ISSN 1556-6757


SJI 


 

 

 

 

 
 
 

Volume 1, Issue 1, 2009

 
 

Localizing Sources of the P300 using ICA, SSLOFO, and Latency Mapping
Paul H. Schimpf and Hesheng Liu
 

Abstract
This article demonstrates an approach to inverting the electroencephalogram (EEG) that
provides both spatial and temporal information on the neural generators of event related
potentials (ERP). The ERP is first extracted from background EEG activity using
Independent Component Analysis (ICA). The locations of source activity are then
estimated using Standardized Shrinking LORETA-FOCUSS (SSLOFO). A latency map is
then produced based on the peaks of the estimated source waveforms. This technique is
shown to be capable of localizing the P300 ERP to regions that are comparable to those
obtained in functional neuroimaging studies, while retaining the temporal resolution
advantages of the EEG. Full Article


 


An Analysis on the Role of Water Content and State on Effective Permittivity Using Mixing Formulas   Mark J Schroeder, Anupama Sadasiva, Robert M Nelson

Abstract
Two and three-phase Maxwell Garnett mixing formulas are used in conjunction with uncertainty analysis to investigate the extent to which water content and state (free or bound) influence the effective permittivity of biological materials. The results show that a given percent variation in water content can potentially translate into an even larger variation in effective permittivity. Coupled with bound water effects, the variations can account for an appreciable amount of permittivity ranges found in literature. Realizing the considerable effects of water, researchers can benefit by tightly controlling or noting the water content and state when measuring or modeling biological tissue. Full Article