Neuron density is decreased in the prefrontal cortex in Williams syndrome.
Williams syndrome brains have a neuron shortfall in the prefrontal cortex, yet brief social-skills training still helps.
01Research in Context
What this study did
Scientists compared brain tissue from people with Williams syndrome to typical brains. They focused on the prefrontal cortex, the area behind your forehead that plans and controls social behavior.
They counted neurons in thin slices of brain. The study looked at a specific spot called BA 10, deep layers V and VI.
What they found
The WS group had far fewer neurons in the prefrontal cortex. Other brain areas showed no clear loss.
The missing cells sat in the exact layers that send long wires to other brain regions. Fewer wires may mean weaker social control.
How this fits with other research
Finke et al. (2017) extends this work. They gave adults with WS a short social-skills lesson. Despite the neuron loss seen by Horton, the adults still learned new conversation rules. Brain shortage does not equal hopeless outcome.
Lough et al. (2015) and Diz et al. (2011) line up on the behavior side. Parents report that children and youth with WS often stand too close and struggle with back-and-forth talk. The neuron gap found here gives a physical reason for those everyday social slips.
Ng et al. (2015) seems to clash at first. Their WS adults could judge trustworthy versus shady characters, hinting the prefrontal cortex still works. The key difference is task load: a quick choice in a quiet lab asks less of the brain than real-world social chaos.
Why it matters
You now have a concrete brain fact to share with families: the prefrontal cortex has fewer neurons, so social rules need extra practice. Use short, clear lessons like the H et al. package, repeat them often, and add visual cues. Parent reports predict real-life success better than self-report, so keep parents in the loop when you set social goals.
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02At a glance
03Original abstract
Williams Syndrome (WS) is a rare neurodevelopmental disorder associated with a hemideletion in chromosome 7, which manifests a distinct behavioral phenotype characterized by a hyperaffiliative social drive, in striking contrast to the social avoidance behaviors that are common in Autism Spectrum Disorder (ASD). MRI studies have observed structural and functional abnormalities in WS cortex, including the prefrontal cortex (PFC), a region implicated in social cognition. This study utilizes the Bellugi Williams Syndrome Brain Collection, a unique resource that comprises the largest WS postmortem brain collection in existence, and is the first to quantitatively examine WS PFC cytoarchitecture. We measured neuron density in layers II/III and V/VI of five cortical areas: PFC areas BA 10 and BA 11, primary motor BA 4, primary somatosensory BA 3, and visual area BA 18 in six matched pairs of WS and typically developing (TD) controls. Neuron density in PFC was lower in WS relative to TD, with layers V/VI demonstrating the largest decrease in density, reaching statistical significance in BA 10. In contrast, BA 3 and BA 18 demonstrated a higher density in WS compared to TD, although this difference was not statistically significant. Neuron density in BA 4 was similar in WS and TD. While other cortical areas were altered in WS, prefrontal areas appeared to be most affected. Neuron density is also altered in the PFC of individuals with ASD. Together these findings suggest that the PFC is targeted in neurodevelopmental disorders associated with sociobehavioral alterations. Autism Res 2017, 10: 99-112. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1677