**Author details**

dopants dramatically reduces the magnetic field strength required to alter capacitance [28]. Therefore, a composite of magnetic particles and liquid crystals (as discussed above) might be able to convert a changing externally applied magnetic field into local electrical stimulation.

**Figure 8.** Spintronic particle writing to single neuron. Top: neuro-modulation in vital mouse brain slice (red) when spintronic nano-oscillator (STNO) particle is triggered by RF signal. Bottom: neuronal frequency changes in as a function

As discussed above, spintronic particles have been used to convert low-frequency electrical currents into high-frequency radio-frequency emissions. Our group successfully reversed this process, to convert applied radio-frequency (RF) radiation into low-frequency electrical currents that were able to affect the firing frequency of a single neuron (**Figure 8**) [35]. An attractive potential application of this technology is that the efficiency of conversion of the RF radiation exhibits frequency dependence that is also a function of the ambient magnetic field. This mechanism would permit spintronic devices to be addressed with micron-level spatial resolution.

Magnetic neuroparticle solutions to brain-machine interface were predicted a long time ago and are under development today. As shown above, animal data show that nontoxic magnetic particles could be noninvasively directed to specific locations in the brain under realtime imaging guidance. Particles could be placed with high spatial resolution in focal regions for specific clinical indications (addiction, Parkinson's disease). Alternatively, the particles could be globally spread in the brain and selectively addressed for local stimulation and/

**6.4. Spintronic particles**

150 Evolving BCI Therapy - Engaging Brain State Dynamics

of applied RF pulse.

**7. Conclusion**

Irving N. Weinberg1 \*, Lamar O. Mair1 , Sahar Jafari<sup>1</sup> , Jose Algarin<sup>2</sup> , Jose Maria Benlloch Baviera<sup>2</sup> , James Baker-McKee<sup>3</sup> , Bradley English3 , Sagar Chowdhury3 , Pulkit Malik3 , Danica Sun3 , Jamelle Watson-Daniels<sup>3</sup> , Olivia Hale3 , Pavel Y. Stepanov3 , Aleksandar Nacev4 , Ryan Hilaman4 , Said Ijanaten4 , Christian Koudelka<sup>4</sup> , Ricardo Araneda5 , Jens Herberholz<sup>5</sup> , Luz J. Martinez-Miranda<sup>5</sup> , Benjamin Shapiro5 , Pablo S. Villar<sup>5</sup> , Ilya Krivorotov<sup>6</sup> , Sakhrat Khizroev<sup>7</sup> and Stanley Fricke8

