Modeling the Brain with Neuromorphic Chips

The digital technique used to simulate neural activity has not changed since Hodgkin and Huxley pioneered ion-channel modeling in the 1940s. Since then, progress has come through integrated circuit miniaturization, which doubles computer complexity every eighteen months (Moore’s Law). This trend has plateaued in recent years, making real-time brain-scale simulations unattainable in the foreseeable future, even for the fastest supercomputers. Fortuitously, with the recently developed ability to emulate (i.e., simulate in real-time) various types of ion-channels, as well as arbitrary patterns of synaptic connections in silicon, the analog technique pursued by neuromorphic engineers over the past two decades has matured to the point where the brain can be modeled. Neurogrid, a specialized hardware platform created at Stanford, now can emulate a million cortical neurons—rivaling the performance of 20 IBM Blue Gene racks on this particular task—using five orders of magnitude less energy. By providing an affordable platform to perform simulations at a scale large enough to include interactions between cortical areas, yet detailed enough to account for what is known about neuronal types, Neurogrid will help neuroscientists vet various hypotheses about how the brain works.

Presenter(s)

Kwabena Boahen joined Stanford’s Bioengineering Department as Associate Professor in December 2005. From 1997 to 2005 he was on the faculty of University of Pennsylvania, Philadelphia PA. He is a bioengineer using silicon integrated circuits to emulate the way neurons compute, and linking the seemingly disparate fields of electronics and computer science with neurobiology and medicine. His interest in neural networks developed soon after he left his native Ghana to pursue undergraduate studies in Electrical and Computer Engineering at Johns Hopkins University, Baltimore, in 1985. He went on to earn a doctorate in Computation and Neural Systems at the California Institute of Technology in 1997. His lab is currently developing Neurogrid, which will enable the cortex’s inner workings to be simulated in detail at an affordable energy cost. Kwabena’s numerous contributions to the field of neuromorphic engineering include a silicon retina that could be used to give the blind sight, and a self-organizing chip that emulates the way the juvenile brain wires itself up. His scholarship is widely recognized, with over seventy publications, including a cover story in the May 2005 issue of Scientific American. He has received several distinguished honors, including a Fellowship from the Packard Foundation in 1999, a CAREER award from the National Science Foundation in 2001, a Young Investigator Award from the Office of Naval Research in 2002, and the National Institute of Health Director’s Pioneer Award in 2006. Kwabena is also an avid cyclist.