section_path: Formation/Neurobiological explanation/Prefrontal cortex
section_name: Prefrontal cortex
paragraph_text: Prefrontal cortex
  
  There is ample evidence that the left prefrontal cortex is activated by stimuli that cause positive approach. If attractive stimuli can selectively activate a region of the brain, then logically the converse should hold, that selective activation of that region of the brain should cause a stimulus to be judged more positively. This was demonstrated for moderately attractive visual stimuli and replicated and extended to include negative stimuli.
  
  Two neurobiological models of emotion in the prefrontal cortex made opposing predictions. The valence model predicted that anger, a negative emotion, would activate the right prefrontal cortex. The direction model predicted that anger, an approach emotion, would activate the left prefrontal cortex. The second model was supported.
  
  This still left open the question of whether the opposite of approach in the prefrontal cortex is better described as moving away (direction model), as unmoving but with strength and resistance (movement model), or as unmoving with passive yielding (action tendency model). Support for the action tendency model (passivity related to right prefrontal activity) comes from research on shyness and research on behavioral inhibition. Research that tested the competing hypotheses generated by all four models also supported the action tendency model.