Both hemispheric bias and sex differences exist in striatal-mediated behaviors and pathologies. The extent to which these dimorphisms can be attributed to an underlying neuroanatomical difference is unclear. We therefore quantified neuron soma size and density in the dorsal striatum (CPu) as well as the core (AcbC) and shell (AcbS) subregions of the nucleus accumbens to determine whether these anatomical measurements differ by region, hemisphere, or sex in adult Sprague-Dawley rats. Neuron soma size was larger in the CPu than the AcbC or AcbS. Neuron density was greatest in the AcbS, intermediate in the AcbC, and least dense in the CPu. CPu neuron density was greater in the left in comparison to the right hemisphere. No attribute was sexually dimorphic. These results provide the first evidence that hemispheric bias in the striatum and striatal-mediated behaviors can be attributed to a lateralization in neuronal density within the CPu. In contrast, sexual dimorphisms appear mediated by factors other than gross anatomical differences.
Bibliographical noteFunding Information:
We thank Valerie Hedges, Nancy Staffend, and Caroline Loftus for technical assistance, Katherine Ingram for help processing tissue, and Dr. Christopher K. Thompson for comments on a previous version of this manuscript. Grant Support: National Institutes of Health Grants NS41302 (P.G.M.), DA07234 (training grant supporting: J.M., C.M.S.), DA013680 (R.L.M.).
- Nucleus accumbens
- Sexual dimorphism