On the use of caffeine as a contrast booster for BOLD fMRI studies.

This study explored the possible use of caffeine as an agent to improve the BOLD (blood oxygen level-dependent) signal response in fMRI. Previous research has demonstrated that caffeine has the ability to reset the level of coupling between blood flow and neuronal activity. In the present study, it has been shown that caffeine causes a decrease in cerebral perfusion by as much as 13.2% without a change in performance. Caffeine is a cerebral vasoconstrictor that causes an increase in the concentration of deoxyhemoglobin and thus a decrease in the BOLD baseline resting signal by 4.4%. During activation, the vasculature responds from below-normal baseline levels with a normal increase in blood flow and volume, resulting in an overall increase in the BOLD contrast. This increase can be as large as 22-37% during the performance of a visually cued motor task. The benefit of such a large increase in the BOLD contrast could be used to improve the image resolution, the acquisition scheme, or the task design of fMRI experiments. Caffeine has the potential to be used as a contrast booster for fMRI experiments.