Part 3: Experimentation3
One of the cornerstones of Cognitive Neuroscience is curiously rooted in (or, perhaps, a phantom made real as the two are not scientifically linked) Phrenology. Phrenology held that different regions of the brain were responsible for different behaviors, and if one "exercised" these areas, it would cause the cranium to expand in those places and cause bumps. Phrenologists used calipers of extraordinary precision to map these bumps. Of course, the theory was roundly debunked, but today we have a robust scientific model for brain regions and their different functions.
Much of what we know of these is from studying what cognitive functions become impaired by damage to these regions. Of course, it is a better experimental design to intentionally cause lesions in a brain in specific areas and to similar brains than it is to wait for a stroke patient or someone with a brain tumor of a specific size and location to come along to fill in the gaps. To this end, we cannot use human patients for lesion studies (unethical), and resort to animals (merely unscrupulous) in almost all cases.