Saturday, September 4, 2010

The New Executive Brain V? Emotional brain, basal ganglia etc

Davidson et al. Left hemisphere lesions produce negative affect especially if they are closer to the frontal pole.  Right hemisphere lesions produce euphoria.  Left hemisphere activates to happy film, financial gain, right hemisphere to sad film and financial losses.  In the Ultimate Game, the right hemisphere activated to unfair offers.  Suppression of memories occurs via right or bilateral DLPFC affecting the right hippocampus.Meditation, deactivates left frontal.  Vicarious pain (watching others suffer) activates right frontal.  (Naomi Eisenberger,et al. Science 2003, study of social exclusion). 

Frontal lobes modify attenuate the amygdala (the "pre" prefrontal lobe actor); this done through orbitofrontal cortex.  The amygdala also show evidence of valence mirroring that of evolutionarily later frontal lobe, ie left positive valence, right negative.  Suppressing negative emotions is left DLPFC on left amygdala, fear engendering stimuli affect right amygdala, and lesion of right amygdala reduces the ability to experience fear.  Anxiety may be associated with a large or hyperactive right amygdala.  Emotionally charged crimes may be related to large right amygdala.  Removal of right amygdala may attenuate ability to appreciate emotion of fear in others' faces. 

In gambling experiment, both prefrontal and amygdalaoid lesions interfered with decision making, but only amygdaloid lesion was associated with a change in skin response.  Distant threats in a virtual reality environment were mediated by DFPFC, but immediate threats were mediated by amygdala. 

Author argues novelty/familiarization dichotomy can tie up loose ends of verbal/nonverbal debate. 

Parkinson patients avoid choices leading to bad outcomes (risk aversion) more than selecting ones leading to a good outcome.  (Frank et al., Science 2004). 

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