Biological Psychology: Brain Structure and Aggression

Limbic System

• Hypothalamus: Regulates hormones, sleep, mood, hunger, thirst, sexual arousal, blood pressure, body temperature, and heart rate.

• Thalamus: Processes sensory information and aids memory, planning, and emotions.

• Hippocampus: Responsible for forming new memories.

• Amygdala: Influences emotions (anxiety, anger, fear), memory, social interpretations, and responses to environmental threats.

  • Coccaro et al (2007) found high amygdala activity in individuals with intermittent explosive disorder when viewing angry faces.

Prefrontal Cortex

• The orbitofrontal cortex (OFC) works with the amygdala in aggression.
• The OFC is involved in rational thinking, decision making, self-control, impulse regulation, and inhibiting aggressive behavior.
• Reduced OFC activity is seen in psychiatric patients with violent tendencies.

Serotonin

• Serotonin is an inhibitory neurotransmitter that slows down neural activity.

• Normal serotonin levels in the OFC support self-control.

• Decreased serotonin levels can lead to reduced self-control and impulsive aggression.

  • Virkkunen et al (1995) found higher levels of a serotonin breakdown product in the cerebrospinal fluid of violent, impulsive offenders.

Dopamine

• Dopamine is both an inhibitory and excitatory neurotransmitter that regulates motivated behavior and reward experiences.

  • Dongju Seo et al (2008) proposed that serotonin underactivity stimulates dopamine overactivity which are both linked to impulsivity and aggression.

Evaluation of Biological Research into Aggression

• Strengths
  • Pardini (2014): Amygdala volume negatively correlated with aggression after controlling extraneous variables.
  • Raine (1997): Classic study establishes link between brain activity and murders
  • Animal research: Electrical stimulation of the hypothalamus can result in aggressive behaviour (Andy and Velamati, 1978)
  • Application: Developing drugs (serenics) to modify serotonin levels could reduce aggressive behavior.
  • Brain scanning technology: PET and fMRI scans are objective methods of measuring brain activity.
  • Case studies (Charles Whitman, Phineas Gage) support the link between brain damage and behavioral changes.
• Weaknesses
  • Reductionist: Ignores social, environmental, and psychological factors.
  • Animal studies: Findings may not generalize to humans.
  • Correlational: Ethical constraints limit experimental research, making it difficult to establish causation.
  • Brain scanning technology: Low ecological validity
  • Counterargument: Drugs that increase serotonin activity (e.g. paroxetine) resulted in participants giving fewer and less intense shocks to others (Berman, 2009).