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Abstract:
Abstract: Lesions in ventromedial prefrontal cortex impair
decision making when choices are guided by feeling, due to a
compromised ability to incorporate reward and punishment from prior
experience into the anticipation of future outcomes. To investigate
the neuronal correlates of this mechanism, we recorded single-unit
responses from 16 spatially separate sites in the dorsal and
ventral medial right prefrontal region of a man with 2 chronically
implanted depth electrodes. Neuronal activity, behavioral
performance, and autonomic responses were recorded synchronously
while the subject performed a computerized gambling task. He was
normal in (1) behavior on the task (learning to avoid risky
decisions), and (2) autonomic responses (increased responses in
anticipation of risk). Single-unit activity correlated with
anticipatory autonomic response immediately prior to a decision,
and correlated with both positive (winning) and negative (losing)
feedback (respective uncorrected Spearman correlations: 0.44,
p<0.01; 0.51, p<0.005; 0.58, p<0.0005). Neuronal
activity discriminated between anticipated outcomes that were
positive and those that were negative in the 1-second epoch prior
to decision (Mann-Whitney U test between 33 "bad/risky" choices and
67 "good/safe" choices: U=57, p<0.0001). Supported by grants to
R.A. from the EJLB Foundation, Sloan Foundation, and Center for
Consciousness Studies.
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