Naslov
Adult structure and development of the human fronto-opercular cerebral cortex (Broca`s region)

Autori
Cepanec, Maja ; Judaš, Miloš

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Neurologia Croatica / Ivkić, Goran ; Judaš, Miloš ; Klarica, Marijan ; Kostović, Ivica ; Šimić, Goran ; Petanjek, Zdravko - Zagreb, 2007, 114-115

Skup
Drugi hrvatski kongres neuroznanosti

Mjesto i datum
Zagreb, Hrvatska, 18.05.2007. - 19.05.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
frontal cortex ; Broca`s region ; cytoarchitectonics

Sažetak
Broca's area encompasses opercular and triangular part of the inferior frontal gyrus, covered by Brodmann's areas 44 and 45, respectively. Recent neuroimaging studies have revealed that, in addition to classical language functions, Broca's area has novel and unexpected functions, serving as a likely interface of action and perception important for both verbal and nonverbal communication. We focus on structural features of Broca's area in adult and developing human brain and note that: (a) in terms of architectonic classification, Broca's area displays a dual nature by virtue of its intermediate position between agranular motor-premotor cortex and granular prefrontal associative cortex ; and (b) numerous studies of morphological asymmetries are of limited value for understanding neurobiological basis of functions implemented by Broca's area. We also summarize findings from our ongoing study on prenatal and postnatal development of two defining cytoarchitectonic features of Broca's area in the adult brain, magnopyramidality (meaning that pyramidal neurons in layer III are larger than those in layer V) and dysgranularity (meaning that cortical layer IV is present, but poorly developed). We analyzed Nissl-stained and celloidin or paraffin embedded serial coronal sections of 35 human brains ranging in age from 8. postconceptional weeks to 15 postnatal years. The brains are part of extensive and versatila Zagreb Neuroembryological Collection and all material was obtained with the approval of Institutional Ethical Committee. We find that the fronto-opercular cortex in the newborn is still quite immature (e.g. still contains prominent granular layer IV as well as transient fetal subplate zone), and that defining architectonic features were still undeveloped during the first postnatal year, but gradually appear during the second (magnopyramidality) and third (dysgranularity) postnatal year. Thus, any claims on allegedly ascertained morphological and cytoarchitectonic asymmetry of frontal language-related regions in prenatal, perinatal and early postnatal period seem to be exaggerated and not supported by histological evidence. However, it should be noted that our data do not preclude the possibility that much earlier (even prenatal) areal differentiation could be discerned with use of markers for selective expression of genes which may be specific for cortical area, cortical layer or molecular subtype of pyramidal neurons. We conclude that areal specification of areas 44 and 45 requires at least 2 (and probably 3) years of postnatal life for its gradual completion ; the timing of this completion roughly coincides with the onset of full-fledged speech and language development. We currently perform a quantitative stereological analysis of magnopyramidality and dysgranularity in postnatal fronto-opercular region to pinpoint the onset and relative timing of these crucial architectonic parameters.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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