Local Dendritic Activity Sets Release Probability at Hippocampal Synapses

The arrival of an action potential at a synapse triggers neurotransmitter release with a limited probability, p r . Although p r is a fundamental parameter in defining synaptic efficacy, it is not uniform across all synapses, and the mechanisms by which a given synapse sets its basal release probabi...

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Bibliographic Details
Published in:Neuron (Cambridge, Mass.) Mass.), 2008-08, Vol.59 (3), p.475-485
Main Authors: Branco, Tiago, Staras, Kevin, Darcy, Kevin J., Goda, Yukiko
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Animals, Newborn
CELLBIO
Cells, Cultured
Confidence intervals
Dendrites - metabolism
Dendrites - ultrastructure
Electric Stimulation - methods
Excitatory Postsynaptic Potentials - physiology
Excitatory Postsynaptic Potentials - radiation effects
Hippocampus - cytology
Image Processing, Computer-Assisted
Microscopy
Microscopy, Electron, Transmission
Models, Neurological
Neurons
Neurons - cytology
Patch-Clamp Techniques
Probability
Pyridinium Compounds - metabolism
Quaternary Ammonium Compounds - metabolism
Rats
SIGNALING
Software
Synapses - metabolism
Synapses - ultrastructure
SYSNEURO
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Summary:The arrival of an action potential at a synapse triggers neurotransmitter release with a limited probability, p r . Although p r is a fundamental parameter in defining synaptic efficacy, it is not uniform across all synapses, and the mechanisms by which a given synapse sets its basal release probability are unknown. By measuring p r at single presynaptic terminals in connected pairs of hippocampal neurons, we show that neighboring synapses on the same dendritic branch have very similar release probabilities, and p r is negatively correlated with the number of synapses on the branch. Increasing dendritic depolarization elicits a homeostatic decrease in p r , and equalizing activity in the dendrite significantly reduces its variability. Our results indicate that local dendritic activity is the major determinant of basal release probability, and we suggest that this feedback regulation might be required to maintain synapses in their operational range.
ISSN:0896-6273
1097-4199
DOI:10.1016/j.neuron.2008.07.006