Steven Crane Compiled Section Handouts. Human Behavioral Biology 2012

Neurochemistry of aggression (seconds before the aggressive behavior)

What is the driving force giving your frontal cortex the power to do the harder but right thing?

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  Dopamine
  

Serotonin time

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  What are low levels of serotonin associated with?
  
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    Impulsive behavior. Impulsive aggression.
    
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  How does serotonin synthesis inform our understanding of its role in aggression?
  
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    Serotonin is made from tryptophan. The enzyme that does this conversion is TH.
    
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    When serotonin acts in a synapse, it is then either reuptaken or degraded by MAOb, an enzyme.
    
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    So these actually contradict the "serotonin = impulsive aggression" story. How so?
    
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      Poor MAOb variant means more serotonin will act in the synapse. But people with this variant have
      

more antisocial behavior.

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  And if TH works better you should have more serotonin. But people with better TH tend to have more impulsive violence.
  
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  So it's complicated, m'kay?
  
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  Where else do MAOb variants come in?
  
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    The New Zealand kids study.
    
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    The "good" version makes you less vulnerable to developing antisocial behavior.
    
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    The "bad" version (less effective at degrading serotonin, leaving more in the synapse) predicts more antisocial behavior. With more aggressive childhoods, more antisocial behavior. Need childhood abuse to make it happen. It's a vulnerability. Gene-environment interaction.
    

What effect does alcohol have on aggression?

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  Same story that comes up over and over: it exacerbates pre-existing tendencies. Makes unaggressive individuals less aggressive. Makes aggressive individuals more aggressive.
  
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  Also see this play out with cultures newly introduced to alcohol. They adopt the drunken behavior of the drunken role models of their colonial occupiers.
  
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  What are the two profiles of alcoholism?
  
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    Profile 1: Increases risk of antisocial behavior. Drinking socially. Men.
    

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  Reaching age 30 and you're cured.
  

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  Profile 2: no gender difference. Alcoholism most severe in late middle age. Barely functioning alcoholics drinking alone.
  
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  Heritability separates out the two lines.