Altered posterior cingulate cortical cyctoarchitecture, but normal density of neurons and interneurons in the posterior cingulate cortex and fusiform gyrus in autism.
Autism brains have scrambled PCC layers but normal neuron counts, pointing to wiring problems rather than cell loss.
01Research in Context
What this study did
Scientists looked at brain tissue from people with autism after death. They focused on the posterior cingulate cortex, or PCC. This area helps with social thinking and self-awareness.
They counted neurons and checked how the layers were organized. They also looked at the fusiform gyrus, which helps recognize faces.
What they found
The PCC layers were scrambled in autism brains. White matter neurons were in the wrong spots. But the total number of neurons and interneurons was normal.
The fusiform gyrus looked normal. This means the problem is not cell loss. It is more like faulty wiring during development.
How this fits with other research
Kovačič et al. (2020) used fMRI to show weaker signals between the temporal lobe and PCC in living people with autism. This matches the structural mess Matson et al. (2011) found.
Karavallil Achuthan et al. (2023) saw less brain activity in the PCC of autistic children during rest. Again, the disorganized layers may explain why this area works poorly.
Pan et al. (2021) pooled many studies and listed PCC anomalies as part of broader neurological differences in autism. The 2011 findings fit right into that bigger picture.
Why it matters
When you see social attention problems, remember the PCC may be wired wrong. You cannot fix the layers, but you can teach skills that use other brain paths. Focus on clear prompts and visual supports that bypass the faulty wiring.
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02At a glance
03Original abstract
Autism is a developmental disorder with prenatal origins, currently estimated to affect 1 in 91 children in the United States. Social-emotional deficits are a hallmark of autism and early neuropathology studies have indicated involvement of the limbic system. Imaging studies demonstrate abnormal activation of the posterior cingulate cortex (PCC), a component of the limbic system. Abnormal activation has also been noted in the fusiform gyrus (FFG), a region important for facial recognition and a key element in social interaction. A potential imbalance between excitatory and inhibitory interneurons in the cortex may contribute to altered information processing in autism. Furthermore, reduced numbers of GABA receptors have previously been reported in the autistic brain. Thionin-stained sections were used to qualitatively assess cytoarchitectonic patterning and quantitatively determine the density of neurons and immunohistochemistry was used to determine the densities of a subset of GABAergic interneurons utilizing parvalbumin-and calbindin-immunoreactivity. In autism, the PCC displayed altered cytoarchitecture with irregularly distributed neurons, poorly demarcated layers IV and V, and increased presence of white matter neurons. In contrast, no neuropathology was observed in the FFG. There was no significant difference in the density of thionin, parvalbumin, or calbindin interneurons in either region and there was a trend towards a reduced density of calbindin neurons in the PCC. This study highlights the presence of abnormal findings in the PCC, which appear to be developmental in nature and could affect the local processing of social-emotional behaviors as well as functioning of interrelated areas.
Autism research : official journal of the International Society for Autism Research, 2011 · doi:10.1002/aur.188