Project Summary There is currently a surging effort to develop the necessary technologies for recording neural activity from the entire volume of the brain in parallel. A whole-brain direct readout of neural signals will be critical to understanding the elusive cross-regional communication grid underlying brain function and dysfunction. The overall goal of this new innovator award is the development and application of a new form of brain imaging us- ing electromagnetic circuits that can be deployed throughout the brain and provide parallel volumetric electro- physiological readouts of neural activity. The project relies on recent advances made by the principal investiga- tor, demonstrating the use of tetherless microelectronic neural interfaces that transduce neurophysiological events wirelessly to detectable magnetic field perturbations, and are monitored by functional magnetic reson- ance imaging (fMRI). By combining the unique three-dimensional capabilities of fMRI to obtain functional rea- douts from the entire volume of the brain, with electromagnetic probes—that are able to directly record electro- physiological neural activity in-situ and transmit its response to the MRI hardware—this project is aiming to transform the way we acquire brain signals. We will use novel nanofabrication methods to pioneer cell-sized wireless probes, while employing existing state-of-the-art MRI-compatible microelectrode arrays in rodents for rigorous validation of the technology and to decouple the electrophysiogical readouts from intrinsic fMRI blood flow signals. The engineering advances that occurred in recent years have propelled the capabilities of both electrical and optical implantable probes for brain recording, achieving nanometer scale spatial resolution, high signal-to-noise ratio and temporal response, and increasingly favorable tissue-device interactions. Implantable electrode array devices provide us with multiplexed recordings of electrical signals from tens or hundreds of neurons with high spatial precision at the cellular level. These devices have been successfully implanted in human patients for the treatment and monitoring of epilepsy and to improve quality of life for tetraplegic pa- tients. The neuroelectronic fMRI probes that will be developed under the umbrella of this award will greatly augment these capabilities. Firstly, by presenting a different approach whereby minimally invasive devices are powered by the MRI scanner itself and do not require bulky on-board power, and secondly, by interacting with the imaging scanner to transmit electrical neural activity to the detection hardware outside of the brain with no requirement for a tethered connection. The sensors will be used to directly detect electrical neural activity in three dimensions, and will help pave the way towards tracing the cross-regional origins of both normal and ab- normal brain physiology.