Event-Related Changes in the 40 Hz Electroencephalogram in Auditory and Visual Reaction Time Tasks
Abstract
Mean motor response times (MRT) to expected stimuli can differ considerable between subjects even when experimental conditions are stable. It is well known that central rather than peripheral processes are mainly responsible for these differences. However, questions remain open whether and which measures of neuroelectrical brain activity can reveal significant aspects of the underlying sensorimotor processes. A number of studies using event-related brain potentials have yielded only small or insignificant correlations between electrophysiological measures and motor reaction times. To compute 40Hz band event-related spectra (ERS), each response epoch was first band pass filtered from 20-60 Hz. The epochs were then divided into 68 overlappping 24-point (96ms) time windows with a shift interval of 8 ms. After tapering using a Gaussian window function, and zero-padding to 64 points, each window was converted to spectral power using an FFT. Since gamma band power was interrupted by the 50 Hz notch filter used in the recording, the range 35 to 43 Hz was chosen for analysis. Power in this range was integrated for each time point using a Hamming window function . The 40 Hz ERS transform of each epoch thus consisted of 68 power estimates at 8ms intervals. Statistical significance of response differences in the measures was tested by repeated measures analysis of variance (RM-ANOVA), by Bonferroni-corrected t-tests for dependent samples, and by t- tests for independent samples. Threshold of significance was considered to be p<0.01..
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1994
- Accession Number
- ADA379543
Entities
People
- E. Kuchleri
- H. Jokeit
- R. Goertzl
- S. Makeig
Organizations
- Naval Health Research Center