The Timing Is Right for Cerebellar Learning Conor Dempsey, Nathaniel B. Sawtell  Neuron  Volume 92, Issue 5, Pages 931-933 (December 2016) DOI: 10.1016/j.neuron.2016.11.039 Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 1 Delayed Plasticity Correctly Adjusts Synapses Responsible for Erroneous Motor Output when Error Signals Are Delayed (A) A standard timing-dependent plasticity rule in which near-coincident activation of climbing fiber (CF) and parallel fiber (PF) inputs cause synaptic depression of the PF synapses onto Purkinje cells (dashed line) and a delayed rule as reported by Suvrathan et al. (2016) in which PF activity that precedes a CF spike by an appropriate delay causes depression. (B) Before plasticity, granule cell activity (dark blue lines) sum to determine the simple spike firing rate of a Purkinje cell (green). Elevated firing from baseline causes, after a motor delay, an undesired eye movement (black), which in turn causes, after a sensory delay, an error signal carried by the CF (orange). (C) Dashed lines indicate changes due to the standard timing-dependent rule. PF inputs coincident with the CF are depressed, but because of motor and sensory delays, this does not correct the Purkinje cell firing that caused the erroneous eye movement. Solid lines indicate changes due to an appropriately delayed learning rule. Because the learning rule offset is matched to the sum of motor and sensory delays, only PF inputs whose firing precedes the CF by the total delay are depressed. This depression corrects the erroneous Purkinje cell firing, which in turn corrects the erroneous eye movement. Neuron 2016 92, 931-933DOI: (10.1016/j.neuron.2016.11.039) Copyright © 2016 Elsevier Inc. Terms and Conditions