High resolution

Module 10: Figure coincidence detectors

The function of neuronal coincident detectors in hippocampal neurons and cerebellar Purkinje cells.

In the case of the hippocampal neuron on the left, the coincident detector is the N-methyl-D-aspartate (NMDA) receptor that responds to membrane depolarization (ΔV) of the postsynaptic membrane (input 1) and glutamate from the presynaptic ending (input 2). The Ca2+ that enters then activates Ca2+/calmodulin-dependent protein kinase II (CaMKII), which phosphorylates the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor, resulting in long-term potentiation. In the Purkinje neuron on the right, the coincident detector is the inositol 1,4,5-trisphosphate receptor (IP3R), which responds to Ca2+ derived from the depolarization (ΔV) induced by the climbing fibre (CF; input 1) and IP3 generated in response to glutamate stimulation from the parallel fibres (input 2). The Ca2+ then activates calcineurin (CaN) and protein phosphatase 1 (PP1), which dephosphorylates the AMPA receptor, resulting in long-term depression (LTD).