Extraordinary neoteny of synaptic spines in the human prefrontal cortex.
Level 4 - case-series / case-control
Cross-sectional postmortem anatomical study across human age cohorts (by design analogy, non-clinical)
PubMed 21788513 · doi:10.1073/pnas.1105108108
What was done
Researchers analyzed synaptic spine density on the dendrites of layer IIIC cortico-cortical and layer V cortico-subcortical projecting pyramidal neurons in postmortem prefrontal cortex tissue from human subjects aged newborn to 91 years.
What was found
Dendritic spine density in childhood was two- to threefold higher than adult levels and began to decrease during puberty. Synaptic spine overproduction and elimination continued past adolescence and throughout the third decade of life before reaching a stable adult baseline. Numerical spine densities, exact sample counts, and statistical intervals were not provided in the abstract.
Why it matters
The findings demonstrate extended developmental neoteny in human prefrontal cortex circuitry, showing that synaptic reorganization persists well into the third decade of life rather than finishing in early adolescence.
Limits
The investigation is a cross-sectional postmortem study unable to track longitudinal dynamics within individuals. The abstract does not specify the total sample size, postmortem interval, cause of death, or quantitative variance estimates.
Cited by
- supports The human brain develops hyperconnectivity of neuronal synapses over the first two years of life, after which brain development is characterized by synaptic pruning.