Magnetic Stimulation of Dissociated Cortical Neurons on a Planar Mulitelectrode Array

Abstract

We perform experiments to study the magnetic stimulus-induced changes in neural activity in dissociated cortical neurons with different stimulation parameters. The goal of performing these studies is to build on the results from our previous work that suggested magnetic stimulation may lead to improved performance of cochlear implants. A magnetic stimulator is assembled using a micro-scale coil. To detect small changes in activity, we use glass substrate MEAs to measure culture-wide synaptically-mediated response to stimulation, rather than the direct activation of individual neurons. Our initial findings show magnetic stimulation is associated with changes in network-wide firing rates, beyond those expected by spontaneous drift in activity. This suggests that the magnetic stimulation parameters we used were able to evoke neural activity. However, we observe substantial differences in the type of change induced in neural activity in different cultures and with different stimulation parameters, some showing increases in activity and others showing decreases in activity. This may be due to differences in the number and type of neurons (inhibitory or excitatory) activated by stimulation in different experiments, which in turn may be affected by differences in stimulator location and alignment, differences in stimulus pulse waveform and amplitudes, or differences in culture density or cell morphology. We also compare the power consumption and heating of this stimulation technique with that of electrical stimulation. Finally, a need to optimize the experimental setup to allow longer experiments is identified, to reach definite conclusions.