Visualization of corticofugal projections during early cortical development in a tau-GFP-transgenic mouse.

TitleVisualization of corticofugal projections during early cortical development in a tau-GFP-transgenic mouse.
Publication TypeJournal Article
Year of Publication2007
AuthorsJacobs, EC, Campagnoni C, Kampf K, Reyes SD, Kalra V, Handley V, Xie Y-Y, Hong-Hu Y, Spreur V, Fisher RS, Campagnoni AT
JournalThe European journal of neuroscience
Volume25
Issue1
Pagination17-30
Date Published2007 Jan
ISSN0953-816X
KeywordsAnimals, Animals, Newborn, Brain Mapping, Cell Count, cerebral cortex, Embryo, Mammalian, Gene Expression Regulation, Developmental, Green Fluorescent Proteins, Immunohistochemistry, In Situ Hybridization, Mice, Mice, Transgenic, Nerve Tissue Proteins, Neural Pathways, Neurons, tau Proteins
Abstract

The first postmitotic neurons in the developing neocortex establish the preplate layer. These early-born neurons have a significant influence on the circuitry of the developing cortex. However, the exact timing and trajectory of their projections, between cortical hemispheres and intra- and extra-cortical regions, remain unresolved. Here, we describe the creation of a transgenic mouse using a 1.3 kb golli promoter element of the myelin basic protein gene to target expression of a tau-green fluorescent protein (GFP) fusion protein in the cell bodies and processes of pioneer cortical neurons. During embryonic and early neonatal development, the timing and patterning of process extension from these neurons was examined. Analysis of tau-GFP fluorescent fibers revealed that progression of early labeled projections was interrupted unexpectedly by transient pauses at the corticostriatal and telencephalic-diencephalic boundaries before invading the thalamus just prior to birth. After birth the pioneering projections differentially invaded the thalamus, excluding some nuclei, e.g. medial and lateral geniculate, until postnatal days 10-14. Early labeled projections were also found to cross to the contralateral hemisphere as well as to the superior colliculus. These results indicate that early corticothalamic projections appear to pause before invading specific subcortical regions during development, that there is developmental regulation of innervation of individual thalamic nuclei, and that these early-generated neurons also establish early projections to commissural and subcortical targets.

DOI10.1002/glia.22336
Alternate JournalEur. J. Neurosci.