Abstract
The overall goal of this thesis is to explore new wireless approaches for brain stimulation. Wireless and precise stimulation of brain structures are important to study intact brain circuits and augment brain function. However, current technologies of noninvasive brain stimulation usually have low spatial and temporal precision and poor brain penetration, which greatly limit their application. Magnetoelectric nanoparticles (MENPs) provide a minutely invasive brain stimulation approach that does not require surgery, by transforming the energy transmitted through remotely applied magnetic fields into local electric fields. In our applied studies, we demonstrated how magnetoelectric nanoparticles can wirelessly modulate neurons in vitro and in vivo (rodents and non-human primates). We demonstrate this through several different approaches: motor cortex stimulation, mesencephalic locomotor region (cuneiform nucleus) stimulation, and through whole brain stimulation of intranasally administered MENPs. After injecting MENPs into the brain, we activated them with an applied AC magnetic field, which resulted in evoked cortical activities, as revealed by induced motor responses and behavioral changes. We have also found that we can produce different motor responses by modifying the applied magnetic field gradient and orientation, which can allow for a brain-machine interface with a very large number of channels. Thus, MENPs could enable non-invasive and contactless deep brain stimulation without the need for genetic manipulation.