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Distance-dependent homeostatic synaptic scaling mediated by a-type potassium channels
Hiroshi T Ito1, Erin M Schuman
1Division of Biology, California Institute of Technology Pasadena, CA, USA.
Frontiers in Cellular Neuroscience
|January 16, 2010
Summary
A-type potassium channels help maintain the gradient of synaptic strength along CA1 pyramidal neuron dendrites. Inhibiting these channels alters synaptic plasticity and AMPA receptor distribution, impacting neuronal computation.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Synaptic Plasticity
Background:
- Synaptic efficacy in CA1 pyramidal neurons increases with dendritic distance from the cell body.
- Activity-dependent synaptic plasticity dynamically modulates individual synapse strength.
- A-type potassium channels exhibit a proximal-to-distal gradient along dendrites, suggesting a role in coordinating synaptic changes.
Purpose of the Study:
- To investigate the role of A-type potassium channels in maintaining the proximal-to-distal gradient of synaptic strength.
- To explore how homeostatic plasticity interacts with channel distribution to regulate synaptic efficacy.
Main Methods:
- Activity blockade using tetrodotoxin combined with A-type potassium channel inhibition.
- Electrophysiological recordings of miniature excitatory postsynaptic current (mEPSC) frequency in CA1 somata and dendrites.
- Measurement of AMPA receptor density in different dendritic strata.
Main Results:
- A-type potassium channel inhibition for 12 hours significantly increased mEPSC frequency in CA1 somata but not in dendritic recordings.
- AMPA receptor density increased in stratum pyramidale but remained unchanged in stratum radiatum.
- These findings suggest a role for A-type potassium channels in regulating AMPA receptor distribution.
Conclusions:
- Differential distribution of A-type potassium channels creates a membrane potential gradient along apical dendrites.
- This gradient regulates AMPA receptor distribution, thereby controlling synaptic strength.
- A-type potassium channels are crucial for maintaining neuronal computational capacity by regulating dendritic synaptic strength gradients.
Related Concept Videos
01:19The Role of Ion Channels in Neuronal Computation
A postsynaptic neuron usually receives numerous impulses from several other presynaptic neurons. The axon hillock of the postsynaptic neuron integrates all these signals and determines the likelihood of firing an action potential.
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.
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.
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...
At rest, the K+ is the main ion that moves across the membrane through...
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...
At rest, the K+ is the main ion that moves across the membrane through...
01:21The Resting Membrane Potential
Overview
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
01:26Chemical Synapses
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...