what is the postsynaptic density
The postsynaptic density (PSD) is a protein dense specialization attached to the postsynaptic membrane.PSDs were originally identified by electron microscopy as an electron-dense region at the membrane of a postsynaptic neuron.he structure and composition of the PSD have been the focus of numerous molecular studies of synaptic plasticity, a cellular model of learning and memory. PSDs are sized on the order of 250 to 500 nanometres in diameter and 25 to 50 nanometres in thickness, depending on the activity state of the synapse.