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Abstract:
Focal electrical fields recorded over the midline prefrontal
cortex have been found to index rapid evaluative decisions, such as
the discrimination of good from bad targets in a video game, or the
recognition of having made an error in a speeded response task. An
important question is whether these apparent evaluative mechanisms
are predictive of changes in behavior. By mapping the electrical
potentials with a dense sensor array, and by filtering out the
large slow waves, we found that the error-related negativity arises
from a midline frontal oscillation that alternates with
oscillations over lateral sensorimotor cortex. Both the midline and
the lateral oscillations have a period of about 200 ms (EEG theta),
and they are present for both correct and error responses. When an
error is made, the midline error oscillation is recruited strongly,
it is synchronized with the response, and it becomes correlated
with the motor oscillations. Electrical source analyses localize
the midline error oscillation to centromedial frontal cortex
(anterior cingulate gyrus and supplementary motor area) and the
lateral oscillation to both motor and somatosensory cortices. These
findings suggest a close link between the evaluative functions of
medial frontal cortex and the dynamic control of action.
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