Elsevier

Experimental Gerontology

Volume 60, December 2014, Pages 1-11
Experimental Gerontology

Brief dark exposure restored ocular dominance plasticity in aging mice and after a cortical stroke

https://doi.org/10.1016/j.exger.2014.09.007Get rights and content
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Highlights

  • Dark exposure restored ocular dominance (OD) plasticity in adult and aging mice.

  • Dark exposure protected from lesion-induced impairments of OD-plasticity

  • Restored OD-plasticity was prevented by increasing intracortical inhibition.

  • Dark exposure reduced the numbers of parvalbumin+-cells and perineuronal nets.

  • Dark exposure is a promising tool to restore and preserve plasticity in aging brains.

Abstract

In the primary visual cortex (V1), monocular deprivation (MD) induces a shift in the ocular dominance (OD) of binocular neurons towards the open eye (Wiesel and Hubel, 1963; Gordon and Stryker, 1996). In V1 of C57Bl/6J mice, this OD-plasticity is maximal in juveniles, declines in adults and is absent beyond postnatal day (PD) 110 (Lehmann and Löwel, 2008) if mice are raised in standard cages. Since it was recently shown that brief dark exposure (DE) restored OD-plasticity in young adult rats (PD70-100) (He et al., 2006), we wondered whether DE would restore OD-plasticity also in adult and old mice and after a cortical stroke. To this end, we raised mice in standard cages until adulthood and transferred them to a darkroom for 10–14 days. Using intrinsic signal optical imaging we demonstrate that short-term DE can restore OD-plasticity after MD in both adult (PD138) and old mice (PD535), and that OD-shifts were mediated by an increase of open eye responses in V1. Interestingly, restored OD-plasticity after DE was accompanied by a reduction of both parvalbumin expressing cells and perineuronal nets and was prevented by increasing intracortical inhibition with diazepam. DE also maintained OD-plasticity in adult mice (PD150) after a stroke in the primary somatosensory cortex. In contrast, short-term DE did not affect basic visual parameters as measured by optomotry. In conclusion, short-term DE was able to restore OD-plasticity in both adult and aging mice and even preserved plasticity after a cortical stroke, most likely mediated by reducing intracortical inhibition.

Abbreviations

DE
dark exposure
EE
enriched environment
LR
light reared
MD
monocular deprivation
OD
ocular dominance
ODI
ocular dominance index
PD
postnatal day
PNN
perineuronal net
PT
photothrombosis
PV
parvalbumin
S1
primary somatosensory cortex
SC
standard cage
V1
primary visual cortex

Keywords

Visual cortex
Dark exposure
Ocular dominance plasticity
Monocular deprivation
Optical imaging
Photothrombosis
Intracortical inhibition
Aging

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