Dendrodendritic synaptic signals in olfactory bulb granule cells: local spine boost and global low-threshold spike

Egger, V., Svoboda, K., Mainen, Z. F. (April 2005) Dendrodendritic synaptic signals in olfactory bulb granule cells: local spine boost and global low-threshold spike. J Neurosci, 25 (14). pp. 3521-30. ISSN 1529-2401 (Electronic)

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DOI: 10.1523/jneurosci.4746-04.2005


In the mammalian olfactory bulb, axonless granule cells process synaptic input and output reciprocally within large spines. The nature of the calcium signals that underlie the presynaptic and postsynaptic function of these spines is mostly unknown. Using two-photon imaging in acute rat brain slices and glomerular stimulation of mitral/tufted cells, we observed two forms of action potential-independent synaptic Ca2+ signals in granule cell dendrites. Weak activation of mitral/tufted cells produced stochastic Ca2+ transients in individual granule cell spines. These transients were strictly localized to the spine head, indicating a local passive boosting or spine spike. Ca2+ sources for these local synaptic events included NMDA receptors, voltage-dependent calcium channels, and Ca2+-induced Ca2+ release from internal stores. Stronger activation of mitral/tufted cells produced a low-threshold Ca2+ spike (LTS) throughout the granule cell apical dendrite. This global spike was mediated by T-type Ca2+ channels and represents a candidate mechanism for subthreshold lateral inhibition in the olfactory bulb. The coincidence of local input and LTS in the spine resulted in summation of local and global Ca2+ signals, a dendritic computation that could endow granule cells with subthreshold associative plasticity.

Item Type: Paper
Uncontrolled Keywords: Action Potentials physiology Animals Animals Newborn Calcium metabolism Dendrites physiology Dose-Response Relationship Radiation Electric Stimulation methods Excitatory Postsynaptic Potentials physiology Neurons cytology physiology Olfactory Bulb cytology Patch-Clamp Techniques methods Rats Rats Sprague-Dawley Synapses physiology
Subjects: Investigative techniques and equipment > electrophysiology
organs, tissues, organelles, cell types and functions > tissues types and functions > olfactory bulb
Investigative techniques and equipment > microscopy > flourescence microscopy > two-photon excitation microscopy
CSHL Authors:
Communities: CSHL labs > Mainen lab
CSHL labs > Svoboda lab
Depositing User: CSHL Librarian
Date: 6 April 2005
Date Deposited: 13 Jan 2012 16:25
Last Modified: 03 May 2018 15:16
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