Cell assemblies, defined as groups of neurons exhibiting precise spike coordination, were proposed as a model of network processing in the cortex. Fortunately, in recent years considerable progress has been made in multi-electrode recordings, which enable recording massively parallel spike trains of hundred(s) of neurons simultaneously. However, due to the challenges inherent in multivariate approaches, most studies in favor of cortical cell assemblies still resorted to analyzing pairwise interactions. However, to recover the underlying correlation structures, higher-order correlations need to be identified directly. Inspired by the Accretion method proposed by Gerstein et al. (1978) we propose a new assembly detection method based on frequent item set mining (FIM). In contrast to Accretion, FIM searches effectively and without redundancy for individual spike patterns that exceed a given support threshold. We study different search methods, with which the space of potential cell assemblies may be explored, as well as different test statistics and subset conditions with which candidate assemblies may be assessed and filtered. It turns out that a core challenge of cell assembly detection is the problem of multiple testing, which causes a large number of false discoveries. Unfortunately, criteria that address individual candidate assemblies and try to assess them with statistical tests and/or subset conditions do not help much to tackle this problem. The core idea of our new method is that in order to cope with the multiple testing problem one has to shift the focus of statistical testing from specific assemblies (consisting of a specific set of neurons) to spike patterns of a certain size (i.e., with a certain number of neurons). This significantly reduces the number of necessary tests, thus alleviating the multiple testing problem. We demonstrate that our method is able to reliably suppress false discoveries, while it is still very sensitive in discovering synchronous activity. Since we exploit high-speed computational techniques from FIM for the tests, our method is also computationally efficient.
Keywords: massively parallel spike trains, cell assembly, synchronous spike patterns, higher-order correlation, frequent item set mining, surrogate data, multi-variate significance testing
Citation: Picado-Muiño D, Borgelt C, Berger D, Gerstein G and Grün S (2013) Finding neural assemblies with frequent item set mining. Front. Neuroinform. 7:9. doi: 10.3389/fninf.2013.00009
Received: 18 February 2013; Paper pending published: 08 April 2013;
Accepted: 13 May 2013; Published online: 31 May 2013.
Edited by:Daniel Gardner, Weill Cornell Medical College, USA
Reviewed by:Stephen C. Strother, University of Toronto, Canada
Copyright © 2013 Picado-Muiño, Borgelt, Berger, Gerstein and Grün. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.
*Correspondence: David Picado-Muiño, European Centre for Soft Computing, Calle Gonzalo Gutiérrez Quirós s/n, 33600 Mieres, Asturias, Spain e-mail: firstname.lastname@example.org