Abstract
Diffusion tensor imaging (DTI) is a technique that non-invasively provides quantitative measures of water translational diffusion, including fractional anisotropy (FA), that are sensitive to the shape and orientation of cellular elements, such as axons, dendrites and cell somas. For several neurodevelopmental disorders, histopathological investigations have identified abnormalities in the architecture of pyramidal neurons at early stages of cerebral cortex development. To assess the potential capability of DTI to detect neuromorphological abnormalities within the developing cerebral cortex, we compare changes in cortical FA with changes in neuronal architecture and connectivity induced by bilateral enucleation at postnatal day 7 (BEP7) in ferrets. We show here that the visual callosal pattern in BEP7 ferrets is more irregular and occupies a significantly greater cortical area compared to controls at adulthood. To determine whether development of the cerebral cortex is altered in BEP7 ferrets in a manner detectable by DTI, cortical FA was compared in control and BEP7 animals on postnatal day 31. Visual cortex, but not rostrally adjacent non-visual cortex, exhibits higher FA than control animals, consistent with BEP7 animals possessing axonal and dendritic arbors of reduced complexity than age-matched controls. Subsequent to DTI, Golgi-staining and analysis methods were used to identify regions, restricted to visual areas, in which the orientation distribution of neuronal processes is significantly more concentrated than in control ferrets. Together, these findings suggest that DTI can be of utility for detecting abnormalities associated with neurodevelopmental disorders at early stages of cerebral cortical development, and that the neonatally enucleated ferret is a useful animal model system for systematically assessing the potential of this new diagnostic strategy.
Highlights
Diffusion tensor imaging (DTI) studies have shown that in several neurological disorders, affected individuals possess white matter (WM) that is characterized by abnormally low fractional anisotropy (FA) in water diffusion
We found that bilateral enucleation at P7 induces marked changes in the overall distribution of callosal connections in visual cortex
These results suggest that DTI measurements at early developmental stages are capable of detecting abnormalities in neuropil development induced by neonatal enucleation
Summary
Diffusion tensor imaging (DTI) studies have shown that in several neurological disorders, affected individuals possess white matter (WM) that is characterized by abnormally low fractional anisotropy (FA) in water diffusion (see reviews by Lim and Helpern, 2002; White et al, 2008). In the immature cerebral cortex, water diffusion is highly anisotropic due to the influence of a different set of cellular structures (e.g., apical dendrites, undifferentiated dendrites, and axons) than those that influence water diffusion within WM at maturity (e.g., myelinated axons). Apical dendrites of pyramidal neurons are aligned perpendicular to the pial surface, and these selectively impose restrictions in directions parallel to the pial surface (Neil et al, 1998; McKinstry et al, 2002).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
