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Free keywords:
Amygdala; Unilateral temporal lobectomy; Emotion; Emotional visual stimuli; Backward masking; Awareness; EDA
Abstract:
To investigate the function of the amygdala in human emotional
cognition, we investigated the electrodermal activity (EDA) in
response to masked (unseen) visual stimuli. Six epileptic sub-
jects were investigated after unilateral temporal lobectomy.
Emotionally valenced photographic slides (10 negative, 10 neu-
tral) from the International Affective Picture System were pre-
sented to their unilateral visual fields under either subliminal or
supraliminal conditions. An interaction between hemispheres
and emotional valences was found only under the subliminal
conditions; greater EDA responses to negative stimuli com-
pared with neutral ones were observed when stimuli were
presented to the intact hemispheres. The findings suggest that
nonconscious emotional processing is reflected in EDA in a
different manner from conscious emotional processing. Medial
temporal structures, including the amygdala, thus appear to
play a critical role in the neural substrates for this automatic
processing.
