Probing the Brain Using Long-Term Implantable e-Skin Magnetic Resonance Imaging Sensors (Akronym E-Brain)
Thanks to its unique specificity and the absence of ionizing radiation, magnetic resonance imaging (MRI) is one of the prime modalities to assess brain function and metabolism. However, the spatial and temporal resolution of MRI is still limited compared to optical or electrophysiological methods. Even at very high magnetic fields up to 10 Tesla or more, it is highly challenging to acquire signals not only reflecting gross activation or metabolic changes of larger cortical areas but to probe functional cortical subunits such as layers or columns within the cerebral cortex. The two main reasons for this limitation are the low intrinsic sensitivity of MR, and the spatially unspecific coupling between neuronal excitation, local blood regulation, and energy metabolism. Therefore, the major objective of the proposed E-Brain project is to overcome these fundamental limitations of conventional MRI by applying an innovative MR detection concept that combines a highly sensitive integrated circuit-based readout with fully biocompatible, long-term implantable microcoil arrays. These ultra-thin coil arrays with a thickness of only a few micrometers, which produce virtually no tissue damage during implantation, can pick up and amplify the MR signal with unprecedented sensitivity and local specificity. Furthermore, the proposed microcoil implants will cover an extended cortical region of several square millimeters, allowing for simultaneous investigations on larger functional units with the high sensitivity of microcoils. By applying this radically new technological MR platform that will emerge from the E-Brain project, we expect to gain much more detailed information on local cerebral blood dynamics, neuronal and glial energy metabolism, and their relation to neuronal activation than it is possible today.