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Magnetic Field Projector for Deep Brain Stimulation

Deep brain stimulation (DBS) is an established surgical therapy for treatment of a number of neurological and neuropsychiatric disorders based on the modulation of neuronal firing deep in the brain. However, the delicate surgical operation and extremely expensive cost of the current DBS technology impede its wide applications. For non-invasive brain stimulation, transcranial magnetic stimulation and transcranial direct current stimulation have been tried in various therapeutic applications with little success due to two major imitations with their applied electromagnetic field: 1) the field does not focus on targeted brain functional sites, and 2) the field penetration depth is too shallow to be effective in stimulating targeted brain functional sites. In this paper, a novel magnetic field projector (MFP) capable of magnetically inducing deep brain modulation of neuronal firing is presented. The MFP projects a focused magnetic field to deep brain regions while suppressing the field on the scalp. The field penetration depth can be adjusted by configuring the structure parameters of the device as well as the excitation pulse current amplitude. An MFP prototype has been developed and tested on rats to modulate upward the neuronal firing frequency at the brain functional site ventrolateral preoptic nucleus for sleep induction, with the brain responses measured by EEG. The results showed that EEG sleep spindles were induced by a train of 9 Hz magnetic stimulation pulses for 10 s.