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Neuron. 2014 Sep 17;83(6):1418-30. doi: 10.1016/j.neuron.2014.08.013. Epub 2014 Sep 4.

Axon-carrying dendrites convey privileged synaptic input in hippocampal neurons.

Author information

1
Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany; Bernstein Center for Computational Neuroscience (BCCN) Heidelberg/Mannheim, 69120 Heidelberg, Germany.
2
Laboratory for Cognition Research and Experimental Epileptology, Department of Epileptology, University of Bonn, 53127 Bonn, Germany.
3
Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany.
4
Institute of Neuroanatomy, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany.
5
Institute for Anatomy and Cell Biology, Heidelberg University, 69120 Heidelberg, Germany.
6
Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany; Bernstein Center for Computational Neuroscience (BCCN) Heidelberg/Mannheim, 69120 Heidelberg, Germany. Electronic address: alexei.egorov@urz.uni-heidelberg.de.

Abstract

Neuronal processing is classically conceptualized as dendritic input, somatic integration, and axonal output. The axon initial segment, the proposed site of action potential generation, usually emanates directly from the soma. However, we found that axons of hippocampal pyramidal cells frequently derive from a basal dendrite rather than from the soma. This morphology is particularly enriched in central CA1, the principal hippocampal output area. Multiphoton glutamate uncaging revealed that input onto the axon-carrying dendrites (AcDs) was more efficient in eliciting action potential output than input onto regular basal dendrites. First, synaptic input onto AcDs generates action potentials with lower activation thresholds compared with regular dendrites. Second, AcDs are intrinsically more excitable, generating dendritic spikes with higher probability and greater strength. Thus, axon-carrying dendrites constitute a privileged channel for excitatory synaptic input in a subset of cortical pyramidal cells.

PMID:
25199704
DOI:
10.1016/j.neuron.2014.08.013
[Indexed for MEDLINE]
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