar functions in both groups of children. “What was atypical for autistic children was the way this signal reached a key social brain area known as the temporoparietal junction (TPJ),” says Dr. Abrams. In children with autism, during emotional speech processing, the TPJ showed an atypical connection pattern with parts of the auditory cortex that process speech signals. Moreover, the child with the greatest communicative and social impairment had the lowest level of activity in her TPJ during emotional speech processing, and indeed this level could predict the severity of deficits in a particular child. I was. Low TPJ activity was associated with speech with particularly sad inflections.
This evidence supports one of two leading theories as to why people with autism have difficulty discerning verbal emotions. The results do not support a ‘sensory deficit model’ that proposes that the problem is rooted in the auditory cortex and involves defective auditory processing of speech emotional signals. Rather, new data support a “social cognitive model.” This model hypothesizes that difficulties in vocal emotional processing are rooted in deficits in social brain regions such as her TPJ, which are associated with interpreting the emotional content of speech signals. Importantly, the TPJ and other parts of the “social brain” are believed to underlie what scientists call “theory of mind.” That is, the ability of an individual to understand the mental states and emotions of others.
If the results of this study can be replicated, it may help future treatments. For example, it may be possible to develop therapeutics that selectively enhance TPJ activity. Dr. Menon says this approach is a “very real possibility.”
Dr. Abrams also notes that the findings could support efforts to teach every child a lesson about neurodiversity. This is the concept that people with different types of brain wiring experience the world differently. “Everyone has to learn something if they are to really improve their communication with people with autism. It may be a struggle, but I want to get to know you and connect with you.” That extra knowledge may help keep people with autism in conversation. ”
