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Kwabena Boahen: Neurogrid--Emulating a million neurons in the cortex

Today, I had a tremendous good fortune to host Professor Kwabena Boahen from Stanford University for a widely attended colloquium talk at Almaden. Professor Boahen is a brilliant scientist and bioengineer who seeks to emulate the brain in hardware. Professor Boahen is a protégé of Professor Carver Mead from CalTech.

My favorite papers amongst his many wonderful articles are Neuronal Ion-Channel Dynamics in Silicon and the now classic Point-to-Point Connectivity Between Neuromorphic Chips using Address-Events. 


The digital technique used to simulate neural activity has not changed since Hodgkin and Huxley pioneered ion-channel modeling in the 1950s. Since then, progress has come incrementally, from computer performance doubling every eighteen months (Moore’s Law), plateauing in recent years, and putting real-time cortex-scale simulations outside the realm of the fastest supercomputers for the foreseeable future. With recent advances in neural recording and imaging techniques, our ability to characterize the brain's structure and function truly trumps our ability to simulate its behavior. Fortuitously, the analog technique developed by neuromorphic engineers over the past two decades has now matured, with the recently developed ability to program various types of ion-channels as well as arbitrary patterns of synaptic connections.

Exploiting the analog technique, Neurogrid will help neuroscientists vet various hypotheses by performing simulations large enough to include interactions between multiple cortical areas yet detailed enough to account for what is known about brain function and neuronal structure. While neuronal-level mechanisms have been linked to network-level functions through computational modeling (e.g., generation of brain rhythms), scaling these models up to the area- and system-levels (where cognition emerges) has proved difficult. In the visual system alone, there are three dozen cortical areas, each with its own representation of the visual scene. It is not understood how conflicting information in these areas is reconciled.

When it is completed this year, Neurogrid will emulate a million neurons in the cortex (i.e., simulate in real-time)—rivaling the performance of 20–200 IBM Blue Gene racks on this particular task—at under a thousandth the cost.


Professor 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 who is using silicon integrated circuits to emulate the way neurons compute, 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, a specialized hardware platform that will enable the cortex’s inner workings to be simulated in detail—something outside the realm of even the fastest supercomputers. Professor Boahen’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 sixty publications to his name, 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. The professor is an avid cyclist.


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