β-Adducin Is Required for Stable Assembly of New Synapses and Improved Memory upon Environmental Enrichment

Learning is correlated with the assembly of new synapses, but the roles of synaptogenesis processes in memory are poorly understood. Here, we show that mice lacking beta-Adducin fail to assemble new synapses upon enhanced plasticity and exhibit diminished long-term hippocampal memory upon environmental enrichment. Enrichment-enhanced the disassembly and assembly of dynamic subpopulations of synapses. Upon enrichment, stable assembly of new synapses depended on the presence of beta-Adducin, disassembly involved beta-Adducin phosphorylation through PKC, and both were required for augmented learning. In the absence of beta-Adducin, enrichment still led to an increase in spine structures, but the assembly of synapses at those spines was compromised. Virus-mediated re-expression of beta-Adducin in hippocampal granule cells of beta-Adducin(-/-) mice rescued new synapse assembly and learning upon enrichment. Our results provide evidence that synapse disassembly and the establishment of new synapses are both critically important for augmented long-term learning and memory upon environmental enrichment.