Criminal. behaviour - amygdala

• Amygdala


  An almond-shaped structure in the brain
• You have two amygdalae
• Amygdalae


  • Located close to the hippocampus, in the frontal portion of the temporal lobe
• Amygdalae


  Essential to your ability to feel certain emotions and to perceive them in other people
• Emotions perceived by the amygdalae

  Fear and the many changes that it causes in the body
• You are being followed at night by a suspect-looking individual


  Your heart is pounding and your amygdalae are very active
• Damage to the amygdala can result in reduced ability to process emotional stimuli, leading to deficits in social behavior and emotion recognition.
• Intermittent explosive disorder


  Involves repeated, sudden episodes of impulsive, aggressive, violent behaviour or angry verbal outbursts in which you react grossly out of proportion to the situation
• Signs of intermittent explosive disorder


  • Road rage
  • Domestic abuse
  • Throwing or breaking objects
  • Temper tantrums
• Intermittent explosive disorder


  • Causes significant distress
  • Negatively impacts relationships, work and school
  • Can have legal and financial consequences
• Intermittent explosive disorder


  A chronic disorder that can continue for years, although the severity of outbursts may decrease with age
• Treatment for intermittent explosive disorder


  1. Medications

  2. Psychotherapy to help control aggressive impulses
• Aggression


  Linked to the amygdala
• people with IED are more likely to engage in criminal behaviour, in particular violent crime, due to the aggression and impulsivity that is part of the disorder. There is evidence that high levels of amygdala activity may be the cause of this disorder.
• Coccaro (2007)

  Investigated the effects of the amygdala on aggression by studying people with IED, a common symptom of which is reactive aggression. 

  P’s viewed images of faces whilst having an fMRI.

  Ps with IED showed high levels of amygdala activity when they viewed angry faces - demonstrating an association between amygdala activity and the processing of aggressive emotions.
• Matthies et al (2012) investigated the relationship between amygdala size and aggression
• Previous morphometric brain imaging studies have focused on the role of the amygdala in the context of pathologic neuropsychiatric conditions like depression, personality disorders, and dysphoric and aggressive behaviour in epilepsy
• Matthias et al 2012

  Objective. Several lines of evidence suggest an association between the amygdala and the modulation of aggressive behaviour. Previous morphometric brain imaging studies have focused on the role of the amygdala in the context of pathologic neuropsychiatric conditions like depression, personality disorders, and dysphoric and aggressive behaviour in epilepsy. In order to better understand the physiological role of the amygdala in modulating aggressive behaviour we investigated the relationship between amygdala volumes and lifetime aggression in healthy subjects.
• Morphometric brain scans


  Brain scans used to measure brain structure
• Participants


  • 20 healthy volunteers
• Amygdala volume measurement


  1. Manually outlining the boundaries of the structure

  2. Following a well-established and validated protocol
• Psychiatric and psychometric assessment


  Careful assessment to exclude psychiatric disorder and assess lifetime aggressiveness
• Life History of Aggression Assessment (LHA)


  Established and validated psychometric instrument to assess lifetime aggressiveness
• All volunteers scored in the normal range of lifetime aggression
• Volunteers with higher aggression scores

  Displayed a 16–18% reduction of amygdala volumes
• Amygdala volumes


  Negatively correlated with trait aggression
• There was a highly significant negative correlation between amygdala volumes and trait aggression
• Matthias et al 2012

  Conclusion. The extent of volumetric differences in this study is remarkable and suggests that amygdala volumes might be a surrogate marker for the personality property of aggressiveness in healthy human beings.
• Amygdala and fear conditioning

  Fear conditioning is where we learn that aggressive behaviour leads to punishment and other negative outcomes. 

  Dysfunction of the amygdala means we cannot identify threats (angry faces), so we do not link aggression to punishment.
• Gao (2010)

  Longitudinal study where 1,795 ps were tested for fear conditioning at 3.  The measure was physiological arousal (sweating) in response to a painful noise.

  20 years later the researchers found out which participants had been involved in criminal behaviour.

  Those who had committed crimes at 23 had shown no fear conditioning when they were 3. They were ‘fearless’.  

  Suggests a causal relationship between amygdala dysfunction and antisocial/criminal behaviour.
• Feinstein et al (2012) investigated the rare case of a woman named SM who had lesions to both amygdala. This caused her to be unable to experience fear.
• Feinstein et al (2012)

  Highlights

  • Case study of patient SM, a rare human patient with focal bilateral amygdala lesions
  • First investigation of the induction and experience of fear in such a patient
  • SM failed to exhibit fear behaviours, and her fear experience was highly impoverished
  • The human amygdala plays a pivotal role in triggering a state of fear
• Amygdala


  A brain structure that plays a pivotal role in triggering a state of fear
• Clinical observations suggest that humans with amygdala damage have abnormal fear reactions and a reduced experience of fear
• The impressions of abnormal fear reactions and reduced fear experience in humans with amygdala damage have not been systematically investigated
• A new study was conducted in a rare human patient, SM, who has focal bilateral amygdala lesions
• Methods to provoke fear in SM


  1. Exposed her to live snakes and spiders

  2. Took her on a haunted house tour

  3. Showed her emotionally evocative films
• On no occasion did SM exhibit fear, and she never endorsed feeling more than minimal levels of fear
• Across a large battery of self-report questionnaires, 3 months of real-life experience sampling, and a life history replete with traumatic events, SM repeatedly demonstrated an absence of overt fear manifestations and an overall impoverished experience of fear
• Despite her lack of fear, SM can exhibit other basic emotions and experience the respective feelings