Cytoarchitectonic parameters of developmental capacity of the human associative auditory cortex during postnatal life.

In order to determine the developmental capacity of the human auditory cortex we studied the 'regressive' cytoarchitectonic events during perinatal and postnatal development: disappearance of fetal elements and cytoarchitectonic reorganization. Studies were done on Nissl-stained serial sections of human temporal cortex in the specimens ranging from 24 weeks of gestation to the 3rd postnatal year. The fetal layers were regularly found in the newborn in the posterior associative auditory cortex. The fetal subplate zone disappeared gradually over the first 3 postnatal months, indicating decline in the growth of the major cortical fibre systems. The fetal types of neurons have been found however also in older specimens in the associative auditory cortex. The auditory cortex also contains in the postnatal period some fetal elements which indicate the presence of prolonged anatomical developmental plasticity.