Environmental Enrichment Duration Differentially Affects Behavior and Neuroplasticity in Adult Mice.

Marianne Leger, Eleni Paizanis, Kwamivi Dzahini, Anne Quiedeville, Valentine Bouet, Jean-Christophe Cassel, Thomas Freret, Pascale Schumann-Bard, Michel Boulouard
Cereb. Cortex. 2014-06-05; 25(11): 4048-4061
DOI: 10.1093/cercor/bhu119

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Leger M(1), Paizanis E(1), Dzahini K(2), Quiedeville A(1), Bouet V(1), Cassel JC(2), Freret T(1), Schumann-Bard P(1), Boulouard M(1).

Author information:
(1)Normandie Universités, Université de Caen Basse-Normandie, Groupe Mémoire et Plasticité Comportementale (GMPc), EA 4259, F-14032, Caen, France.
(2)Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, Université de Strasbourg, CNRS, Faculté de Psychologie, Groupe de Recherche NeuroMem 2905, 12 rue Goethe, F-67000 Strasbourg, France.

Environmental enrichment is a powerful way to stimulate brain and behavioral
plasticity. However the required exposure duration to reach such changes has not
been substantially analyzed. We aimed to assess the time-course of appearance of
the beneficial effects of enriched environment. Thus, different behavioral tests
and neurobiological parameters (such as neurogenesis, brain monoamines levels,
and stress-related hormones) were concomitantly realized after different
durations of enriched environment (24 h, 1, 3, or 5 weeks). While short
enrichment exposure (24 h) was sufficient to improve object recognition memory
performances, a 3-week exposure was required to improve aversive stimulus-based
memory performances and to reduce anxiety-like behavior; effects that were not
observed with longer duration. The onset of behavioral changes after a 3-week
exposure might be supported by higher serotonin levels in the frontal cortex, but
seems independent of neurogenesis phenomenon. Additionally, the benefit of 3-week
exposure on memory was not observed 3 weeks after cessation of enrichment. Thus,
the 3-week exposure appears as an optimal duration in order to induce the most
significant behavioral effects and to assess the underlying mechanisms.
Altogether, these results suggest that the duration of exposure is a keystone of
the beneficial behavioral and neurobiological effects of environmental


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