Abstract
For routine behavioral tasks, mice predominantly rely on olfactory cues and tactile information. In contrast, their visual capabilities appear rather restricted, raising the question whether they can improve if vision gets more behaviorally relevant. We therefore performed long-term training using the visual water task (VWT): adult standard-cage raised mice were trained to swim towards a rewarded grating stimulus so that using visual information avoided excessive swimming towards non-rewarded stimuli. Indeed, and in contrast to old mice raised in a generally enriched environment (Greifzu et al., 2016), long-term VWT-training increased visual acuity (VA) on average by more than 30% to 0.82cyc/deg. In an individual animal, VA even increased to 1.49cyc/deg, i.e. beyond the rat range of VAs.
Since visual experience enhances the spatial frequency threshold of the optomotor reflex of the open eye after monocular deprivation (MD), we also quantified monocular vision after VWT-training. Monocular VA did not increase reliably and eye reopening did not initiate a decline to pre-MD values as observed by optomotry; VA-values rather increased by continued VWT-training. Thus optomotry and VWT measure different parameters of mouse spatial vision.
Finally, we tested whether long-term MD induced ocular dominance (OD) plasticity in the visual cortex of adult (P162-182) standard-cage raised mice. This was indeed the case: 40-50d of MD induced OD-shifts towards the open eye in both VWT-trained and, surprisingly, also in age-matched mice without VWT-training.
These data indicate that i) long-term VWT-training increases adult mouse VA, and ii) long-term MD induces OD-shifts also in adult standard-cage raised mice.
Significance Statement Usually, mice predominantly rely on olfactory and tactile cues. We here show that visual capabilities of mice can markedly improve if vision becomes more behaviorally relevant: Long-term vision training in the visual water task (VWT) increased mouse visual acuity by >30%. Moreover, a direct comparison of VWT-determined visual acuity with optomotry-determined spatial frequency threshold of the optomotor response revealed that these two behavioral tests measure different parameters of mouse spatial vision. Finally, we report that long-term monocular deprivation could induce ocular dominance plasticity in the visual cortex of old standard cage-raised mice. Overall, our data suggest that long-term changes in sensory input can boost sensory processing and induce plastic changes even at an advanced age.
Footnotes
Authors report no conflict of interest.
This work was supported by the Federal Ministry of Education and Research, Germany, Grants 01GQ0810 (to S.L.) and by a grant of the Deutsche Forschungsgemeinschaft through the Collaborative Research Center 889 “Cellular Mechanisms of Sensory Processing” (Project B5 to S.L.).
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
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