Biologicalš§ ā¢ Raine et al. Study (1997) Flashcards
What was the aim of the study?
Raine wanted to use a brain scanning technology to identify brain imparments to see if there was a difference in brain structure between people charged NGRI - Not Guilty Reason Insanity (murderers) and normal people (non-murderers).
What did Raine hypothesise?
- That dysfunctions would appear in brain regions previously asociated with violence such as:
- amygdala
- prefrontal cortex
- angular gyrus
- hippocampus
- thalamus
- corpus callosum
Where was the study conducted?
At the university of California
How many people were included in the study (+ sub sections of the people).
- 82 total people
- 41 offenders pleading NGRI
- 41 normal non-murderers
- Within each 41 = 39 men & only 2 women
What was the procedure of the study?
- Each participant from both sections were injected with glucose tracer and were then instructed to preform a continuous performance task (CPT) for 32 mins
- After that the PET scan was conducted
- A urine test was also carried out to make sure NGRI were free from any medication before injected with glucose tracer to ensure accurate results
How were the two groups of 41 participants matched?
- They were matched on:
- age
- sex
- ethnicity
- mental abnormalities (schizophrenia)
How does a PET scan work?
- Inside the brain blood takes oxygen to the regions that are active
- A PET scan will showcase these specific regions as having a higher ammount of the radioactive tracer
- A computer can from this information produce a scan of the brain from the radioactive signals colouring the certain regions specifically
- Scan takes 10 slices (images) at 10mm intervals throughout the brain
What are the coloured regions asociated with on a PET scan?
- Active regions are coloured as āhotā in yellow or red
- Less active regions are coloured as ācoldā in blue or green
What does a PET scan stand for?
Positron Emission Tomography
Why were participants made to do the continuous preformance task?
To ensure they all had a similar mental state during the PET scan and to ensure the radioactive tracer spread to the regions of the brain in order to be observed in PET scan
What did the contiunous preformance task get participants to do?
Participants had to wear earphones and press a button each time they heard a beeping tone
How many NRGI suffered from schizophrenia?
6 NGRIs
How did they match up the NRGIs with schizophrenia to a non-murderer?
They aquired 6 non-murderers that also suffered from schizophrenia to make the results between the pair comparable/ have same variables
What were the results for Raineās study?
- NGRIs showed less activity in frontal lobe than non-murderers, especially the prefrontal cortex which is asociated to rational thinking/ self-restraint/ memory
- NGRIs showed less activity in pareital lobe which is asociated with abstract thinking (justice/ morality) and more activity in the occipital lobe (vision)
- Imbalance of activity between left & right hemispheres, showing possible deficits in corpus callosum therfore lack of communication between hemispheres - lack of optimum levels of cognition
- Unusual influxes of activity throughout limbic system e.g amygdala/ hippocampus - region of the brain asociated with primative human aggresion
What was the conlcusion for Raineās study?
- Deficits in the prefrontal cortex may lead someone to be more impulsive or emotional
- Deficits in the limbic system may lead a person to be much more aggressive due to difficulty learning from previous mistakes or understanding emotions
- Deficits in the corpus callosum make it harder for brain hemispheres to communicate therefore making it harder for person to think about long-term consequences or decisions in general
