Long-term depression (LTD), in neurophysiology, is the weakening of a neuronal synapse that lasts from hours to days. It results from either strong synaptic stimulation (as occurs in the cerebellar Purkinje cells) to persistent weak synaptic stimulation (as in the hippocampus). LTD is thought to result from changes in postsynaptic receptor density, although changes in presynaptic release may also play a role. Cerebellar LTD has been hypothesized to be important for motor learning. However, it is likely that other plasticity mechanisms play a role as well. Hippocampal LTD may be important for the clearing of old memory traces.

See also

• Long-term potentiation

Neurophysiology