Impedance Tools

These tools plot various functions of Impedance vs location and frequency. ImpShape is described below, but see also:

Each tool has three panels: The top panel contains button and menu controls specific to the tool. The middle panel displays a picture of the cell and marks the measurement and injection sites. The bottom panel displays the results of the impedance measurements.

The redraw button in the top panel forces a re-calculation of the results. This is useful if a parameter or state changes in the underlying model of the cell. The Extras ‣ MovieMode menu item recalculated the results for each step during a InitRun. When selected, the Extras ‣ AutoScale rescales the results panel after each calculation.

The Plot menu specifies whether to plot log attenuation (default), input impedance, transfer impedance, or V(measure)/V(inject) Note: log attenuation is defined as ln( V(inject)/V(measure) ) Input impedance is plotted with respect to the measurement site and the injection site is unused.

ImpShape

Tool for generating the neuromorphic rendering, a picture of the neuron in which distance is scaled to represent the log of voltage attenuation. In this transform, long distance represents large attenuation.

The tool consists of three panels. The middle panel shows the normal unscaled shape of the neuron on which the user can select a measurement/injection site (default location is location 0 of the currently accessed section when the ImpShape object was created). The lower panel displays a neuromorphic rendering along with a unit attenuation scale bar. The upper control panel allows selection of the frequency at which to calculate the impedance and the direction of current flow, Vin/Vout, with respect to the measurement/injection site.

When Vin is selected one can imagine that for every point on the cell, that point is voltage clamped to 1 mV and the voltage at the measurement site (0 end of the selected section in the lower panel) is recorded. The shape of the neuron is then plotted so that the distance between the voltage clamp site and the measurement site is the natural log of the attenuation factor, ln( V(inject)/V(measure) )

When Vout is selected, one can imagine that the selected position becomes voltage clamped to 1mV and the voltage at every other position on the cell is measured.

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