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Abstract:
The orbitofrontal cortex, with its subcortical connections,
represents a distinct functional subsystem. We propose that hypo-
and hypermetabolism of the orbitofrontal circuit underlie a
distinct behavioral continuum with specific clinical syndromes
(psychopathy and obsessive-compulsive disorder) representing
extreme deviations in circuit activity. To determine if this
continuum encompasses both clinical syndromes and non-clinical
variations in personality, we monitored subjects) electodermal
activity during the presentation of emotionally-evocative stimuli,
administered personality tests and measures sensitive to
orbitofrontal dysfunction to general population subjects and OCD
patients. Our results demonstrated a relationship between
orbitofrontal dysfunction and specific personality traits. The
connectionist network describes how sensitivity to aversive stimuli
can emerge from either prolonged socialization to attend to harmful
stimuli or from traumatic experiences. Input to the network
consists of semantic feature vectors representing neutral and
aversive stimuli, while the teaching signal is either expected or
actual harm. The network is trained via the backpropagation
algorithm to recode the input vector through a waist of hidden
units, whose size determines how rigidly the input is classified as
aversive or neutral. The network must also maintain an optimal
arousal level via a compensatory behavioral strategy. Additional
parameters are the slope of the sigmoid (which influences the
difficulty of matching the targets) and the cost of failing to
identify harmful stimuli.
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