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Axon-carrying dendrites convey privileged synaptic input in hippocampal neurons
Christian Thome1, Tony Kelly2, Antonio Yanez3
1Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany; Bernstein Center for Computational Neuroscience (BCCN) Heidelberg/Mannheim, 69120 Heidelberg, Germany.
Neuron
|September 10, 2014
Summary
Hippocampal pyramidal cells often have axons originating from dendrites, not the soma. These axon-carrying dendrites (AcDs) are more efficient at generating action potentials, suggesting a privileged pathway for neuronal input.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Computational Neuroscience
Background:
- Neuronal processing traditionally involves dendritic input, somatic integration, and axonal output.
- The axon initial segment (AIS), crucial for action potential generation, is typically located on the soma.
Purpose of the Study:
- To investigate the origin of axons in hippocampal pyramidal cells.
- To compare the efficiency of synaptic input onto different dendritic compartments in eliciting action potentials.
Main Methods:
- Morphological analysis of hippocampal pyramidal cells.
- Multiphoton glutamate uncaging to study synaptic input and neuronal excitability.
- Electrophysiological recordings to assess action potential generation.
Main Results:
- Hippocampal pyramidal cell axons frequently originate from basal dendrites, not the soma, particularly in CA1.
- Axon-carrying dendrites (AcDs) exhibit lower activation thresholds for action potential generation compared to regular dendrites.
- AcDs demonstrate intrinsic hyperexcitability, producing dendritic spikes with higher probability and amplitude.
Conclusions:
- Axon-carrying dendrites represent a distinct and privileged pathway for excitatory synaptic input in hippocampal pyramidal cells.
- This alternative axonal origin influences neuronal integration and signal transmission within the hippocampus.
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