דיכוי סינפטי ארוך-טווח

Long-term depression, or LTD, is a process of synaptic weakening that occurs over time between pre- and postsynaptic neuronal connections.

One mechanism by which LTD occurs is dependent on the amount of calcium ions flowing into the postsynaptic neuron after presynaptic stimulation. Low calcium concentration due to infrequent presynaptic stimulation can initiate a signaling cascade that culminates in the endocytosis or removal of AMPA glutamate receptors from the membrane. As a result, the postsynaptic response to the same sporadic presynaptic stimulation is further weakened.

Thus, LTD is important for learning, since unused or rarely used synapses are weakened and can even be pruned away, freeing up resources and space that can be used by the neuron for other functions, such as LTP strengthening of more important synapses.