Voluntary physical exercise promotes ocular dominance plasticity in adult mouse primary visual cortex

Abstract

Ocular dominance (OD) plasticity in the mouse primary visual cortex (V1) declines during aging and is absent beyond postnatal day (P) 110 when mice are raised in standard cages (SCs; Lehmann and Lo¨wel, 2008). In contrast, raising mice in an enriched environment (EE) preserved a juvenile-likeODplasticity into late adulthood (Greifzu et al., 2014).EEraising provides the mice withmoresocial interactions, voluntary physical exercise, and cognitive stimulation compared with SC, raising the question whether all components are needed or whether one of them is already sufficient to prolong plasticity. To test whether voluntary physical exercise alone already prolongs the sensitive phase for OD plasticity, we raised mice from 7 d before birth to adulthood in slightly larger than normal SCs with or without a running wheel (RW). When the mice were older than P135, we visualized V1 activity before and after monocular deprivation (MD) using intrinsic signal optical imaging. Adult RW-raised mice continued to show an OD shift toward the open eye after 7 d of MD, while age-matched SC mice without a RWdid not show OD plasticity. Notably, running just during the7dMDperiod restored OD plasticity in adult SC-raised mice. In addition, theODshift of theRWmice was mediated by a decrease of deprived-eye responses in V1, a signature of “juvenile-like” plasticity. We conclude that voluntary physical exercise alone is sufficient to promote plasticity in adult mouse V1.