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Abstract:
Abstract: The orbitofrontal cortices play a key role in
processing emotion, including conscious emotional experience
(feeling), but the single-unit correlates of this have not been
investigated in humans. We recorded single-unit activity from two
epileptic patients with chronically implanted depth electrodes
located in the ventral and dorsal medial prefrontal cortex. The
awake subjects viewed emotionally arousing movie clips (mean
duration: 1 minute) that had been shown reliably to elicit feelings
from normal subjects. We recorded electrophysiological activity
from 16 (24) spatially separate sites in addition to autonomic
indices to clips that elicited happiness, fear, anger, disgust, or
sadness, as well as a neutral control. Multiple tetrode contacts
along electrode shafts permitted cluster isolation of >100
neurons per subject. We found statistically significant modulations
of firing rates in a subset of neurons. Notably, sites recorded in
the right hemisphere showed increased firing rates for disgust and
sadness, but not happiness, whereas sites in left hemisphere showed
increased firing rates for happiness, but not sadness. The findings
provide further evidence that left and right frontal cortices
participate in the conscious experience of positive and negative
emotions, respectively. Supported by grants to R.A. from the Sloan
Foundation, the EJLB Foundation, and the Center for Consciousness
Studies.
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