Imbalance of laminar-specific excitatory and inhibitory circuits of the orbitofrontal cortex in autism.
Xuefeng Liu, Julied Bautista, Edward Liu and 1 others
PMID 33081829WHAT IT FOUND
A frontal brain region involved in social and emotional processing had fewer neurons and thinner, sparser excitatory axons in postmortem tissue from adults with autism, while three inhibitory neuron types did not differ in density.
This is anatomy, not a therapy finding.
Key findings
01Myelinated axon density was lower in autism across all layers, with the difference most pronounced in deep layers.
02Axons were thinner in autism, with more thin axons and fewer medium and thick axons.
03Overall neuron density was lower in autism, while parvalbumin, calbindin, and calretinin inhibitory neuron densities did not differ significantly.
STILL TO COME
How it was doneWhat they found
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What it does not show
The sample was small: 10 adults total, with only 4 autism cases, and electron microscopy used 4 autism and 4 control cases. Only postmortem right hemisphere tissue from adults aged 30 to 67 was used, so it does not describe living brain function, children, or left-hemisphere differences. Comorbid diagnoses could not be reliably assessed; a case with epilepsy had thicker axons, and excluding that case changed the size of the axon thickness difference. The study measured cells and axons, not behaviour, communication, sensory processing, or therapy outcomes. The authors describe the findings as preliminary and say more studies are needed to address changes in inhibition.
Declared interests
Funding came from the National Institute of Mental Health and the Boston University Undergraduate Research Opportunities Program. The supplied text does not list author conflicts of interest.
The easy way to misread this
Do not read these cell and axon differences as proof that autism causes orbitofrontal dysfunction or that any therapy should change. The study examined postmortem tissue from a small number of adults and did not test behaviour, communication, or treatment response.