He believes the problem does not lie in how the brain is structured, but relates to how different regions of the brain are connected to each other. A region of the brain called the superior longitudinal fasciculus (SLF) connects the brain’s frontal lobe with the parietal lobe. In people with IED, the white matter in the SLF has less density and integrity than in people with other psychiatric disorders and healthy individuals. The white matter is the brain’s natural wiring between the lobes.