NEURON Tutorial #21

Goals: Examine The Properties of Fourier Transform of Chirp Current and Voltage Response


  1. Current and voltage traces.
  2. Fourier transform of current trace.
  3. Fourier transform of voltage trace.
  4. Impedance magnitude, impedance phase, and voltage lag.


e_pas = -65 (mV)
gbar_h = 0 (S/cm2)


1. Current and voltage traces

Baseline in voltage is removed.

Current Voltage

2. Fourier Transform of Current Trace

Current Magnitude

Current's Phase Unwrapped

3. Fourier Transform of Voltage Trace

Voltage's Magnitude

Voltage's Phase Unwrapped

4. Impedance Magnitude, Impedance Phase, and Voltage Lag


It is surprising that the magnitude profiles of current's and voltage's Fourier transform are zigzag, but the profile of impedance magnitude is smooth!
Another surprising finding is that the impedance phase is small at lower frequency, but the voltage lag is large there.

Impedance Magnitude

Impedance Phase Voltage lag