Abstract

A positive relationship appears to exist between information convergence and dendritic complexity in diverse cortical regions. An inverse relationship is hypothesized to exist between an area's dendritic complexity and cell packing density, at least for homotypical isocortical regions (Schlaug et al., 1993, Anat Embryol 187, 515-522). The present study examined these variables in Brodmann's area (BA) 10 and BA18, which were removed from the lateral aspect of the left hemisphere in 26 subjects (13 males; 13 females; mean age: 57±22 years). Cell packing densities were quantified with an optical fractionator (Stereo Investigator, Microbrightfield, Inc.) and were compared to total dendritic length (TDL) values previously quantified for the same tissue (Jacobs et al., 1997, J Comp Neurol 386, 661-680). Cell packing density in the less integrative and dendritically complex BA18 was 24% greater than in BA10, which is involved in higher-levels of (sub)cortical integration. The products of cell packing density and TDL for the two regions were nearly identical, demonstrating similar relative connectivity across both areas. The density decrease from BA18 to BA10 thus appears to reflect associated cortical differences in information convergence and processing. (Tissue generously provided by Dr. D. Bowerman of the El Paso County coroner's office, Dr. R. Sherwin of Penrose Hospital in Colorado Springs, Colorado, and Drs. E. Orsini and W. Tyson of Denver's Children's Hospital.)

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