A large-scale study on gene expression profiling 20 anatomically distinct sites in the human CNS using the Affymetrix microarray suggested that different sites in the CNS fall into recognizable clusters corresponding to the CNS’s functional and anatomical groups, such as the cerebral cortex, basal ganglia, limbic system, forebrain, midbrain, hindbrain and spinal cord (Roth, et al., 2006). It was shown that the global transcriptome profile reflects the anatomy/function of the CNS and cluster-specific genes were detected, which ranged in number from 8 (in the hypothalamus) to ~2,000 (in the cerebellum). Another important finding of this study is that within groups—with the exception of the cerebellum and the spinal cord—very few substructures of the CNS, such as the putamen and the corpus callosum, contain transcriptions of region-specific genes, and no genes show differential expression among the tested cortical sites of the brain tissue from the occipital, parietal, frontal, and temporal lobes of the cortex (Roth, et al., 2006).
