A new study speculates that connections between brain cells might be deficient within single regions, and not just between regions, as was previously believed in autistic individuals.
The study was conducted by a team of researchers led by Tony Wilson at Wake Forest University School of Medicine.
As part of the study, using magnetoencephalography (MEG) brain imaging technology to measure brain electrical activity, the researchers administered a test called the 40 hertz (cycles per second) auditory steady-state response test. The test measures electromagnetic wave cycles and indicates brain cell discharges at the 40 hertz frequency.
A group of 10 children and adolescents with autism, and 10 without autism, listened to a series of clicks occurring every 25 milliseconds (ms) for a duration of 500 ms. The MEG measured the brain's responses to these clicks.
The study found that in the right hemisphere of the brain, which controls attention and spatial processing, there was no significant difference in the groups, but there was a considerable discrepancy between the two groups in the left hemisphere, the area of the brain that controls language and logic.
In the auditory area of the left hemisphere, the group without autism delivered a brain response to the 40 hertz stimulation 200 ms after it began. However, the group with autism failed to respond entirely at the same 40 hertz frequency.
"Our results made sense. Both anecdotal and behavioural evidence suggest children with autism have significantly disturbed brain circuits on the local-level within an individual brain area. For example, they tend to restrict their visual gaze to a part of someone's face, like a nose or an eye, but not the person's whole face," Wilson said.
The study supported the idea that the network as a whole is broken, but shows the disconnection in long-range connectivity might actually start within individual brain regions, known as local connectivity.
The findings of the study were published in the August issue of Biological Psychiatry.