Transcript Neural and Hormonal Mechanisms in Aggression

Neural and Hormonal
Mechanisms in Aggression
Neurotransmitters
• Chemicals that enable impulses in the
brain.
• Transmit form one area of the brain to the
other.
• Low levels of SEROTONIN and high levels
of DOPAMINE have been linked to
aggression in animals (and humans!)
SEROTONIN
• Thought to reduce aggression by inhibiting
responses to emotional stimuli.
• Low levels of serotonin in the brain is associated
with increased susceptibility to impulsive
behaviour.
• Some drugs alter serotonin levels and increase
aggressive behaviour.
• Mann et al. (1990) gave drug dexfenfluramine to
35 healthy subjects – increased hostility )in
males)
DOPAMINE
• Some link between high levels of
dopamine and aggression.
• Use of amphetamines linked to increases
in aggressive behaviour (Lavine, 1997)
• Antipsychotics reduce dopamine activity
have reduced aggressive behaviour in
violent delinquents (Buitelaar, 2003)
HORMONAL MECHANISMS
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•
Testosterone
The male sex hormone
Influence aggression from young
adulthood.
a) Research Studies – Dabbs et al (1987)
Criminals – Higher testosterone levels
has a history of primarily violent crimes
HORMONAL MECHANISMS testosterone
b) The challenge hypothesis – Wingfield et
al (1990) in monogamous species
testosterone levels should only rise above
the baseline breeding level in response to
SOCIAL CHALLENGES (male-male
aggression)
A testosterone surge is expected with an
increase in aggression
HORMONAL MECHANISMS
• Cortisol
• Has a mediating effect on aggressionrelated hormones because it increases
anxiety and social withdrawal. (Dabbs et
al., 1991)
• High levels of cortisol can inhibit
testosterone levels.
STUDIES
• Meta-analysis studies, showing the link
between aggression and
• A) Neurotransmitters
• B) Testosterone
Reductionism
• What is biological reductionism?
• GENDER BIAS: Is aggression a male
phenomenon?