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Abstract:
Cortical activation in the motor area, based upon EEG
measures, has been shown to be related to movement processing
demands (Pulvermhller, et al., 1995). We tested whether graded
cortical activation in the motor area can be distinguished due to
differing levels of movement difficulty, stimulus novelty and/or
discrimination requirements. A pointing and a reacting task were
employed. The pointing task was an 8-cm movement task in which
continuous EEG was recorded at motor sites. Laplacian and averaged
ears references were used to examine alpha and 40 Hz. bandwidths.
In each of two conditions, a frequent arrow (80%) or a rare arrow
(20%) was presented briefly to specify movement direction from a
central position. In the narrow condition, the frequent arrow
appeared 20deg. clockwise/counter-clockwise from the rare arrow. In
the wide condition, the frequent arrow appeared 120deg.
clockwise/counter-clockwise from the rare arrow. In both
conditions, the rare arrow specified the same movement direction.
The reacting task replaced the pointing response with a
non-directional lift; all other task characteristics were
identical. EEG was collected one second post stimulus. EEG data
(n=10) indicated a task by condition interaction and a task by
probability interaction which support the hypotheses. It is
concluded that movement and stimulus processing demands are
reflected in motor area activation. Supported by NSF grant
SBR-9709361.
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