Related Experiment Video
Updated: Jul 11, 2026
16:38
Dual Electrophysiological Recordings of Synaptically-evoked Astroglial and Neuronal Responses in Acute Hippocampal Slices
Published on: November 26, 2012
Astrocyte membrane responses and potassium accumulation during neuronal activity
Julian P Meeks1, Steven Mennerick
1Program in Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Hippocampus
|September 14, 2007
Summary
Astrocytes faithfully sense neuronal activity-induced potassium increases, but do not significantly buffer extracellular potassium during brief stimulation, challenging older theories of spatial buffering.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Glial Biology
Background:
- Astrocytes were historically considered potassium electrodes, depolarizing with neuronal activity.
- Recent findings suggest astrocyte depolarization is linked to glutamate transport, questioning their role in sensing potassium.
Purpose of the Study:
- To investigate stimulus-evoked currents in hippocampal astrocytes.
- To determine the fidelity of astrocytes in sensing extracellular potassium rises and their role in spatial buffering.
Main Methods:
- Whole-cell recordings from hippocampal CA1 astrocytes.
- Measurement of stimulus-evoked currents, including glutamate transporter and potassium currents.
- Assay of excitatory postsynaptic currents (EPSCs) and fiber volleys to assess neuronal function.
Main Results:
- Hippocampal astrocytes exhibited stimulus-evoked glutamate transporter currents and barium-sensitive inward rectifier potassium (K(ir)) currents.
- Astrocyte depolarization predicted small extracellular potassium increases, suggesting potential for spatial buffering.
- Barium application did not significantly alter resting extracellular potassium or neuronal function, indicating limited K(ir) influence on synaptic transmission.
Conclusions:
- Hippocampal astrocytes are accurate sensors of extracellular potassium fluctuations.
- There is minimal evidence for significant astrocyte spatial potassium buffering during brief neuronal activity bursts.
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01:41Action Potentials
Overview
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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Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
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.
Membrane potential in neurons
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Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...
01:15Resting Potential Decay
The resting membrane potential of a neuron (-70mV) is sustained due to the selective ion permeability of the membrane. At the resting potential, the membrane is slightly permeable to ions like sodium (Na+) and chloride (Cl−) and highly permeable to potassium ions (K+). Differences in the ions' concentration inside the cell compared to the outside are maintained by membrane transport proteins like channels and pumps.
At rest, the K+ is the main ion that moves across the membrane through...
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01:24Resting Membrane Potential
The relative difference in electrical charge, or voltage, between the inside and the outside of a cell membrane, is called the membrane potential. It is generated by differences in permeability of the membrane to various ions and the concentrations of these ions across the membrane.
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Sometimes a single EPSP is strong enough to induce an action potential in the postsynaptic neuron. However, multiple presynaptic inputs must often create EPSPs around the same time for the postsynaptic neuron to be sufficiently depolarized to fire an action potential.
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