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<p class=MsoNormal><span style='color:#1F497D'>TITLE: Anatomy of a
Cortical Simulator<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>AUTHORS: Rajagopal
Ananthanarayanan and Dharmendra S. Modha, IBM Almaden Research Center<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>CONFERENCE: Supercomputing 2007,
Reno, NV, Nov 10-16<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>ABSTRACT: Insights into
brain's high-level computational principles will lead to novel cognitive
systems, computing architectures, programming paradigms, and numerous practical
applications. An important step towards this end is the study of large networks
of cortical spiking neurons.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>We have built a cortical
simulator, C2, incorporating several algorithmic enhancements to optimize the
simulation scale and time, through: computationally efficient simulation of
neurons in a clock-driven and synapses in an event-driven fashion; memory
efficient representation of simulation state; and communication efficient
message exchanges.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>Using phenomenological,
single-compartment models of spiking neurons and synapses with spike-timing
dependent plasticity, we represented a rat-scale cortical model (55 million
neurons, 442 billion synapses) in 8TB memory of a 32,768-processor BlueGene/L.
With 1 millisecond resolution for neuronal dynamics and 1-20 milliseconds
axonal delays, C2 can simulate 1 second of model time in 9 seconds per Hertz of
average neuronal firing rate.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>In summary, by combining
state-of-the-art hardware with innovative algorithms and software design, we
simultaneously achieved unprecedented time-to-solution on an unprecedented
problem size.<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>LINK TO PDF FILE: http://sc07.supercomp.org/schedule/event_detail.php?evid=11063</span><o:p></o:p></p>
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