Comparison of spontaneous and event related measures in the electroencephalogram

Abstract

Some common descriptors of spontaneous EEG include the common spectral measures (including alpha and beta bands) and the less common measures of statistical moment analysis (such as activity, mobility and complexity). Of these measures, the complexity quantifies the apparent “excessive detail” of the EEG trace. Typically, around 20 seconds of EEG are required to compute these measures.A similar measure can be made in the averaged event related potential (ERP) domain, the “string-length” obtained when the normalized ERP trace is stretched out into a straight line. Several researchers have correlated this parameter with IQ measures in children and adults. Approximately 200 responses (100 seconds) of recorded data are required to form the averaged ERP and compute the string length. The present study examines the relationship between EEG activity, mobility & complexity and ERP string length. This paper describes a pilot study comparing results from moment analysis of EEG with string length. The preliminary results from two individuals indicate that complexity is strongly related to string length. This suggests that a simpler process for obtaining the measures is possible without requiring any stimulus.KeywordsERPEEGstring length