  This paper investigates the efficacy of high frequency switched-mode neural
stimulation. Instead of using a constant stimulation amplitude, the stimulus is
switched on and off repeatedly with a high frequency (up to 100kHz) duty cycled
signal. By means of tissue modeling that includes the dynamic properties of
both the tissue material as well as the axon membrane, it is first shown that
switched-mode stimulation depolarizes the cell membrane in a similar way as
classical constant amplitude stimulation. These findings are subsequently
verified using in vitro experiments in which the response of a Purkinje cell is
measured due to a stimulation signal in the molecular layer of the cerebellum
of a mouse. For this purpose a stimulator circuit is developed that is able to
produce a monophasic high frequency switched-mode stimulation signal. The
results confirm the modeling by showing that switched-mode stimulation is able
to induce similar responses in the Purkinje cell as classical stimulation using
a constant current source. This conclusion opens up possibilities for novel
stimulation designs that can improve the performance of the stimulator
circuitry. Care has to be taken to avoid losses in the system due to the higher
operating frequency.
