An exciting new study has just come out from Eric Courchesne's laboratory in San Diego which found that autistic children had about 67 per cent more meurons (nerve cells) in a part of
the brain known as the prefrontal cortex than children without autism. The research was reported in the Journal of the American Medical Association (JAMA). The prefrontal cortex is involved in processing social skills, communication, cognitive functions and language - all areas in which autistic children often show abnormal development.
Courchesne studied the brains of seven autistic boys between the ages of 2 and 16 after their death and compared his analysis to the brains of six unaffected boys who died at similar ages. The excess of neurons was a bit of a surprise, to say the least, since in most cases, deficits in social skills - like those typically observed in autistic children - are linked to less, not more, nerve tissue.
“When we think of the inability to handle complicated information, we usually think of too little in the way of connections or brain cells,” said Courchesne. “But this is just the opposite.”
This is a very significant study. A top neuroscientist, Dr Christine Ecker - currently taking part in Autism2011 (the Awares international online autism conference I am running at the moment at www.awares.org/conferences) - told me: I think Eric Courchesne's latest paper is groundbreaking. So far, we have known from many studies using Magnetic Resonance Imaging (MRI) that the frontal lobe is enlarged in individuals with autism, and also shows a more accelerated growth during in the age of 2-4. However, nobody knew what is causing this increase in frontal lobe volume. For instance, an increase in volume could be caused by a larger number of neurons but also by other factors such as neuronal connections (e.g. an increase in spine density). Unfortunately, the spatial resolution of techniques such as MRI is quite low so we can't visualize individual neurons and only look at the brain in millimeter resolution.
This is one of the first studies to demonstrate - in the postmortem brain - that the increase in frontal lobe volume is actually due to an increase in the number of neurons. Having this insight narrows down the potential genetic and molecular mechanisms of autism and might, in the future, provide new targets for intervention.
The next steps will now be to discover how these prefrontal neurons are connected within the frontal lobe, and also with other regions of the brain, and what effect this will have on autistic symptoms and traits.
Please feel free to comment on this study, if you have any observations.