Figure 4.

Linearity in temporal and frequency space. (A) Injection of hyperpolarizing and depolarizing pulses in a cortical neuron patched in vivo, around resting membrane potential. The V-I relation indicated is roughly linear in this subthreshold range. (B) Sine waves of current with four different frequencies were injected simultaneously in a patched neuron in vivo (top, red curve). The voltage was recorded (top, blue curve). The modulus of the Fourier transform of both signals is shown here, as a function of frequency (Hz): current (red, A); voltage (blue, V). The frequencies corresponding to the peaks on both signals illustrate the linearity in frequency of the system, here tested between 1 and 1000 Hz. To see this figure in color, go online.