Kim Cecil, a chemist and professor of radiology at Cincinnati Children's Hospital Medical Center and an expert on the impact of lead on the
brain, has found that whereas the language - function region of the
brain's left hemisphere is perturbed by chronic lead exposure,
corresponding regions in its right hemisphere show increased
activation in the presence of blood lead levels above current levels of concern.
Furthermore, movement - independent ZENK expression in the forebrain of night - migratory birds performing magnetic orientation at night is confined to Cluster N [with the strongest
activation in distinct subregions (the shell surrounding the DNH nucleus)-RSB-, as shown by the detailed quantification of ZENK expression within Cluster N performed in this study], and this expression massively decreased in
corresponding brain areas of non-migratory songbirds and in all bird species during daytime [13].