CNET News.com says habitual activity (e.g., smoking, eating fatty foods, gambling, etc.) changes neural activity patterns in a specific region of the brain when habits are formed. These neural patterns created by habit can be changed or altered. But when a stimulus from the old days returns, the dormant pattern can reassert itself, according to a new study from the M.I.T., putting an individual in a neural state akin to being on autopilot... The neural patterns get established in the basal ganglia, a brain region critical to habits, addiction and procedural learning.