Anger, Aggression, and Impulse Control

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Anger, Aggression, and Impulse Control

• Presented by
• Traci Leach
• Ben Schweitzer
• Ciara McCaffrey

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Introduction

• Aggressive behaviors are species-typical
• Patterns of movements are organized by neural
  circuits
• Aggressive behaviors are often related to
  reproduction
• Types of aggressive behaviors include
• Threat Behaviors- posture gestures to warn the
  adversary to leave it will become the target of
  an attack
• Defensive Behaviors- threat behaviors or an
  attack against the animal that is threatening
• Submissive Behaviors- accepting defeat and will
  not challenge the other animal

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Research with Laboratory Animals

• Neural control of aggressive behavior is
  hierarchical
• Whether an animal attacks depends on neural
  circuits in the brain stem
• Brain stem is controlled by the hypothalamus and
  amygdala
• When studying aggressive behaviors in cats, it
  was determined that 3 regions of the amygdala and
  2 regions of the hypothalamus affect defensive
  rage and predation

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The Role of Serotonin

• Serotonergic neurons have an inhibitory effect on
  risky and aggressive behavior
• A study with rhesus monkeys showed that lower
  levels of serotonin were associated with higher
  risk-taking behavior
• Drugs that act as serotonin agonists have been
  shown to reduce irritability and aggressiveness
• Differences in the serotonin transporter gene
  have been associated with varying reactions of
  peoples amygdala when viewing facial expressions
  of negative emotions

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The Role of the Ventromedial Prefrontal Cortex

• This region of the prefrontal cortex is located
  at the base of the anterior frontal lobes,
  neighboring the midline.
• It receives information from the dorsomedial
  thalamus, temporal cortex, ventral tegmental
  area, olfactory system, and amygdala.
• The vmPFC sends information to several regions of
  the brain, including the cingulated cortex,
  hippocampal formation, temporal cortex, lateral
  hypothalamus, and amygdala. All of this complex
  communication provides information about the
  surrounding environment.  
• This section of the brain is heavily responsible
  for regulating how we respond to emotional
  situations 
• It specifically inhibits violent behavior
  provoked by the amygdala by accentuating the
  negative consequences associated with it.

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What Happens When the Ventromedial Prefrontal
Cortex is Damaged?

• Emotional behavior is directly impacted if the
  vmPFC is damaged.
• Perhaps the most famous example of this occurred
  in the case of Phineas Gage, a foreman of a
  railway construction crew. In 1848, he was using
  a steel rod to apply blasting powder into a hole.
  Unexpectedly, the charge exploded and the steel
  rod entered his cheek, through his brain, and out
  the top of his skull. Although he survived, his
  personality completely changed. Before the
  accident, he was described as being serious and
  responsible. His vmPFC had been destroyed as a
  result of the incident. For the remainder of his
  life, he was prone to emotional outbursts and
  seemed incapable of controlling his temper.
• The vmPFC is largely responsible for balancing
  the relationship between the automatic emotional
  responses regulated by the amygdala and the
  neural mechanisms involved in controlling complex
  behaviors. Patients with damage to this region
  have numerous emotional dysfunctions and
  impairment in real-world competencies. Damage to
  the vmPFC plays a large role in the formation of
  moral judgment

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Phineas Gage and his tamping iron
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Treatment

• Impulsive Aggression has been successfully
  treated using Serotonin Reuptake Inhibitors a
  common example being Fluxetine or Prozac
• Serotonin Reuptake Inhibitors increase the
  activity of the prefrontal cortex and have shown
  to reduce aggressive behavior