Podcast
Questions and Answers
What type of recording is represented if the scale bar shows currents in pA or nA?
What type of recording is represented if the scale bar shows currents in pA or nA?
In an I-V plot for Na+, what happens when the membrane potential is at 80 mV?
In an I-V plot for Na+, what happens when the membrane potential is at 80 mV?
When plotting the I-V relationship for a leak K+ channel, what feature characterizes its curve?
When plotting the I-V relationship for a leak K+ channel, what feature characterizes its curve?
What is the behavior of Kv channels in relation to the membrane potential?
What is the behavior of Kv channels in relation to the membrane potential?
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What must be true about Eion when plotting the I-V relationship for ions?
What must be true about Eion when plotting the I-V relationship for ions?
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Study Notes
Current Clamp vs. Voltage Clamp Recordings
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Current clamp records the membrane potential (Vm) of a neuron while injecting a constant current.
- Traces in current clamp recordings show action potentials (APs), excitatory postsynaptic potentials (EPSPs), and inhibitory postsynaptic potentials (IPSPs).
- Scale bars for current clamp traces are in mV.
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Voltage clamp records the current flowing across the membrane while holding the Vm at a constant value.
- Traces show currents.
- Scale bars for voltage clamp traces are in pA or nA.
I-V Plot
- An I-V plot is a graph showing the relationship between current (y-axis) and voltage (x-axis).
- The reversal potential (Eion) of an ion is the voltage at which there is no net current flow for that ion. This is where the I-V curve crosses the x-axis.
- To determine the direction of current for a given voltage:
- Positive current: The ion moves out of the cell.
- Negative current: The ion moves into the cell.
Leak K+ Channels vs. Voltage-Gated K+ (Kv) Channels
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Leak K+ channels are always open and contribute to the resting membrane potential.
- I-V plot: Linear; inward current at voltages below -80 mV (EK).
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Voltage-gated K+ (Kv) channels open in response to membrane depolarization.
- I-V plot: Not linear; no inward current below -50 mV. The current gradually increases as Vm becomes more depolarized due to sequential activation of voltage sensors in the channel.
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Description
This quiz explores the differences between current clamp and voltage clamp techniques used in neuroscience. It covers how each method records neuronal activity and the significance of I-V plots in understanding ion behavior and reversal potentials. Test your knowledge on these fundamental concepts in electrophysiology!
