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Abstract:
Evidence from animal research suggests that central control
of the skin conductance response (SCR) to salient stimuli arises in
the reticular formation and posterior hypothalamus, while
modulatory influences derive from the amygdala and cortical
structures. Using [O-15] PET methodology, we sought to map the
peripheral autonomic response to these predicted central regions.
Ten healthy female subjects viewed slides selected from the
International Affective Picture System, consisting of either
emotionally neutral or negative visual content (facial mutilation,
morgue pictures). While viewing slides during each of 8, 60 sec PET
scans, subjects either rated the severity of the aversive content
(encoding phase) or determined whether the images had been
previously presented (recognition phase). While encoding negative
images, compared to neutral images, subjects exhibited greater
SCRs, and cerebral blood flow increased in bilateral amygdala,
thalamic/hypothalamic area, midbrain and left lateral prefrontal
cortex. Correlation maps calculated for regional brain activity and
SCR magnitude during the scanning session showed significant
positive correlations in the right amygdala, midbrain and
thalamus/hypothalamus. Activation in amydala and
thalamus/hypothalamus was significantly less during recognition.
These results show neural correlates of emotional responses in
humans, linking subjective, peripheral physiological and central
measures.
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