Zapping part of the brain makes you think harder – at a cost

Researchers at the University of Munich found that stimulating the dorsolateral prefrontal cortex, a region linked to motivation, improved performance on a difficult mental task. However, this improvement came with increased mental fatigue afterwards. The study involved 31 volunteers who underwent transcranial direct current stimulation (tDCS) while performing the 3-back memory test. Those who received tDCS reacted faster and more accurately than those who didn't, but also showed higher levels of the neurotransmitter glutamate in their dorsolateral prefrontal cortex. This suggests that mental fatigue may be caused by the buildup of glutamate, which can harm cells at high levels. The findings support the importance of taking breaks when feeling mentally tired.