Event-related covariances during a bimanual visuomotor task. I. Methods and analysis of stimulus- and response-locked data.
A new method that measures between-channel, event-related covariances (ERCs) from scalp-recorded brain signals has been developed. The method was applied to recordings of 26 EEG channels from 7 right-handed men performing a bimanual visuomotor judgment task that required fine motor control. Covariance and time-delay measures were derived from pairs of filtered, laplacian-derived, averaged wave forms, which were enhanced by rejection of outlying trials, in intervals spanning event-related potential components. Stimulus- and response-locked ERC patterns were consistent with functional neuroanatomical models of visual stimulus processing and response execution. In early post-stimulus intervals, ERC patterns differed according to the physical properties of the stimulus; in later intervals, the patterns differed according to the subjective interpretation of the stimulus. The response-locked ERC patterns suggested 4 major cortical generators for the voluntary fine motor control required by the task: motor, somesthetic, premotor and/or supplementary motor, and prefrontal. This new method may thus be an advancement toward characterizing, both spatially and temporally, functional cortical networks in the human brain responsible for perception and action.
Gevins
A S
AS
EEG Systems Laboratory, San Francisco, CA 94107.
Bressler
S L
SL
Morgan
N H
NH
Cutillo
B A
BA
White
R M
RM
Greer
D S
DS
Illes
J
J
D000328:Adult; D001921:Brain / Q000502:physiology; D004569:Electroencephalography; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time; D013223:Statistics as Topic; D013850:Thinking / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology