Theanine and Caffeine on Neurophysiology of Attention

L-theanine and caffeine are nutritional compounds that are naturally found in tea. Our recent findings using an EEG paradigm are consistent with the findings of others, indicating that intake of L-theanine and caffeine reduce the time needed for a person to differentiate between two visual stimuli and react to only one stimulus. In order to understand how these compounds give rise to these improvements, the investigators need to study how these compounds are related to various areas of the brain. To achieve this, the investigators plan to scan the brains of nine participants after they take either 1) L-theanine alone, 2) caffeine alone 3) the combination of both L-theanine and caffeine as compared with a placebo (distilled water), to see which has the greatest impact on attention and on regions in the brain that bring about attention.