By Amanda Gardner HealthDay Reporter by Amanda Gardner healthday Reporter – Fri Feb 26, 5:03 pm ET FRIDAY, Feb. 26 (HealthDay News) -- It's not a particular brain region that makes someone smart or not smart. Nor is it the strength and speed of the connections throughout the brain or such features as total brain volume. Instead, new research shows, it's the connections between very specific areas of the brain that determine intelligence and often, by extension, how well someone does in life. "General intelligence actually relies on a specific network inside the brain, and this is the connections between the gray matter , or cell bodies, and the white matter , or connecting fibers between neurons," said Jan Glascher, lead author of a paper appearing in this week's issue of the Proceedings of the National Academy of Sciences . "General intelligence relies on the connection b...