Browsing by Author "Chung, WP"

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An approach to quantifying the multi-channel EEG spatial-temporal feature
(2000)
Lo, PC
;
Chung, WP
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Investigation of spatial characteristics in the multi-channel EEG (electroencephalogram) has been of great importance to the fundamental and clinical medicine. Conventional methods are mostly based on the coherence and correlation analysis in time and frequency domain. The authors present the method of quantifying the global waveform complexity in EEG by analyzing the high-dimensional state-space trajectory constructed from the multi-channel EEG. The resulting average complexity index (<()over bar>) is well distinct between the background (4.0 similar to 4.5) and event (3.0 similar to 3.5 for the focal-sharp-wave transient) in the 5-channel case study. In addition, the running <()over bar> measurement for different electrode arrays, for a fixed number of state-space dimension (n = 5), reveals the EEG spatial characteristic. An array composed of nearby channels with similar EEG activities tends to have a small <()over bar>. On the other hand, the computed <()over bar> increases as the array consists of electrode sites with spatially incorrelated EEG activities. Thus the method is capable of quantifying the spatial-temporal feature of the multi-channel EEG.
An efficient method for quantifying the multichannel EEG spatial-temporal complexity
(2001-03-01)
Lo, PC
;
Chung, WP
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The complexity index (delta) quantifies the intrinsic dimensionality of the global complexity of a point set, and was shown to be able to characterize electroencephalogram spatial-temporal features. The complexity index is conceptually comprehensible and easily implemented, yet, it is time consuming. In this paper, we present an efficient computational method based on the projection of the high-dimensional state-space points onto a one-dimensional axis. The computational time decreases by at least 50%, without affecting the measure accuracy.