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Mon, 05 Aug 2013 13:19:17 +0200Mon, 05 Aug 2013 13:19:17 +0200Transfer entropy - a model-free measure of effective connectivity for the neurosciences
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/29499
Understanding causal relationships, or effective connectivity, between parts of the brain is of utmost importance because a large part of the brain’s activity is thought to be internally generated and, hence, quantifying stimulus response relationships alone does not fully describe brain dynamics. Past efforts to determine effective connectivity mostly relied on model based approaches such as Granger causality or dynamic causal modeling. Transfer entropy (TE) is an alternative measure of effective connectivity based on information theory. TE does not require a model of the interaction and is inherently non-linear. We investigated the applicability of TE as a metric in a test for effective connectivity to electrophysiological data based on simulations and magnetoencephalography (MEG) recordings in a simple motor task. In particular, we demonstrate that TE improved the detectability of effective connectivity for non-linear interactions, and for sensor level MEG signals where linear methods are hampered by signal-cross-talk due to volume conduction.Raúl Vicente; Michael Wibral; Michael Lindner; Gordon Pipaarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/29499Wed, 08 May 2013 13:19:17 +0200Goodness-of-fit tests for neural population models: the multivariate time-rescaling theorem
http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/7860
Poster Presentation from Nineteenth Annual Computational Neuroscience Meeting: CNS*2010 San Antonio, TX, USA. 24-30 July 2010 Statistical models of neural activity are at the core of the field of modern computational neuroscience. The activity of single neurons has been modeled to successfully explain dependencies of neural dynamics to its own spiking history, to external stimuli or other covariates [1]. Recently, there has been a growing interest in modeling spiking activity of a population of simultaneously recorded neurons to study the effects of correlations and functional connectivity on neural information processing (existing models include generalized linear models [2,3] or maximum-entropy approaches [4]). For point-process-based models of single neurons, the time-rescaling theorem has proven to be a useful toolbox to assess goodness-of-fit. In its univariate form, the time-rescaling theorem states that if the conditional intensity function of a point process is known, then its inter-spike intervals can be transformed or “rescaled” so that they are independent and exponentially distributed [5]. However, the theorem in its original form lacks sensitivity to detect even strong dependencies between neurons. Here, we present how the theorem can be extended to be applied to neural population models and we provide a step-by-step procedure to perform the statistical tests. We then apply both the univariate and multivariate tests to simplified toy models, but also to more complicated many-neuron models and to neuronal populations recorded in V1 of awake monkey during natural scenes stimulation. We demonstrate that important features of the population activity can only be detected using the multivariate extension of the test. ...Felipe Gerhard; Robert Haslinger; Gordon Pipaarticlehttp://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/7860Tue, 10 Aug 2010 11:34:23 +0200