Picking up on innuendo and social cues is a central part of engaging in conversation, but people with autism often struggle to do so. The study sheds light on the neural mechanisms that are responsible for such social difficulties in autism.
The research implicates abnormalities in the brain's inter-regional communication system. "The communication between the frontal and posterior areas of the social brain network is impaired in autism, making it difficult to understand the intentions of others" said the study's senior author Marcel Just.
To measure the effectiveness of the Theory of Mind (ToM) network, that is responsible for processing the intentions and thoughts of others, the researchers asked twelve high-functioning autistic adults and twelve control participants to view animations of interacting geometric figures.
Participants were asked to choose the word that best described the interaction. For example, a large triangle would nudge a small triangle to move outside its enclosure, and the correct word choice would be "persuading". The control subjects were consistently better at inferring the intention from the action than the other group.
While the study participants were performing the task, the researchers used functional magnetic resonance imaging (fMRI) to measure activation levels in all of the cortical areas that compose the ToM network. They simultaneously examined activation levels in several frontal and posterior brain regions. The synchronisation level in the network was reliably lower in the group with autism.
Furthermore, the autistic participants' brains showed much lower activation levels in the frontal regions. These measures of brain activity in autism were correlated with how well each autism participant performed in the Happe's Strange Story Test - a pencil-and-paper assessment on the understanding of non-literal statements, such as figures of speech.
MEDICA.de; Source: Carnegie Mellon University