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
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 |
