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Abstract:
The role of hemispheric asymmetry in emotion has long been a
topic of controversy. While early theories highlighted the
importance of right hemisphere function in emotional processes,
more recent human lesion and electrophysiological studies point
towards differential involvement of left and right frontal cortical
regions in the experience of positive and negative emotion,
respectively. The recent application of functional neuroimaging to
the study of emotion offers new data that may be useful in testing
this latter hypothesis, but conclusions drawn from individual
studies are often compromised by limited statistical power and
suboptimal control conditions. In the present study, we combined
data from over 20 studies of positive (happiness, pleasantness) and
negative (sadness, anger, fear, guilt, disgust, anxiety,
unpleasantness) emotions induced using varied mood induction
techniques (retrieval of emotional memories, film clips, affective
pictures); all included a neutral emotion condition and mood
manipulation check. Peak frontal maxima points from these studies
were superimposed onto the standard Statistical Parametric Mapping
brain surface. The pooled results for positive emotions showed
consistent activation of medial and dorso-medial frontal cortical
regions, particularly in the left hemisphere; for negative
emotions, bilateral activation of ventral, ventro-lateral, and
medial prefrontal cortex was observed. These findings are not
entirely consistent with previous work on hemispheric differences
in emotion. Methodological and theoretical explanations for these
differences are considered.
Supported by the Medical Research Council.
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