Similarity and variation in gene expression among human cerebral cortical subregions revealed by DNA macroarrays: technical consideration of RNA expression profiling from postmortem samples

The functional regionality of the human cerebral cortex suggests that a set of genes might be activated in each subregion of the neocortex to support its specific functions. To test this hypothesis, we employed the DNA array technique to compare the mRNA expression profiles of three neocortical subr egions of the human brain: prefrontal cortex (Area 46), motor cortex (Area 4) and visual cortex (Area 17). The macroarray analysis on high quality mRN A from postmortem brains revealed that the expression profiles of the diffe rent cortical areas are almost similar: only six out of 1088 known genes ex hibited significant differences (>2-fold) in their expression. RT-PCR studi es with an increased number of samples confirmed that expression of only tw o genes, annexin II and early growth response protein 1, varied by 2-fold a mong the regions, whereas expression of the others showed large inter-indiv idual difference. These results suggest that the whole neocortex of humans is more homogeneous than we expected at the level of gross gene expression profiles. In parallel, sensitivity and accuracy of radioisotope-based DNA m acroarrays and fluorescence-based DNA microarrays were tested. (C) 2001 Els evier Science B.V. All rights reserved.