Lateralization of choline acetyltransferase (ChAT) activity in fetus and adult human brain.

Choline acetyltransferase (ChAT) activity was measured in the first temporal gyrus (Brodmann area 22) and in the gyrus precentrale (Brodmann area 4) of both hemispheres in post-mortem human fetus and adult brains. In fetal brains the ChAT values were higher in the right first temporal gyrus in comparison to the left one (P less than 0.05). Conversely in adult brains ChAT activity was higher in the left first temporal gyrus than in the controlateral one (P less than 0.05). Absolute values of ChAT were similar in the right first temporal gyrus of fetus and adult brains. No asymmetry was found in the fetal and adult gyrus precentrale. These findings could be interpreted in terms of differential rates of development of cholinergic synapses in left and right human temporal lobes.