In Brief

Conventional wisdom advises us to keep a positive attitude. But new research from Washington University in St. Louis suggests that may not be so easy, since the interaction between mood and thinking is more complicated than previously believed.

Jeremy R. Gray, PhD, Todd S. Braver, PhD, and Marcus E. Raichle, MD, used functional magnetic resonance imaging to record activity in the lateral prefrontal cortex (PFC) of 14 college-age volunteers to see if their mood affected their cognitive abilities. For 10 minutes, participants either watched a short video that provoked a mild emotional state--amusement or anxiety--or one of two neutral documentaries. Then, for five minutes they worked on tests of short-term memory involving words or faces displayed on a computer screen. Participants tried to recall whether a particular word or face was the same as one shown three times back in the series.

As participants completed the verbal and nonverbal tasks, brain scans showed that activity in the lateral PFC was influenced by the combination of emotion and cognitive activity, but it wasn't affected by either one individually. "This brain region only cares about the pairing of an emotional state and the task," says Braver. "You can't call it an emotion region, you can't call it a cognition region. It really cares about what task you're doing and what mood you're in."

Another interesting finding was the crossover interaction between mood and behavior. While pleasant emotions heralded better performance on verbal tasks, participants in good moods actually did worse on the visual tasks. The reverse was true for negative or anxious moods: anxious participants did better on visual tasks and worse on the verbal tasks.

However, it's much too early to plan your entertainment based on how you want your brain to perform, Braver notes, since this study only tested cognitive activity in the five minutes after watching the video.

Next on the agenda? Besides checking if these results can be extrapolated into the long term, the researchers plan to investigate the introduction of personality as a variable. Preliminary research, Braver says, shows that brain activity during performance of some tasks thought to be purely cognitive can be predicted by features such as introversion and extroversion.

The research appeared in the March 19 Proceedings of the National Academy of Sciences (Vol. 99, No. 6).

--M. GREENGRASS