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Front Neurosci. 2012 Jul 17;6:90. doi: 10.3389/fnins.2012.00090. eCollection 2012.

Is a 4-bit synaptic weight resolution enough? - constraints on enabling spike-timing dependent plasticity in neuromorphic hardware.

Frontiers in neuroscience

Thomas Pfeil, Tobias C Potjans, Sven Schrader, Wiebke Potjans, Johannes Schemmel, Markus Diesmann, Karlheinz Meier

Affiliations

  1. Kirchhoff Institute for Physics, Ruprecht-Karls-University Heidelberg Heidelberg, Germany.

PMID: 22822388 PMCID: PMC3398398 DOI: 10.3389/fnins.2012.00090

Abstract

Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists.

Keywords: NEST; PyNN; circuit variations; large-scale spiking neural networks; neuromorphic hardware; spike-timing dependent plasticity; synaptic weight resolution; wafer-scale integration

References

  1. PLoS Biol. 2008 Dec 16;6(12):e324 - PubMed
  2. Neural Comput. 2007 Sep;19(9):2281-300 - PubMed
  3. Neuron. 2001 Dec 20;32(6):1149-64 - PubMed
  4. Front Comput Neurosci. 2010 Oct 08;4:129 - PubMed
  5. Eur J Neurosci. 2002 Mar;15(6):984-90 - PubMed
  6. Annu Rev Neurosci. 2001;24:139-66 - PubMed
  7. Network. 2006 Sep;17(3):211-33 - PubMed
  8. Neural Netw. 2007 Jan;20(1):48-61 - PubMed
  9. Nat Rev Neurosci. 2001 Mar;2(3):194-203 - PubMed
  10. J Neurosci. 2005 Feb 23;25(8):2117-31 - PubMed
  11. Nature. 1996 Sep 5;383(6595):76-81 - PubMed
  12. Front Neurosci. 2011 May 31;5:73 - PubMed
  13. Biol Cybern. 2008 Jun;98(6):459-78 - PubMed
  14. Neural Comput. 1998 May 15;10(4):815-9 - PubMed
  15. J Neurosci. 1998 Dec 15;18(24):10464-72 - PubMed
  16. Front Neuroinform. 2009 Jan 27;2:11 - PubMed
  17. Phys Rev Lett. 2001 Jan 8;86(2):364-7 - PubMed
  18. Front Syst Neurosci. 2010 Nov 17;4:151 - PubMed
  19. Front Comput Neurosci. 2011 Feb 14;4:160 - PubMed
  20. Nature. 2007 Sep 6;449(7158):92-5 - PubMed
  21. J Neurosci. 2006 May 24;26(21):5604-15 - PubMed
  22. Neural Netw. 2002 Jun-Jul;15(4-6):507-21 - PubMed
  23. Annu Rev Neurosci. 2005;28:357-76 - PubMed
  24. Neural Comput. 2007 Nov;19(11):2881-912 - PubMed
  25. Neuron. 2006 Apr 6;50(1):115-25 - PubMed
  26. Nature. 1998 Feb 26;391(6670):892-6 - PubMed
  27. PLoS Comput Biol. 2008 Dec;4(12):e1000248 - PubMed
  28. Nature. 2007 Aug 9;448(7154):709-13 - PubMed
  29. J Neurosci. 2012 Jan 4;32(1):194-214 - PubMed
  30. J Comput Neurosci. 2011 Oct;31(2):229-45 - PubMed
  31. Science. 1997 Jan 10;275(5297):213-5 - PubMed
  32. Nature. 2012 Jan 25;482(7383):47-52 - PubMed
  33. IEEE Trans Biomed Circuits Syst. 2008 Sep;2(3):212-22 - PubMed
  34. Proc Natl Acad Sci U S A. 1997 Jan 21;94(2):719-23 - PubMed
  35. Nature. 2002 Dec 19-26;420(6917):788-94 - PubMed
  36. Front Neurosci. 2011 Mar 17;5:26 - PubMed
  37. Science. 2011 Dec 16;334(6062):1569-73 - PubMed
  38. Neural Comput. 2003 Jan;15(1):67-101 - PubMed
  39. J Neurosci. 2003 May 1;23(9):3697-714 - PubMed
  40. Nat Rev Neurosci. 2006 Feb;7(2):153-60 - PubMed
  41. IEEE Trans Biomed Circuits Syst. 2011 Jun;5(3):244-52 - PubMed
  42. Neuron. 2005 Feb 17;45(4):599-611 - PubMed
  43. Neural Comput. 2005 Aug;17(8):1776-801 - PubMed
  44. Adv Exp Med Biol. 2011;696:377-84 - PubMed
  45. Nat Neurosci. 2000 Sep;3(9):919-26 - PubMed
  46. J Neurosci. 2009 Nov 18;29(46):14596-606 - PubMed
  47. J Neurosci. 2000 Dec 1;20(23):8812-21 - PubMed
  48. Biol Cybern. 2011 May;104(4-5):263-96 - PubMed
  49. Neuroscience. 1983 Apr;8(4):791-7 - PubMed
  50. J Comput Neurosci. 2000 May-Jun;8(3):183-208 - PubMed
  51. Chemphyschem. 2002 Mar 12;3(3):276-84 - PubMed
  52. Neural Comput. 2007 Jun;19(6):1437-67 - PubMed
  53. J Comput Neurosci. 2007 Dec;23(3):349-98 - PubMed
  54. PLoS Comput Biol. 2009 Aug;5(8):e1000456 - PubMed

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