On the Initiation and Propagation of Dendritic Spikes in CA1 Pyramidal Neurons

Under certain conditions, regenerative voltage spikes can be initiated locally in the dendrites of CA1 pyramidal neurons. These are interesting events that could potentially provide neurons with additional computational abilities. Using whole-cell dendritic recordings from the distal apical trunk an...

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Bibliographic Details
Published in:The Journal of neuroscience 2004-12, Vol.24 (49), p.11046-11056
Main Authors: Gasparini, Sonia, Migliore, Michele, Magee, Jeffrey C
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Cellular/Molecular
Dendrites - physiology
Electrodes
Excitatory Postsynaptic Potentials - physiology
In Vitro Techniques
Ion Channels - physiology
Models, Neurological
Pyramidal Cells - physiology
Pyramidal Cells - ultrastructure
Rats
Rats, Sprague-Dawley
Receptors, AMPA - physiology
Receptors, N-Methyl-D-Aspartate - physiology
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Summary:Under certain conditions, regenerative voltage spikes can be initiated locally in the dendrites of CA1 pyramidal neurons. These are interesting events that could potentially provide neurons with additional computational abilities. Using whole-cell dendritic recordings from the distal apical trunk and proximal tuft regions and realistic computer modeling, we have determined that highly synchronized and moderately clustered inputs are required for dendritic spike initiation: approximately 50 synaptic inputs spread over 100 mum of the apical trunk/tuft need to be activated within 3 msec. Dendritic spikes are characterized by a more depolarized voltage threshold than at the soma [-48 +/- 1 mV (n = 30) vs -56 +/- 1 mV (n = 7), respectively] and are mainly generated and shaped by dendritic Na+ and K+ currents. The relative contribution of AMPA and NMDA currents is also important in determining the actual spatiotemporal requirements for dendritic spike initiation. Once initiated, dendritic spikes can easily reach the soma, but their propagation is only moderately strong, so that it can be modulated by physiologically relevant factors such as changes in the V(m) and the ionic composition of the extracellular solution. With effective spike propagation, an extremely short-latency neuronal output is produced for greatly reduced input levels. Therefore, dendritic spikes function as efficient detectors of specific input patterns, ensuring that the neuronal response to high levels of input synchrony is a precisely timed action potential output.
ISSN:0270-6474
1529-2401
DOI:10.1523/JNEUROSCI.2520-04.2004