Estimation of nonlinear neural source interactions via sliced bicoherence

2016-09-01
Neural oscillations and their spatiotemporal interactions are of interest for the description of brain mechanisms. This study offers a novel third order spectral coupling measure named "sliced bicoherence". It is the diagonal slice of cross-bicoherence allowing an efficient quantification of the nonlinear interactions between neural sources. Our methodology comprises an indirect estimation method, a parametric confidence level formula and a subtracted version for robustness to volume conduction. The methodology provides an efficient estimation of third-order nonlinear cross relations reducing the complexity to the same order of second-order coherence computation. Unlike other bispectral measures, the suggested measure solely holds terms related to cross relations between channel sources and omits the possible strong autobispectral relations. Feasibility and robustness of the methodology are demonstrated both on simulated and publicly available MEG data. The latter were collected for a motor task and an eyes-open resting state. Analytical confidence level marked the non-significant couplings. Simulations confirmed that the subtracted bicoherence enabled robustness to volume conduction by avoiding the spurious nearby channel couplings. Central regions were shown to be coupled with muscular activity by sliced bicoherence. Couplings for spontaneous data occurred particularly at theta and alpha bands. Volume-conduction related bicoherence values originated especially from the low frequencies below 5 Hz. The suggested nonlinear measure is promising to be a part of the rich collection of the multichannel electrophysiological brain connectivity metrics.
BIOMEDICAL SIGNAL PROCESSING AND CONTROL

Suggestions

On the Most Informative Slice of Bicoherence That Characterizes Resting State Brain Connectivity
Kandemir, Ahmet Levent; Özkurt, Tolga Esat (2018-08-07)
Bicoherence is a useful tool to detect nonlinear interactions within the brain with high computational cost. Latest attempts to reduce this computational cost suggest calculating a particular 'slice' of the bicoherence matrix. In this study, we investigate the information content of the bicoherence matrix in resting state. We use publicly available Human Connectome Project data in our calculations. We show that the most prominent information of the bicoherence matrix is concentrated on the main diagonal, i....
Representation of Cognitive Processes Using the Minimum Spanning Tree of Local Meshes
Firat, Orhan; Ozay, Mete; Onal, Itir; GİLLAM, İLKE; Yarman Vural, Fatoş Tunay (2013-07-07)
A new graphical model called Cognitive Process Graph (CPG) is proposed, for classifying cognitive processes based on neural activation patterns which are acquired via functional Magnetic Resonance Imaging (fMRI) in brain. In the CPG, first local meshes are formed around each voxel. Second, the relationships between a voxel and its neighbors in a local mesh, which are estimated by using a linear regression model, are used to form the edges among the voxels (graph nodes) in the CPG. Then, a minimum spanning t...
Neural networks with piecewise constant argument and impact activation
Yılmaz, Enes; Akhmet, Marat; Department of Scientific Computing (2011)
This dissertation addresses the new models in mathematical neuroscience: artificial neural networks, which have many similarities with the structure of human brain and the functions of cells by electronic circuits. The networks have been investigated due to their extensive applications in classification of patterns, associative memories, image processing, artificial intelligence, signal processing and optimization problems. These applications depend crucially on the dynamical behaviors of the networks. In t...
Parallel implementation of the boundary element method for electromagnetic source imaging of the human brain
Ataseven, Yoldaş; Gençer, Nevzat Güneri; Department of Electrical and Electronics Engineering (2005)
Human brain functions are based on the electrochemical activity and interaction of the neurons constituting the brain. Some brain diseases are characterized by abnormalities of this activity. Detection of the location and orientation of this electrical activity is called electro-magnetic source imaging (EMSI) and is of signi cant importance since it promises to serve as a powerful tool for neuroscience. Boundary Element Method (BEM) is a method applicable for EMSI on realistic head geometries that generates...
IMPULSIVE SICNNS WITH CHAOTIC POSTSYNAPTIC CURRENTS
Fen, Mehmet Onur; Akhmet, Marat (2016-06-01)
In the present study, we investigate the dynamics of shunting inhibitory cellular neural networks (SICNNs) with impulsive effects. We give a mathematical description of the chaos for the multidimensional dynamics of impulsive SICNNs, and prove its existence rigorously by taking advantage of the external inputs. The Li-Yorke definition of chaos is used in our theoretical discussions. In the considered model, the impacts satisfy the cell and shunting principles. This enriches the applications of SICNNs and ma...
Citation Formats
T. E. Özkurt, “Estimation of nonlinear neural source interactions via sliced bicoherence,” BIOMEDICAL SIGNAL PROCESSING AND CONTROL, pp. 43–52, 2016, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/30732.