The arrows indicate peak gray matter volume in prefrontal cortex. You can see that that peak happens a couple of years later in boys relative to girls, and that's probably because boys go through puberty a couple of years later than girls on average, and then during adolescence, there's a significant decline in gray matter volume in prefrontal cortex.
Strelice pokazuju vrhunac obujma sive tvari u prefrontalnom korteksu. Možete vidjeti da se taj vrh kod dječaka pojavljuje nekoliko godina kasnije u odnosu na djevojčice, vjerojatno zbog toga što dječaci kasnije prolaze kroz pubertet nego djevojčice, u prosjeku, te da tijekom adolescencije  postoji značajno smanjenje u obujmu sive tvari u prefrontalnom korteksu.