Connectionists: New Paper: Bayesian Computation Emerges in Generic Cortical Microcircuits through Spike-Timing-Dependent Plasticity

[Bernhard Nessler]

Dear colleagues,

I would like to draw your attention to a new paper we recently published in
PLoS Computational Biology. The paper is available at:

http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1003037


TITLE:
Bayesian Computation Emerges in Generic Cortical Microcircuits through Spike-Timing-Dependent Plasticity

AUTHORS:
Bernhard Nessler, Michael Pfeiffer, Lars Buesing, Wolfgang Maass

ABSTRACT:
The principles by which networks of neurons compute, and how spike-timing dependent plasticity (STDP) of synaptic weights generates and maintains their computational function, are unknown. Preceding work has shown that soft winner-take-all (WTA) circuits, where pyramidal neurons inhibit each other via interneurons, are a common motif of cortical microcircuits. We show through theoretical analysis and computer simulations that Bayesian computation is induced in these network motifs through STDP in combination with activity-dependent changes in the excitability of neurons. The fundamental components of this emergent Bayesian computation are priors that result from adaptation of neuronal excitability and implicit generative models for hidden causes that are created in the synaptic weights through STDP. In fact, a surprising result is that STDP is able to approximate a powerful principle for fitting such implicit generative models to high-dimensional spike inputs: Expectation Maximization. Our results suggest that the experimentally observed spontaneous activity and trial-to-trial variability of cortical neurons are essential features of their information processing capability, since their functional role is to represent probability distributions rather than static neural codes. Furthermore it suggests networks of Bayesian computation modules as a new model for distributed information processing in the cortex.


Any comments or opinions are very welcome!

Best regards
Bernhard Nessler


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DI Bernhard Nessler
Institute for Theoretical Computer Science
Graz University of Technology
Inffeldgasse 16b, A-8010 Graz, Austria
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nessler at igi.tugraz.at
http://www.igi.tugraz.at/
Tel.: ++43 316 873-5823
Fax:  ++43 316 873-5805
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