A magnetic field projector for deep brain modulation

Deep brain stimulation (DBS) is an established surgical therapy for treatment of a number of neurological and neuropsychiatric disorders based on the deep brain neural network modulation. However, the delicate surgical operation and high cost impede its wide applications. For non-invasive brain stimulation, transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been applied in various therapeutic applications with little success due to the in-principle very limited field penetration depth and unable to be point focused. In this paper a novel magnetic field projector (MFP) capable of magnetically inducing deep brain modulation of neuronal firing is presented. The MFP allows the magnetic field to project to deep brain regions while suppressing the field strength 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. A MFP prototype has been developed and tested on rats to modulate the firing rate of the brain sleep promoting site ventrolateral preoptic nucleus (VLPO). Electroencephalogram (EEG) signals recorded on scalp showed that sleep spindles can be induced by a train of 9 Hz magnetic stimulation pulses within 10 seconds.