Postnatal changes in cytoarchitectonic asymmetry of Broca's region

Surprisingly little is known about the development of cortical language organization in children, Lesions of the dominant hemisphere before age five to seven may shift language representation to the previously non-dominant side, those after this time rarely change the side of speech representation (I). Failure to develop left-hemispheric asymmetry is suggested to be critical in stuttering (2). Previous studies of our own group have shown interhemispheric differences in cytoarchitecture of Broca’s region (areas 44 and 45) in adults which may underlie left-hemispheric dominance (3). It was shown that cytoarchitectonic asymmetry of the primary motor cortex changes during postnatal development (4). Neither the onset of structural asymmetry in Broca’s region nor its postnatal modification are known. Therefore, we analyzed whether microstructural asymmetry changes during postnatal ontogeny in areas 44 and 45.