engleski

Postnatal maturation of large layer IIIc pyramidal neurons in human associative cortex

We studied development of the large layer IIIC cortico-cortical magnopyramidal neurons (L3N) in the dorsolateral prefrontal cortex (dlPFC) of 125 human specimens ranging from premature infants up to 91 years old. Quantitative Golgi data of L3N development were correlated with Nissl and immunocytochemical staining. Timing of developmental events of L3N was compared with pattern of development for the subclass of layer V projection neurons (L5N) and with appearance of higher cognitive functions of dlPFC. L3N showed a unique biphasic dendritic growth (Petanjek et al., Cerebral Cortex. Access published July 25, 2007. doi:10.1093/cercor/bhm124), where the first stage is intensive perinatal dendritic differentiation. After a “ dormant” period during infancy, a second large dendritic elongation occurred around the age of 2y, which is followed by appearance of specific cellular pattern at the age of 4-5y. Dendritic development for L5N appears in a linear pattern just within infancy and do not elongate later on, in contrast to the L3N. In addition, the spine development on L3N dendrites showed both the highest and the most protracted dendritic spine overproduction (presumably glutamatergic synapses) until 20-25y of age. Therefore, the final synaptic and dendritic maturation for L3N do not occur before the age of 20-25y. Experimental data and neuro-pathological findings showed that L3N are key elements of circuitry involved in processing higher associative cognitive functions of dlPFC, like conceptual understanding of mind and other complex human specific social relations. Interestingly, development of this cognition level occurred mostly during early childhood, after the age of 2y, and is protracted up to late adolescence (20-25y) when final cognitive and emotional maturation is reached. In conclusion, it seems that selective maturation of L3N is principally connected with changes in cognition development after infancy.

associative cortex; cognitive functions; development; human

nije evidentirano