The biological basis for electroencephalogram (EEG)/average evoked potential (AEP) correlations to intelligence measures is not yet clear. Neural transmission speed (often measured as nerve conduction velocity) and the degree of myelination surrounding neurons have been proposed as potentially important variables for individual differences in intelligence. This chapter discusses neuroimaging studies that include positron emission tomography (PET), magnetic resonance imaging (MRI), and parieto-frontal integration theory (P-FIT) model of intelligence to emphasize the importance of information flow. Structural neuroimaging studies with large samples continue to relate intelligence to brain development. A number of new functional imaging studies use sophisticated experimental designs to examine cognitive and psychometric components of intelligence. The combination of neuroimaging and genetic research is one of the most powerful new approaches to understanding the neural basis of intelligence. Studies show that regional gray matter and white matter are largely under genetic control and share common genes with intelligence.