Green tea supplements increase resilience to emotional distractions in an interval timing task

Green tea extracts have been shown to increase activity in prefrontal cortex, with possible beneficial effects on memory and attentional performance. To further probe the impact of green tea supplements on memory and attention, we examined the effect of a green tea flavonoid-rich extract on interval timing with emotional distracters. The presentation of task-irrelevant emotional distracters during a timing task has been shown to delay interval timing behavior. In a previous study in our lab we found that local infusion of antidepressants into medial prefrontal cortex (homologuos to the human frontal lobe) decreases the timing delay after emotional distracters (Matthews et al. Frontiers in Integrative Neuroscience 2012). Therefore, we hypothesized that exposure to green tea flavonoid-rich extracts would decrease the timing delay after emotional distracters. In our study, male C57BL6 mice were divided into three groups: Mice in the SHOCK and SHOCK-GTE conditions received pairings of the distracter stimulus with a mild footshock, while mice in the NO-SHOCK condition did not. For the following two weeks, mice in the SHOCK-GTE condition received free access to a 2% solution of green tea extract (Polyphenon60, Sigma) in water, while the other mice received free access to tap water in their home cages. During this interval, all mice were trained in a peak-interval procedure. Mice were then tested by unexpectedly presenting the distracter stimulus during the peak-interval test. Mice in the NO-SHOCK condition delayed minimally after the distracter, while mice in the SHOCK condition delayed reliably more, consistent with previous findings in our lab. Instead, mice in the SHOCK-GTE condition showed reliably less delay than SHOCK mice, not different from the NO-SHOCK mice, suggesting that consumption of the green tea extract increased resilience to emotionally-charged distracters. These findings suggest that green tea flavonoid-rich extract might have beneficial effects on working memory following emotional distraction