Electrophysiology: electrode compensation

The electrophysiology library also contains methods to compensate for the electrode voltage in single-electrode current clamp recordings. To import the electrophysiology library:

from brian.library.electrophysiology import *

There is a series of example scripts in the examples/electrophysiology folder.

Active Electrode Compensation (AEC)

The electrophysiology library includes the Active Electrode Compensation (AEC) technique described in Brette et al (2008), High-resolution intracellular recordings using a real-time computational model of the electrode, Neuron 59(3):379-91.

Given a digital current-clamp recording of the (uncompensated) potential v (vector of values) and injected current i, the following instructions calculate the full kernel of the system and the electrode kernel:


ksize is the size of the full kernel (number of sampling steps; typical size is about 15 ms) and start_tail is the size of the electrode kernel (start point of the ‘’tail’’ of the full kernel; typical size if about 4 ms). The electrode should be compensated for capacitance (capacitance neutralization) but not resistance (bridge compensation). The best choice for the input current is a series of independent random values, and the last ksize steps of v should be null (i.e., the injection should stop before the end). Here it was assumed that the recording was done at the soma; if it is done in a thin process such as a dendrite or axon, the function electrode_kernel_dendrite should be used instead. The full kernel can also be obtained from a step current injection:


where i is a constant value in this case (note that this is not the best choice for real recordings).

Once the electrode kernel has been found, any recording can be compensated as follows:


where v is the raw voltage recording, i is the injected current and ke is the electrode kernel.

Lp compensation

The Lp compensation is an other electrode compensation method. It is based on linear model fitting of an electrode and a neuron in response to an injected current. The fitness function is the Lp error between the full model response and the raw trace, with p<2 to minimize the bias due to the nonlinear voltage excursions of action potentials.

You can use it like this:

Vcomp, params = Lp_compensate(I, Vraw, .1*ms)

where I is the injected current, Vraw is the raw voltage trace, and the last parameter is the inverse of the sampling frequency. I and Vraw must be 1D Numpy arrays with the same length. The Lp_compensate function returns the compensated trace Vcomp and the best parameters params, which is a 2D Numpy array where each column contains the parameters R, tau, Vr, Re, taue. Columns correspond to consecutive slices of the current and the voltage, the compensation is performed independently on each slice. The duration of the slices can be specified with the slice_duration keyword argument. Also, the p parameter can also be specified as a keyword argument.

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