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POSTER PRESENTATION Open Access Towards massively-parallel analytic capabilities for multielectrode recordings Daniel Gardner 1* , Jason Banfelder 1,2 , Ajit B Jagdale 1 , Jonathan D Victor 1,3 From Twentieth Annual Computational Neuroscience Meeting: CNS*2011 Stockholm, Sweden. 23-28 July 2011 Multielectrode recordings now reliably deliver simulta- neous signals from a hundred or more neurons or net- works. However, many analytic techniques are presently computationally limited to smaller numbers of signals, severely hampering our ability to relate these neural sig- nals to brain functions including sensation, perception, decision, and action. To address this imbalance, the Laboratory of Neuroinformatics has begun developing a new open source Neurophysiology Extended Analysis Tool [NEAT]. NEAT leverages existing code bases and new massively-parallel computational technology to enable any multielectrode lab to perform high-throughput informative analyses. The goal is to enable neurophy- siologists using arrays in cortex and elsewhere to per- form analyses online, in real time, that now can be done only offline, and to make possible analyses offline that are now impractical for the number of neurons routinely available to new recording methods. The method is to extend our neuroanalysis.org information- theoretic and other spike train analytics to new gra- phics-processor-derived computational engines [GPUs] supplied on inexpensive drop-in cards. We have begun by evaluating computational bottle- necks in analytic routines, many information-theoretic, developed for our existing Spike Train Analysis Toolkit [STAToolkit]. The STAToolkit is in wide use, having been distributed via neuroanalysis.org to over 1,700 sites [1]. Central to this effort is appreciation of the specific capabilities and restrictions of GPU-parallel platforms. Our experience, that of others in our project who have used GPUs for other areas of biomedicine, and reports from the EEGLab community, all confirm that generic or library-based solutions show only modest perfor- mance gains. We project a greater than order of magni- tude speedup that will allow many offline analyses to be performed in real time during experiments, and now- impractical questions to be explored offline in reason- able compute times. For example, pairwise analyses now possible on 10 or fewer neurons may be extendible to 50 or more. We focus on information-theoretic mea- sures and standard pair-wise correlations, JPSTHs, spec- tra, coherences, and new and significant analyses that present significant loads for multineuron recordings. To aid communities planning similar GPU-enabled analyses, we note that the complex, structured, and hier- archic GPU architecture requires special optimization strategies: decomposing code into >1,000 simultaneous threads is needed to efficiently use the 448 cores on new GPUs, data should be loaded into on-chip memory once and re-used, avoiding transfers to other memory layers, kernel processes must optimize thread/kernel and thread/block instruction execution in few clock cycles, flow control code should control multi-thread warps, not individual threads. Acknowledgements Earlier phases of this work supported by Human Brain Project/ Neuroinformatics via MH057153 and MH068012 from NIMH, NINDS, NIA, and NSF. Author details 1 Laboratory of Neuroinformatics, Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021, USA. 2 Institute for Computational Biomedicine, Weill Cornell Medical College, New York, NY 10021, USA. 3 Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, NY 10021, USA. Published: 18 July 2011 * Correspondence: [email protected] 1 Laboratory of Neuroinformatics, Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY 10021, USA Full list of author information is available at the end of the article Gardner et al. BMC Neuroscience 2011, 12(Suppl 1):P361 http://www.biomedcentral.com/1471-2202/12/S1/P361 © 2011 Gardner et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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POSTER PRESENTATION Open Access

Towards massively-parallel analytic capabilitiesfor multielectrode recordingsDaniel Gardner1*, Jason Banfelder1,2, Ajit B Jagdale1, Jonathan D Victor1,3

From Twentieth Annual Computational Neuroscience Meeting: CNS*2011Stockholm, Sweden. 23-28 July 2011

Multielectrode recordings now reliably deliver simulta-neous signals from a hundred or more neurons or net-works. However, many analytic techniques are presentlycomputationally limited to smaller numbers of signals,severely hampering our ability to relate these neural sig-nals to brain functions including sensation, perception,decision, and action.To address this imbalance, the Laboratory of

Neuroinformatics has begun developing a new opensource Neurophysiology Extended Analysis Tool[NEAT]. NEAT leverages existing code bases and newmassively-parallel computational technology to enableany multielectrode lab to perform high-throughputinformative analyses. The goal is to enable neurophy-siologists using arrays in cortex and elsewhere to per-form analyses online, in real time, that now can bedone only offline, and to make possible analyses offlinethat are now impractical for the number of neuronsroutinely available to new recording methods. Themethod is to extend our neuroanalysis.org information-theoretic and other spike train analytics to new gra-phics-processor-derived computational engines [GPUs]supplied on inexpensive drop-in cards.We have begun by evaluating computational bottle-

necks in analytic routines, many information-theoretic,developed for our existing Spike Train Analysis Toolkit[STAToolkit]. The STAToolkit is in wide use, havingbeen distributed via neuroanalysis.org to over 1,700 sites[1]. Central to this effort is appreciation of the specificcapabilities and restrictions of GPU-parallel platforms.Our experience, that of others in our project who haveused GPUs for other areas of biomedicine, and reportsfrom the EEGLab community, all confirm that generic

or library-based solutions show only modest perfor-mance gains. We project a greater than order of magni-tude speedup that will allow many offline analyses to beperformed in real time during experiments, and now-impractical questions to be explored offline in reason-able compute times. For example, pairwise analyses nowpossible on 10 or fewer neurons may be extendible to50 or more. We focus on information-theoretic mea-sures and standard pair-wise correlations, JPSTHs, spec-tra, coherences, and new and significant analyses thatpresent significant loads for multineuron recordings.To aid communities planning similar GPU-enabled

analyses, we note that the complex, structured, and hier-archic GPU architecture requires special optimizationstrategies:• decomposing code into >1,000 simultaneous threads

is needed to efficiently use the 448 cores on new GPUs,• data should be loaded into on-chip memory once

and re-used, avoiding transfers to other memory layers,• kernel processes must optimize thread/kernel and

thread/block instruction execution in few clock cycles,• flow control code should control multi-thread warps,

not individual threads.

AcknowledgementsEarlier phases of this work supported by Human Brain Project/Neuroinformatics via MH057153 and MH068012 from NIMH, NINDS, NIA, andNSF.

Author details1Laboratory of Neuroinformatics, Department of Physiology and Biophysics,Weill Cornell Medical College, New York, NY 10021, USA. 2Institute forComputational Biomedicine, Weill Cornell Medical College, New York, NY10021, USA. 3Department of Neurology and Neuroscience, Weill CornellMedical College, New York, NY 10021, USA.

Published: 18 July 2011

* Correspondence: [email protected] of Neuroinformatics, Department of Physiology and Biophysics,Weill Cornell Medical College, New York, NY 10021, USAFull list of author information is available at the end of the article

Gardner et al. BMC Neuroscience 2011, 12(Suppl 1):P361http://www.biomedcentral.com/1471-2202/12/S1/P361

© 2011 Gardner et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

Page 2: Towards massively-parallel analytic capabilities for multielectrode recordings

Reference1. Goldberg DH, Victor JD, Gardner D: Spike Train Analysis Toolkit: Enabling

wider application of information-theoretic techniques toneurophysiology. Neuroinformatics 2009, 7:165-178, PMC2818590.

doi:10.1186/1471-2202-12-S1-P361Cite this article as: Gardner et al.: Towards massively-parallel analyticcapabilities for multielectrode recordings. BMC Neuroscience 2011 12(Suppl 1):P361.

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