the structure of the brain and aggression Flashcards
what is aggression?
behaviour that is intended to cause injury. in humans this could be psychological as well as physical injury. in animals aggression if often directed at establishing and maintaining dominance or acquiring resources
what is in the limbic system?
the limbic system comprises of:
- thalamus
- hypothalamus
- hippocampus
- amygdala
what is the role of limbic system in aggression?
the amygdala is a key structure involved in aggression which has a central role in how an organism assesses and responds to environmental threats and challenges.
- the reactivity of the amygdala is a key factor of aggressive behaviour.
what study proves the importance of the limbic system?
Coccaro et al (2007) studied people with intermittent explosive disorder, a major feature of such is a tendency to outbursts of extreme reactive aggression
- ppts’ brains were scanned by fMRI while they views image of faces and showed high levels of amygdala activity when viewing faces of anger where a response was not found in non-IED ppts
what role does the the prefrontal cortex play in aggression?
recent research suggests that the amygdala does not operate in isolation but in tandem with the orbitofrontal cortex.
this is a region in the frontal cortex and is a key player in cognitive functions such as rational thinking
- it is also involved in impulse regulation and patients with psychiatric disorders that feature aggression activity in this area is reduced which disrupts the impulse control.
what study proves that prefrontal cortex has a role in aggression?
Raine et al. (1997) used PET scans to study murderers whose crimes included an overwhelming element of reactive aggression.
- they found a greater glucose metabolism in the amygdala but abnormally low metabolism in the prefrontal cortex compared with a group of matched controls.
what is serotonin?
serotonin is a neurotransmitter with widespread inhibitory effects on transmission between neurons in the brain and slows down and dampens neuronal activity
what is the role of serotonin in aggression?
normal levels of serotonin in the OFC are associated with a reasonable degree of behavioural self-control and leading to more impulsive behaviours including aggression
what is a study that proves the role of serotonin in aggression?
Virkkunen et al (1994) compared levels of a serotonin breakdown product in the cerebrospinal fluid of violent impulsive and violent non-impulsive offenders.
- the levels were significantly lower in the impulsive offenders, who also suffered from more sleep irregularities.
what is dopamine?
dopamine is a neurotransmitter that has inhibitory effects in some areas of the brain and excitatory effects in others
- it is involved in regulating motivated behaviour and our experience of reward
what role does dopamine have on aggression?
dopamine’s main influence on aggression comes through its interaction with serotonin
- Seo et al (2008) serotonin underactivity stimulates dopamine overactivity and both are linked with impulsivity and aggression.
what is the support of brain structure and aggression?
powerful research evidence for amygdala in aggression
- Pardini et al (2014) identified 56 males who had been part of study 20 yrs before (at 6-7)
over 20 yrs these men had consistently behaved aggressively including criminal violence.
using fMRI scans, the researchers found a strong negative correlation between levels of aggression and amygdala volumes
what is a weakness of brain structure and aggression?
the research into neural influences is often correlational
- a study would usually find links between high levels of aggression and a brain function or structure using fMRI scans.
there are good ethical reasons for conducting correlational research because experimental research would have to make people aggressive
however one could use animal research
what is the competing argument?
some researchers have attempted to overcome this problem by using drugs known to increase serotonin activity
- e.g. ppts given paroxetine gave fewer and less intense electric shocks to others (berman et al 2009).
how can this be applied?
there are potential practical benefits to understanding neural influences on aggression
- one goal of research is to discover a drug that affects the brain’s serotonin system, reducing aggressive behaviour with minimal side effects
a category of serotonin agonist drugs called serenics has been found to have significant anti-aggressive effects in animals and humans
