Calcium microdomains in aspiny dendrites.
Dendritic spines receive excitatory synapses and serve as calcium compartments, which appear to be necessary for input-specific synaptic plasticity. Dendrites of GABAergic interneurons have few or no spines and thus do not possess a clear morphological basis for synapse-specific compartmentalization. We demonstrate using two-photon calcium imaging that activation of single synapses on aspiny dendrites of neocortical fast spiking (FS) interneurons creates highly localized calcium microdomains, often restricted to less than 1 microm of dendritic space. We confirm using ultrastructural reconstruction of imaged dendrites the absence of any morphological basis for this compartmentalization and show that it is dependent on the fast kinetics of calcium-permeable (CP) AMPA receptors and fast local extrusion via the Na+/Ca2+ exchanger. Because aspiny dendrites throughout the CNS express CP-AMPA receptors, we propose that CP-AMPA receptors mediate a spine-free mechanism of input-specific calcium compartmentalization.
Goldberg
Jesse H
JH
Department of Biological Sciences, Columbia University, New York, NY 10027, USA. jhg24@columbia.edu
Tamas
Gabor
G
Aronov
Dmitriy
D
Yuste
Rafael
R
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D020013:Calcium Signaling / Q000502:physiology*; D002451:Cell Compartmentation / Q000502:physiology; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D007395:Interneurons / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008959:Models, Neurological; D019579:Neocortex / Q000502:physiology* / Q000648:ultrastructure; D018091:Receptors, AMPA / Q000502:physiology*; D019831:Sodium-Calcium Exchanger / Q000502:physiology; D013570:Synaptic Membranes / Q000502:physiology / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology
D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D018091:Receptors, AMPA; D019831:Sodium-Calcium Exchanger; D002118:Calcium