There are multiple time scales synaptic plasticity happens on. For instance, ion channels can be moved in or out of the membrane to modulate excitability. On a

There are multiple time scales synaptic plasticity happens on. For instance, ion channels can be moved in or out of the membrane to modulate excitability. On a longer time scale, gene expression can change. Synaptic plasticity can get really complicated, but Kandel's book has some great chapters on mechanism.