Editing Synaptic plasticity (section)

===Long-term depression===
Brief activation of an excitatory pathway can produce what is known as long-term depression (LTD) of synaptic transmission in many areas of the brain. LTD is induced by a minimum level of postsynaptic depolarization and simultaneous increase in the intracellular calcium concentration at the postsynaptic neuron. LTD can be initiated at inactive synapses if the calcium concentration is raised to the minimum required level by heterosynaptic activation, or if the extracellular concentration is raised. These alternative conditions capable of causing LTD differ from the Hebb rule, and instead depend on synaptic activity modifications. [[D-serine]] release by [[astrocyte]]s has been found to lead to a significant reduction of LTD in the hippocampus.<ref name="Glia"/>
Activity-dependent LTD was investigated in 2011 for the electrical synapses (modification of Gap Junctions efficacy through their activity).<ref name="pmid22021860">{{cite journal | vauthors = Haas JS, Zavala B, Landisman CE | title = Activity-dependent long-term depression of electrical synapses | journal = Science | volume = 334 | issue = 6054 | pages = 389–93 | date = October 2011 | pmid = 22021860 | doi = 10.1126/science.1207502 | bibcode = 2011Sci...334..389H | s2cid = 35398480 | pmc = 10921920 }}</ref> In the brain, cerebellum is one of the structures where LTD is a form of neuroplasticity.<ref>{{cite journal | vauthors = Mitoma H, Kakei S, Yamaguchi K, Manto M | title = Physiology of Cerebellar Reserve: Redundancy and Plasticity of a Modular Machine | journal = Int. J. Mol. Sci. | volume = 22 | pages = 4777 |  date = April 2021 | issue = 9 | doi = 10.3390/ijms22094777 | pmid = 33946358 | pmc = 8124536 | doi-access = free }}</ref>