Regional Dendritic Variation in Neonatal Human Cortex: A Quantitative Golgi Analysis

Basilar dendritic systems of lamina V pyramidal neurons were quantified to compare cellular differences across four regions of the neonatal cortex. Tissue was removed from the left hemisphere of four neurologically normal infants, and represented regions of Benson’s (1994) hierarchically arranged cortical processing model (low-integrative regions: primary areas, Brodmann’s area (BA) BA 4 and BA 3-1-2; unimodal area, BA 18; high-integrative association region: supramodal area BA 10). Tissue samples were stained using a modified rapid Golgi technique. The dendritic systems of 10 cells per region, per brain (N = 160) were quantified using a Neurolucida computer system (version 3.16 Microbrightfield Inc., Baltimore, MD). A nested MANOVA design (SAS System for Windows, Cary, v. 8.0) revealed that dendritic complexity significantly varied across cortical regions, primary regions BA 4 and BA 3-1-2 and unimodal region BA 18 exhibiting higher degrees of dendritic complexity than the supramodal area BA 10. Infant dendritic patterns were compared to those in adults to investigate heterochronous developmental trends of cortical regions. Overall, regional dendritic patterns suggest that cortical development is hierarchically organized by functional regions, the cellular systems of primary and unimodal regions developing first, followed by the supramodal association areas.