Activity detection and causal interaction analysis among independent EEG components from memory related tasks

Abstract

Over the past few years there has been an increased interest in studying the underlying neural mechanism of cognitive brain activity related to memory. In this direction, we study the brain activity based on its independent components instead of the EEG signal itself aiming towards identifying and analyzing induced responses being attributed to oscillatory bursts from local or distant neural assemblies, with variable latency and frequency, in an auditory working memory paradigm. The contribution and functional coupling of independent components to evoked and/or induced oscillatory activities is investigated through the concept of the recently introduced partial directed coherence method, which can also reveal the direction of the statistically significant relationships. The results on read data from an oddball experiment are in accordance with previous psychophysiology studies suggesting increased phase locked activity most prominently in the delta/ theta band, while alpha is also apparent in measures of non phase-locked activity. Dynamic synchronization is inferred between the alpha and delta bands, whereas some influence of the theta band is also detected. This study indicates that functional connectivity during cognitive processes may be successfully assessed using spectral power measures applied on independent components, which reflect distinct spatial patterns of activity.

Graph Analysis and Visualization for Brain Function Characterization Using EEG Data

“…This study indicates that functional connectivity during cognitive processes may be successfully assessed using connectivity measures applied on independent components, which reflect distinct spatial patterns of activity. The results suggest increased phase locked activity most prominently in the delta/ theta band, while alpha is also apparent in measures of non phase-locked activity [91]. Figure 6 depicts numbered ICs.…”

“…Such approaches are most commonly used in analysing cognitive brain function. In the case of an auditory working memory paradigm (oddball experiment), induced responses are attributed to oscillatory bursts from local or distant neural assemblies with variable latency and frequency [91]. The functional coupling and role of independent components are investigated through the concept of PDC method.…”

“…Apart from the synchronization itself, directionality is also identified. The bidirectional coupling indicates no single influence between the "cause" and "effect" relationship [91].…”

Fusion of EEG Topograhic Features and fMRI Using Canonical Partial Least Squares

“…HMMs are the simplest DBN models we can build. In [20], we extended the modeling of the topographic sequence using Dynamic Bayesian Networks. The trained networks were used for the binary classification between two tasks with good results and confirmed that the topographic sequence carries valuable information about the underlying brain processes complementary to the time-frequency analysis approach.…”

“…The encoded sequence is used to learn the parameters of the discrete HMM using the Baum-Welch algorithm [19]. We apply this methodology on the wideband average ERP signal for extracting the topography codebook and learning the model parameters [20].…”