We thank Martin Raff, David Parkinson, Rhona Mirsky, and Kristjan Jessen for critical reading of the manuscript. “
“Environmental enrichment refers to housing conditions, where animals experience http://www.selleckchem.com/products/azd5363.html higher levels of sensory, motor, social, and cognitive stimuli compared to a normal cage environment (van Praag et al., 2000 and Nithianantharajah and Hannan, 2006). Enrichment has a

variety of effects on the brains of wild-type mice and rats at many levels, ranging from molecular and cellular to behavioral. At the cellular level, enrichment increases dendritic branching and length, as well as the number of dendritic spines and the size of synapses on some neuronal populations (Moser et al., 1994, Rampon et al., 2000a, Faherty et al., 2003 and Leggio et al., 2005). Furthermore, enrichment enhances hippocampal neurogenesis (Kempermann et al., 1997 and van Praag et al., 1999) and synaptogenesis (Rampon et al., 2000a, Gogolla et al., 2009 and Bednarek and Caroni, 2011). Many of these morphological changes CT99021 molecular weight are consistent with enrichment-induced alterations in the expression of genes

involved in synaptic function and neuroplasticity (Rampon et al., 2000b). Enrichment can increase levels of neurotrophins, such as brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), which play integral roles in neuronal signaling (Young et al., 1999 and Ickes et al., 2000). Enrichment

also increases the expression of synaptic proteins, such as the presynaptic vesicle protein, synaptophysin, and postsynaptic density-95 protein (PSD-95) (Nithianantharajah et al., 2004). At the behavioral level, enrichment induces learning enhancement in various behavioral tests (Kempermann et al., 1997 and Rampon et al., old 2000a), reduces memory decline in aged animals (Bennett et al., 2006), decreases anxiety, and increases exploratory activity (Benaroya-Milshtein et al., 2004). Furthermore, enrichment has beneficial effects on brain disorders, such as Huntington’s disease, Alzheimer’s disease, Parkinson’s disease, and various forms of brain injury (Nithianantharajah and Hannan, 2006). BDNF plays an important role in these enrichment-induced changes (Falkenberg et al., 1992 and Rossi et al., 2006); however, the precise mechanism of this action is not well understood. The kinesin superfamily proteins (KIFs) are microtubule-based molecular motors that transport membrane organelles, protein complexes, and messenger RNAs (mRNAs) (Hirokawa et al., 2009). KIFs have fundamental roles in neuronal function, plasticity, morphogenesis, and survival by transporting such cargos (Hirokawa et al., 2010). Intriguingly, recent reports have shown that some KIFs (KIF5 and KIF17) are implicated in learning and memory (Puthanveettil et al., 2008 and Yin et al., 2011).