neural and hormonal explanations Flashcards
what is the limbic system?
a central part of the brain involved in processing emotional responses
how does the limbic system contribute to agression?
the cortex works to mediate the level of aggression transmitted in the area by moderating testosterone levels in response to environmental triggers
what happens if the amygdala malfunctions?
(either due to a tumor, damage or atypical development)
levels of testosterone can be raised making aggressive behaviour more likely
research on the limbic system
-Raine et al 1997 - PET scans of 41 murderers and 41 controls,found they had abnormalities in the limbic system
-Sumer et al 2007 - 14y/o girl with a tumor in the limbic system causing aggression, when treated she had normal levels
-Siegel & Victoroff 2009 - neurobiological and behavioral explanations of aggression, found both seemed to be controlled by limbic system
briefly evaluate the limbic system in explaining aggression
-the role of the limbic system isn’t clear cut as its made up of many components so its unclear what parts are involved
-research linking brain abnormalities to violence only shows a vulnerability; some people have a damaged limbic system but don’t display aggressive behaviour
what drug brought on the idea that serotonin had a role in aggression?
Prozac (and various others) had the side effect of lowering serotonin levels which increased aggression
how is serotonin implicated in agression?
its believed that activation in the brains limbic region isn’t controlled as much by the frontal cortex in individuals with low serotonin, meaning they have less control over their emotional responses, which can lead to aggression
research on the role of serotonin
-Cherek et al 1996 - when men take drugs increasing their serotonin, they display lower levels of aggression
-Crockett et al 2009 - serotonin lowered thru diet vs hightened by SSRI’s, diet displayed more retaliatory aggression in game playing, SSRI’s had hightened compassion
-Huber et al 1997 - crayfish aggression with artificially elevated serotonin, while in humans low serotonin elevates aggression
briefly evaluate the role of serotonin in aggression
-Crockett study can explain why some people get aggressive when they haven’t eaten
-much research is on animals, extrapolation issues
-using biochemistry to explain behaviour is deterministic, and in this instance has implications with the legal system
what is aromatase?
an enzyme that metabolises testosterone in the brain, found in the limbic region
what happens if there are reduced levels of aromatase in a person?
testosterone wont have enough enzyme to activate, meaning the response to emotional situations experienced by the amygdala wont prompt a reaction in the testosterone, reducing aggression
what happens if in individual has high levels of testosterone in the orbito-frontal cortex?
activity in the orbito-frontal cortex is reduced, meaning an emotional situation could prompt a hightened emotionally aggressive response
how does testosterone interact with serotonin?
it can reduce serotonergic energy, which can increase aggressive behaviour
research on the role of testosterone
-Connor & Levine 1969 - rats castrated when young had low agression even w/ testosterone injections, whereas castrated as adults got aggressive with injections
-Higley et al 1996 - other factors involved eg social norms
-Ellis et al 2009 - link between crime and testosterone levels
briefly evaluate the role of testosterone
-much research is on animals, extrapolation issues
-problematic to generalise animal findings because of differences in brain physiology
-predictive validity is poor
-testosterone can be measured using saliva samples and cerebro-spinal fluid but hormonal fluctuations occur throughout the day
-testosterone levels may be a product of aggression, not a cause
