NEURON Tutorial #13

Goals: Develop an integrated environment to test one Ih model.

Specific Aims:

Develop an integrated environment for the following measurements.
- Membrane time constant.
- Input resistance.
- Rebound slope.
- Temporal summation.
- Impedance magnitude profile.
- Voltage lag (phase).
- GV curve.
- Activation time constant.
- Deactivation time constant.
Test Sonia's Ih model (J.Neurosci. 24:11046-11056 (2004)).

Downloads:

Alpha.hoc - For temporal summation experiment (alpha EPSCs)
Chirp.hoc - For chirp experiment
ExperimentControl.hoc - Experiment contols
Fitting.hoc - Procedures for curve fitting
GraphVI.hoc - Voltage and current graphs
Main.hoc - Program start here
ParameterControl.hoc - Parameter controls
Pulse.hoc - For pulse experiment (membrane time connstant)
RunControl.hoc - Run controls
Step.hoc - For current step experiment (Rin, sag, rebound slope)
VoltageClamp.hoc - Voltage clamp experiment
13.zip - Contains all files.

Steps and Notes:

Let's check Sonia's Ih. Parameters: e_h = -30 mV Temperature = 33 °C Start "Main.hoc".
Measure membrane time constant:embrane time constant:
Click "Pulse (1 ms)" button. Click "Initiate & Run" button. The parameters: gbar_h = 2.15e-5 e_pas = -70 With this set of parameters, the resting membrane potential is hyperpolarized. To have a resting potential at -65 mV, change gbar_h to 4e-5 and you will have the resting membrane potential at -65 mV. The assumption is that when Ih is blocked, the membrane potential hyperpolarizes by 5 mV.	Voltage and Current Traces (gbar_h = 2.15e-5)	Voltage and Current Traces (gbar_h = 4e-5)
Click "Fit Decay" button.	Tau = 24.3 (ms)
Measure Rin and Rebound Slope:
Click "Current Step (500 ms)" button. Click "Run Step Family" button. Click "Measure Rin (LR)" button. Click "Measure Rebound Slope (LR)" button.	Voltage and Current Traces:	Rin = 56.9 (M Ohm) (Linear Regression) Rebound Slope = -0.17 (mV/mV) (Linear Regression)
Temporal Summation:
Click "Five Alpha EPSCs (20 Hz)" button. Click "Initiate & Run" button. Click "Measure Temporal Summation" button.	Temporal Summation = 11.0 (%)
Chirp Experiment:
Click "Chirp" button. Click "Initiate & Run" button. Click "Characterize Chirp Response" button. Click "Fit Impedance Amplitude" button. Click "Plot Voltage Lag"	Voltage and Current Traces:	Impedance Amplitude: Depolarizing Resonance Frequency = 3.5 (Hz) Hyperpolarizing Resonance Frequency = 4.5 (Hz) Voltage Lag:
Voltage Clamp Experiment:
Click "Voltage Clamp" button. Click "Run Activation Step Family" button. Click "Fit GV Curve" button.	Voltage and Current Traces:	GV Curve: Vhalf = -81.1 (mV) k = 7.90 (mV)
Click "Run Deactivation Step Family" button. Click "Plot Tau" button.	Voltage and Current Traces:	Tau: