Geometric mapping of electrical activation.

<p><b>A</b>, Response probability color coded activation maps for different stimulation amplitudes showing a clear correlation between stimulation amplitude and number of activated neurons (scale bar 50 µm). <b>B</b>, Proportion of activated neurons as a function of stimulation amplitude, indicating a saturation zone. <b>C</b>, Recordings incorporating stimulations from different electrodes provide insight regarding mechanism of electrical stimulation. Each electrode activates a unique set of neurons with a very small neuronal population that responds to both.