Introduction
The molecular basis of learning and memory involves modifying neuronal synapses in response to electrical activity, a process termed synaptic plasticity. Memory formation has been divided into two temporal phases. Short-term memory formation involves changes to synaptic efficacy by modifying existing proteins. Long-term memory formation requires new gene transcription and protein production to stabilize recent changes. These long-term changes to synaptic strength take several forms. In long-term potentiation(LTP), specific synapses are strengthened. In long-term depression (LTD), specific synapses are weakened. In homeostatic plasticity, neuron-wide shifts in responsiveness maintain the maximal sensitivity of the neuron to future activity-dependent synaptic plasticity.