RC's Which Increases Cognition?

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I am interested in researching RC's which are able of increasing cognition, and "opening" the mind to understanding numerics better. For example, some people may look at an equation in a calculus book and will be able to quickly grasp the concept and application of a calculus equation; while other people wont grasp the equation, if ever, in a very long span of time. So the chemical would have to be capable of inducing improvements on this part of the brain, which is the "left brain."

I am not looking for vitamins or nutrients for the brain, but more so, chemicals which are able to evidently increase activity in this certain part of the brain. The chemical would ideally be legal and not under any restrictions. So, has anyone ever had any experiences with chemicals which had similar effects or would suggest a chemical which is capable of achieving such a result?