Presynaptically expressed long-term depression at cerebellar parallel fiber synapses |
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Authors: | De-lai Qiu Thomas Kn?pfel |
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Institution: | (1) Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan |
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Abstract: | Plasticity at synapses between parallel fiber (PF) and Purkinje neurons (PN) is widely accepted as a cellular model for certain
forms of cerebellar learning. Although PF–PN synapses are known to express bidirectional long-term plasticity at the postsynaptic
site, long-term plasticity at the presynaptic site is currently limited to potentiation of the synapses. In this paper, we
report on presynaptically expressed PF long-term depression (preLTD) that is observed when presynaptically expressed PF long-term
potentiation (preLTP) is pharmacologically prevented. PF preLTD is most efficiently induced by 4 Hz PF stimulation and requires
activation of cannabinoid CB1 receptors. Our results indicate that, during preLTD induction, endocannabinoids are released
in an NMDA receptor-dependent, but not mGlu1 receptor-dependent, fashion. We conclude that bidirectional plasticity mechanisms
exist for both presynaptic and postsynaptic components of cerebellar learning. |
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Keywords: | Cerebellar parallel fiber Purkinje neuron GCaMP2 transgenic mouse Calcium transients Presynaptic LTD Cannabinoid CB1 receptor |
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