First discovery of long-term depression?
The process of long-term depression (LTD) was first discovered in the cerebellum by Ito et al. in 1982:

Ito M, Kano M. Long-lasting depression of parallel fiber-Purkinje cell transmission induced by conjunctive stimulation of parallel fibers and climbing fibers in the cerebellar cortex. Neurosci Lett. 1982;33(3):253-8

Ito M, Sakurai M and Tongroach P. Climbing fibre induced depression of both mossy fibre responsiveness and glutamate sensitivity of cerebellar Purkinje cells. Journal of Physiology 1982; 324: 113–134.

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