From the weekly What's New:
fMRI devices, which image the regions of activity in the brain, are making many important discoveries. None are more important to WN than an Austrian study reported this week at a meeting of the Radiological Society in Chicago. A significant increase in activity in the anterior cingulate cortex of the brain, which is responsible for short-term memory, peaked 20 minutes after consuming caffeine corresponding to two cups of coffee. The effect dissipates after 45 minutes. By my calculation, sipping coffee at the rate of 3 cups an hour should sustain the effect indefinitely. I just have to remember to keep sipping.