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Real-time Electrophysiology: Using Closed-loop Protocols to Probe Neuronal Dynamics and Beyond
Published on: June 24, 2015
Interneurons hyperpolarize pyramidal cells along their entire somatodendritic axis
Lindsey L Glickfeld1, J David Roberts, Peter Somogyi
1Department of Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0634, USA.
Nature Neuroscience
|November 26, 2008
Summary
Rat hippocampal interneurons primarily inhibit pyramidal cells, causing hyperpolarization. This inhibitory effect on pyramidal cells occurs regardless of where synapses are located on the neuron.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Synaptic Plasticity
Background:
- GABAergic interneurons are the primary source of synaptic inhibition in the brain.
- Activation of GABA(A) receptors can paradoxically lead to neuronal excitation in certain contexts.
- The precise role of interneuron synaptic location in modulating pyramidal cell activity remains incompletely understood.
Purpose of the Study:
- To investigate the net effect of individual hippocampal interneurons on pyramidal cell membrane potential.
- To determine if synaptic location along the somato-dendritic axis influences the inhibitory or excitatory outcome of GABAergic input.
Main Methods:
- Utilized a noninvasive electrophysiological approach to monitor the impact of single interneuron activation.
- Recorded population activity of pyramidal cells in the rat hippocampus.
- Mapped synaptic connections from interneurons to specific compartments of pyramidal cells.
Main Results:
- Individual rat hippocampal interneurons consistently hyperpolarized pyramidal cells.
- This inhibitory effect was observed irrespective of whether synapses were located on the soma, axon initial segment, or dendrites.
- The findings challenge the notion that GABAergic input universally leads to excitation in specific neuronal compartments.
Conclusions:
- Hippocampal interneurons exert a predominantly hyperpolarizing influence on pyramidal cells.
- Synaptic targeting along the somato-dendritic axis does not alter the fundamental inhibitory nature of this interneuron-pyramidal cell interaction.
- This study clarifies the functional role of GABAergic inhibition in hippocampal circuits.
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01:14Action Potential
Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
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01:41Action Potentials
Overview
02:47The Synapse
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01:28Integration of Synaptic Events
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