Lesson 1- neural mechanisms in aggression Flashcards
limbic system and aggression
-papez-maclean limbic theory involves amygdala, hypothalamus, hippocampus, implicated in reactive aggression
-also conntects to cingulate gyrus which is responsible for focusing attention on emotionally significant events
-also has connections to prefrontal cortex which is involved in forward planning and anticipation of reward
-limbic system plays a key role in how an organism responds to environmental threats and challenges, believed to be a key factor in whether we respond aggressively or not to an external stimulus
-hypothalamus: regulation of autonomic nervous system, regulates responses to emotional circumstances, damage can result in inappropriate aggressive response to perceived threat
-amygdala: attaching emotional significance to sensory info
-believed to be hierarchal, signals passed from lower systems to higher in prefrontal cortex where feelings are monitored and interpreted, triggers physical response, crucial for regulating social behaviour and aggressive responses, damage would reduce inhibition of amygdala resulting in higher levels of aggression
serotonin and aggression
-normally, inhibits firing of amygdala, has calming influence
-low serotonin means people cant control their impulsive and aggressive behaviour
-regulates prefrontal cortex, lower levels of serotonin affect our response to external stimuli, easily becomes aggressive and cant control responses, cant anticipate risk and therefore impulsively engages in aggressive behaviour
neural mechanisms strengths
-Kluver and Bucy 1939, used rhesus monkeys, removed main areas of limbic system including amygdala, hippocampus and surrounding cortical areas, found monkeys displayed absence of emotional, motor, and vocal reactions normally associated with stimuli/situations elliciting fear and anger, lesioned monkeys also lost social understanding of group hierarchies and would try to fight more dominant and larger members of group
-more recent tech advances allow neuroimaging techniques to investigate relationship, Wong et al 1997, MRI scans of 19 violent male criminals in Broadmoor hospital and compared size of amygdala with 20 normal control subjects, found volume of amygdala was significantly smaller in 19 violent criminals
-Ferrari et al 2003, allowed male rats to fight with another rat at specific time for ten days, 11th day rat wasnt allowed to fight, found rats dopamine levels rasied by 65%, serotonin levels decreased by 35%
-cause and effect and effect not clear in this study
neural mechanisms weaknesses
-uses animals to provide evidence for aggression in humans, physiologically very different, cant extrapolate findings, cannot be sure processes are the same
-lack of population validity, eg Wongs study had small sample, cant really be generalised
-was also gender bias/beta bias, research confined to males, might not explain aggression in females
-Mann et al 1990, administered dexfenfluramine, depletes serotonin in the brain, to 35 healthy adults, researchers used questionnaire to assess hostility and aggression levels, rose following administration amongst males but not females, gender differecnes in neural mechanisms, different physiological factors
