Brain structure and aggression

- hippocampus
- thalamus
- hypothalamus
- amygdala
key structure involved in aggression is the amygdala (emotional regulation - explaining hot-blooded agression)

rational thinking and decision making
involved in self control impulse regulation and inhibition of aggressive behaviours
reduced activity disrupts its impulse control function

neurotransmitter with widespread inhibitory effects on transmission between neurons in the brain (slows down + dampens neuronal activity)
decreased serotonin reduces self control leading to more impulsive behaviours such a aggression

dopamine is a neurotransmitter that has inhibitory effects in some areas of the brain and excitatory in others
it is involved in regulating motivated behaviour and our experience of reward
serotonin underactivity (hypofuction) stimulates dopamine overactivity (hyperfunction) + both are linked with impulsivity and aggression
serotonin hypofunction is primary cause + dopamine hyperfunction is an additional factor

Raine (1997)
used PET scans to identify brain impairments in murderers pleaded NGRI
found murderers had significantly lower glucose metabolism (less activity) in lateral and medial prefrontal areas than controls
concluded that murderers pleading NGRI have different brain activity than from people who are not violent offenders

23/ 41 murderers had a history of a head injury that was not controlled for
This may have been the factor causing differences in activity between the two groups rather than brain structure/function
leading to inaccurate results lowering internal validity of the study meaning that brain structure may not be the cause of aggression

powerful research evidence for the role of the amygdala in aggression
Pardini (2014) used fMRI scans to find a strong negative correlation between aggression and amygdala volumes
These findings could not be explained by potential confounding variables (race, age, substance abuse, etc.) because they were all controlled for in the study
this means that there is strong support for the influence of the amygdala, therefore providing evidence that brain structure causes aggression

A weakness is that the research into neural influences on aggression is only correlational.
Studies can find links between high levels of aggression and a brain function or structure - but they are unable to find cause and effect, meaning they also cannot find directionality.
For example aggression could lead to alterations in brain structure and function rather than brain structure causing aggression.
This means it is impossible to establish whether a particular structure/function is a cause or effect of aggressive behavioyr, or whether a third variable is onvolved. Therefore, brain structure/function may not be the cause of aggression.

researchers have attempted to overcome this problem (research being only correlational) by using drugs known to increase serotonin activity
for example ppts given paroxetine gave fewer and less intense electric shocks to others (Berman 2009)
This is evidence of a link between serotonin and aggression that goes beyond the usual correlational findings

There are potential practical benefits to understanding neural influences on aggression.
For example, one goal of research is to discover a drug that affects the brains serotonin systen reducing aggressive behaviour with minimal side effects.
A category of serotonin agonist drugs called serenics has been found to have signinficant anti-aggressive effects in animals and humans (Verhoeven + Tuinier 2007)
Showing that research of brain structure and aggression has real life applications to reducing aggression through medication

- limbic system / study
- PFC / raine
- serotonin / correlational research / CA (Berman 2009)
- dopamine / application