Brain-implantable biomimetic electronics as the next era in neural prosthetics

An interdisciplinary multilaboratory effort to develop an implantable neura l prosthetic that can coexist and bidirectionally communicate with living b rain tissue is described. Although the final achievement of such a goal is many years in the future, it is proposed that the path to an implantable pr osthetic is now definable, allowing the problem to be solved in a rational, incremental manner Outlined in this report is our collective progress in d eveloping the underlying science and technology that will enable the functi ons of specific brain damaged regions to be replaced by multichip modules c onsisting of novel hybrid analog/digital microchips. The component microchi ps are "neurocomputational" incorporating experimentally based mathematical models of the nonlinear dynamic and adaptive properties of biological neur ons and neural networks. The hardware developed to date, although limited i n capacity, can perform computations supporting cognitive functions such as pattern recognition, but more generally will support any brain function fo r which there is sufficient experimental information. To allow the "neuroco mputational " multichip module to communicate with existing brain tissue, a nother novel microcircuitry element has been developed-silicon-based multie lectrode arrays that are "neuromorphic, i.e., designed to conform to the re gion-specific cytoarchitecture of the brain, When the "neurocomputational " and "neuromorphic" components are fully integrated, our vision is that the resulting prosthetic, after intracranial implantation, will receive electri cal impulses from targeted subregions of the brain, process the information using the hardware model of that brain region, and communicate back to the functioning brain. The proposed prosthetic microchips also have been desig ned with parameters that can be optimized after implantation, allowing each prosthetic to adapt to a particular user/patient.