How can long-term habituation change the structure of a synapse?

In the context of neuroplasticity, long-term habituation involves structural modifications to the synapse that reduce the efficacy of neural communication. While short-term habituation is often associated with functional changes—such as the closing of calcium channels and a subsequent decrease in neurotransmitter release—long-term habituation can lead to physical alterations in the synaptic architecture.1

Specifically, research into simple model organisms like the marine snail Aplysia has demonstrated that long-term habituation results in a reduction in the number of active zones at nerve terminals. By decreasing these active sites, the nervous system effectively limits the capacity for signal transmission, contributing to the long-term decline in the behavioral response to a repeated, non-threatening stimulus. This process illustrates the brain's fundamental capacity to reorganize its connections in response to experience, a core principle of neuroplasticity.123