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Abstract:
We investigated changes in the power spectra of the EEG on
trials with correct and incorrect responses in a Stroop-type
paradigm. These changes were compared to the Error-related
Negativity (ERN) component of the event-related potential (ERP)
produced during erroneous responses. On trials with overt errors,
an increase in spectral power in the theta and delta bands, but not
in the alpha band, was observed over frontal midline electrodes in
a time window surrounding the response. The increase in frontal
midline theta activity and changes in the delta band, in terms of
spatiotemporal properties (i.e., the time window and the electrodes
showing maximal effects), appear to be related to the ERN and the
following positive slow wave (PE). ERN has been proposed to
originate from medial frontal areas, in particular, the anterior
cingulate cortex (Gehring et al., 1993). It has also been suggested
that frontal midline theta activity, related to cognitive effort,
is linked to the engagement of the ACC (Gevins et al., 1996). In
line with these proposals, the observed spectral changes suggest
both a common anatomical origin for the ERN and frontal midline
theta, and enhancement of cognitive workload during error
processing. We discuss the functional and anatomical significance
of these observations in the context of other findings with ACC
lesioned patients, and current theories of ACC function.
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