Some while ago Daedalus proposed the use of pulsed magnetic fields in psychotherapy. Unlike electro-shock therapy, they induce purely local currents in the brain. The technique now seems to be maturing. It is claimed that pulsed magnetic fields, applied to specific regions of the brain, can affect motor control or relieve depression. So Daedalus is now sharpening the selectivity of the method, and extending it to the nervous system as a whole.
A tightly shaped magnetic pulse will induce current in, and therefore fire, nerves in quite a small region of tissue. By itself, this might not be useful; even a narrow nerve trunk can carry thousands of individual fibres, each with a different destination. But Daedalus feels that each fibre must have its own ‘resonant frequency’, possibly quite broad, at which it will fire most effectively. It may also respond best to a specific shape of pulse. So if magnetic pulses of carefully adjusted frequency, amplitude and shape are aimed at a nerve trunk, they should trigger just one class of fibre (those to a specific muscle, say) without affecting the rest.
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