The front page of today's Chicago Tribune has a report from the annual meeting of the Radiological Society of North America (RSNA) on The tall and the short of why caffeine works:
Now a team of Austrian researchers using advanced brain imaging technology has discovered that caffeine makes people more alert by perking up part of the brain involved in short-term memory, the kind that helps focus attention on the tasks at hand.
... The findings revealed increased activity in the frontal lobe, where working memory is centered, and the anterior cingulum, which controls attention, in volunteers after they consumed 100 milligrams of caffeine, the equivalent of about two cups of coffee. These areas showed no increased activity when the subjects drank the same fluid without caffeine.
[Conference brief on the work: Influence of Caffeine Excess on Activation Patterns in Verbal Working Memory]
This is the work of Dr. Florian Koppelstaetter of the Medical University Innsbruck in Austria. Now, what was I doing? Right, more coffee.
Note: if the original article is behind a registration wall, it appears to be reprinted at the Orlando Sentinel and there is a similar report at the CBS News site, Caffeine May Boost Memory.