Underconnectivity in Autism
by Kenneth Lyen
Recent studies on high functioning autistic individuals using functional magnetic resonance imaging (fMRI) showed that the the area of the brain responsible for understanding individual words, Wernickes area, was more active in autistic than non-autistic subjects. However, the area of the brain where the components of language are integrated to produce meaning, Brocas area, was less active in the autistic person. Furthermore, the activity between these two areas was less synchronised in the autistic compared to the non-autistic individual.
This has led to the conclusion that one of the possible causes of autistic speech delay may be an impairment in the neural connections between these two parts of the brain. The researchers have called this the "Underconnectivity Theory".
They postulate that the "Underconnectivity Theory" can be extended to other areas of the brain. That is, autistic patients may have impaired nerve connections to several regions of their brain.
It is an old observation that people with impaired function in one area can compensate by over-developing other areas. For example blind people have enhanced hearing and touch. Autistic individuals often display hypersensitivity to their environment, and some have special abilities, like mathematic calculations (as seen in the film, Rainman). Autistic subjects who possess exceptional abilities are well documented and their prowess can be quite phenomenal. These indiividuals are known as Autistic Savants.
The discovery of underconnectivity is potentially extremely important in the future elucidation of the cause and treatment of autism. The efficacy of speech therapy and medical treatment can be monitored objectively, and this will undoubtedly accelerate the development of more targeted and effective therapies.