Throughout life the brain maintains a remarkable potential to reorganize in response to experience and environmental changes and to compensate for brain damage or neurological disorders (Sanes and Donoghue, 2000). To achieve this level of flexibility, the brain needs to be able to up-and down-regulate synaptic activity while keeping a relatively stable equilibrium of activity over time. The term synaptic plasticity refers to up-and down-regulation in direct response to external stimuli whereas homeostatic plasticity describes regulatory processes guaranteeing stable levels of synaptic activity over time. Metaplasticity refers to the malleability of plasticity (synaptic or non-synaptic) by prior activity (Abraham, 2008).