It turns out that in the actively functioning cerebral cortex, intermediate metabolic products accumulate, which leads to fatigue. Fatigue signals us that we need to stop this activity in order to maintain the brain’s working capacity.
Scientists conducted experiments where they had to solve cognitive problems all day long. The first group solved easy problems, and the second – difficult ones. In volunteers, the brain was monitored using NMR spectroscopy.
Over time, participants in the second group began to show signs of accumulated fatigue and glutamic acid in the lateral regions of their brain’s prefrontal cortex. This makes it difficult for synapses to work: neurons have too little glutamate inside and too much outside. Thus, it becomes toxic to nerve cells.