Rearrangement of Retinogeniculate Projection Patterns after Eye-Specific Segregation in Mice

Abstract

It has been of interest whether and when the rearrangement of neuronal circuits can be induced after projection patterns are formed during development. Earlier studies using cats reported that the rearrangement of retinogeniculate projections could be induced even after eye-specific segregation has occurred, but detailed and quantitative characterization of this rearrangement has been lacking. Here we delineate the structural changes of retinogeniculate projections in the C57BL/6 mouse in response to monocular enucleation (ME) after eye-specific segregation. When ME was performed after eye-specific segregation, rearrangement of retinogeniculate axons in the dorsal lateral geniculate nucleus (dLGN) was observed within 5 days. Although this rearrangement was observed both along the dorsomedial-ventrolateral and outer-inner axes in the dLGN, it occurred more rapidly along the outer-inner axis. We also examined the critical period for this rearrangement and found that the rearrangement became almost absent by the beginning of the critical period for ocular dominance plasticity in the primary visual cortex. Taken together, our findings serve as a framework for the assessment of phenotypes of genetically altered mouse strains as well as provide insights into the mechanisms underlying the rearrangement of retinogeniculate projections.

Retinal Input Regulates the Timing of Corticogeniculate Innervation

“…In contrast, the removal of the ipsilateral eye results in an ϳ8% net loss, which seems insufficient to affect cortical innervation. It is also conceivable that disrupting the process of eye-specific segregation could be a contributing factor, because early postnatal ME leads to the expansion of retinal projections from the spared eye (Lund et al, 1973;So et al, 1978;Manford et al, 1984;Hayakawa and Kawasaki, 2010); however, this seems unlikely because segregation is interrupted in both hemispheres by ME but only the hemisphere, which incurs the greatest loss of retinal input, seems affected.…”

“…Such a perturbation not only reduces the total amount of retinal input to dLGN, but also disrupts the recession of uncrossed retinal projections, because ME leads to an expansion of projections from the spared eye (Lund et al, 1973;So et al, 1978;Manford et al, 1984;Hayakawa and Kawasaki, 2010). Figure 8A shows examples of coronal sections through both hemispheres of dLGN at P3 and P7 after ME at birth.…”

In vivo genetic manipulation of cortical progenitors in gyrencephalic carnivores using in utero electroporation

“…Immunohistochemistry was performed as described previously with slight modifications (Matsubayashi et al, 2008; Hayakawa and Kawasaki, 2010). Sections were made using a cryostat, permeabilized with 0.1–0.5% Triton X-100/PBS, and incubated overnight with primary antibodies, which included anti-Sox2 antibody (R&D Systems), anti-Pax6 antibody (Covance), anti-Tbr2 antibody (Abcam) and anti-neurofilament-M antibody (Chemicon).…”

Distinct developmental principles underlie the formation of ipsilateral and contralateral whisker-related axonal patterns of layer 2/3 neurons in the barrel cortex

“…Immunohistochemistry was performed as described previously with slight modifications Hayakawa and Kawasaki, 2010). Briefly, animals were deeply anesthetized with pentobarbital and transcardially perfused with 4% paraformaldehyde.…”