You already know it’s hard to balance your checkbook while
simultaneously reflecting on your past. Now, investigators at the Stanford
University School of Medicine — having done the equivalent of wire-tapping a
hard-to-reach region of the brain — can tell us how this impasse arises.
The researchers showed that groups of nerve cells in a
structure called the posterior medial cortex, or PMC, are strongly activated
during a recall task such as trying to remember whether you had coffee
yesterday, but just as strongly suppressed when you’re engaged in solving a
math problem.