Maturational changes in diffusion anisotropy in the rat corpus callosum: Comparison with quantitative histological evaluation

Abstract

Purpose: To determine the main histological components that affect fractional anisotropy (FA) in postnatal development of the rat corpus callosum and compare FA values with histological changes evaluated quantitatively. Materials and Methods:Diffusion tensor image (DTI) data of the rat (postnatal 1-10 weeks) corpus callosum were obtained with a 7.0 T MR scanner. Histological parameters were quantitatively assessed in toluidine blue-stained semithin sections. Simple and multiple linear regression analyses were performed to investigate relationships between FA values and histological variables. Results:The mean FA value (mFA) increased significantly in the early growth stages, whereas the change became smaller after postnatal week 4. Simple regression analysis showed a high correlation between the area of myelin sheath and mFA (r ϭ 0.856; P Ͻ 0.01). The area of extracellular space correlated negatively with mFA (r ϭ Ϫ0.813; P Ͻ 0.01). In a forward stepwise analysis, the area of myelin sheath had the strongest influence on mFA (P Ͻ 0.001), followed by the number of unmyelinated axons (P ϭ 0.113). Multiple linear regression analysis revealed that both parameters predicted mFA with a highly significant adjusted correlation coefficient (r 2 adj. ϭ 0.738, P Ͻ 0.001). Conclusion:During the early development stage in the rat corpus callosum, the strongest contribution to FA value is the area of myelin sheath.

Functional correlates of central white matter maturation in perinatal period in rabbits

“…This observation confirm human DTI studies (Sadeghi et al, 2013) suggesting that FA is more related to fiber density than to myelination in CC. In contrast to rabbit and human data, the increase of myelinated fibers contents in CC between 2 and 4 postnatal weeks was the best predictor of FA growth in rats (Jito et al, 2008). Such differences in FA and maturation development can be attributed to the difference between species.…”

“…Maturation of DTI indices continues is rabbits during at least four postnatal weeks (D'Arceuil et al, 2005). Similar, rapid phase of FA change between P12 and P24 coincides with the onset of active myelination in rats (Calabrese and Johnson, 2013; Jito et al, 2008). In kittens, this period occurs between second and fourth weeks (Baratti et al, 1999).…”

Noninvasive MRI Measures of Microstructural and Cerebrovascular Changes During Normal Swine Brain Development

“…Correspondence between swine and human FA changes during maturation is supported by previous invasive studies that suggest a similar pattern of myelination and cellular development exists in both species (21,23). That FA changes are likely attributed to myelination is based on a previous study showing that myelin sheath area was most strongly correlated with FA during development (24). However, other processes of neural development may also affect properties of water diffusion.…”

Functional Development of Large-Scale Sensorimotor Cortical Networks in the Brain

“…Responses start in the contralateral S1 area with a large current sink in layer IV, presumably generated by depolarization of the cortical neurons targeted by TC terminals already functionally connected during the first days of life (Catalano et al, 1991;Tenke et al, 1993;Peterson et al, 1995;Molnár et al, 2003;Khazipov et al, 2004;Kichula and Huntley, 2008). Decreasing onset latency with age reflects the maturation of subcortical (Shoykhet and Simons, 2008) and TC pathways including the myelination process, which is almost undetectable during the first week but increases rapidly during the second and third weeks (Fields, 2005;Jito et al, 2008).…”