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April 15, 2021

[Brain Image]    

PSY 340 Brain and Behavior

Class 28: Attack & Escape Behaviors [Outline]

   
[Attack...Escape]

A. Attack Behaviors!

Behavior = Violence, fighting, or aggression, but

Emotions = anger, rage, fury, resentment, hostility, etc.

What are the Environmental and Heredity Factors which have been shown to lead toward violence?

   Environmental Factors
Lead vs. Murder
   Genetic factors
No single gene has been found strongly connected to aggressive behavior
> Genetic x Environmental Effect: MAO-A, Childhood Trauma, & Aggression

MAOA and Early
                Trauma

Emotional Reactivity
    Effects of Hormones: Testosterone
   Serotonin Synapses & Aggressive Behavior
5-HIAA (5-hydroxyindoleacetic acid) as index of how much serotonin (5-HT) has been released.
        Low serotonin turnover = a relative decrease in the amount of serotonin released and taken back into the pre-synaptic neuron.

Summary: There appears to be some relationship between increased violence and various biological functions (hormones, low serotonin, genetic x environmental interactions). But

B. Escape! Behaviors: Fear and Anxiety

Fear, Anxiety, and the Amygdala

Loud noise = startle reflex (present in babies, too) which occurs 2/10th of a second after the sound. Muscles of neck tense up.

Basal GangliaJoseph LeDoux at New York University has focused upon the role of the amygdala in the formation of emotional responses.

[Temporal Lobe]

Amygdala

[Amygdala Connections]

1. Studies in Rats

  • Conditioned stimulus (CS, e.g. bell) paired with an unconditioned stimulus (UCS, e.g., electrical shock) leads eventually to the development of a conditioned response (CR), i.e., fearfulness.
  • Learning takes place via changes of cell connections in the lateral amygdala
  • Damage to the amygdala interferes with learning fearfulness
  • Implications: Changes in the amygdala are implicated in human anxiety problems such as PTSD, phobias, & panic disorder. It may become overly sensitive to threats in the environment.

2. Studies in Monkeys

Klüver-Bucy Syndrome

  • Taming: Placid, loss of aggression
  • Psychic Blindness: Inability to recognize objects by sight: No longer fear stimuli such as snakes
  • Responsiveness to many small visual cues ("hypermetamorphosis" [Danek, 2007])
  • Hyperorality: Examine objects by licking, biting, & chewing
  • Hypersexuality
3. Studies in Humans
PET & fMRI: Increased activity in amygdala to pictures of faces showing strong emotions, e.g., fearful, angry, happy

Amygdala will signal the ANS even if shown emotional images too quickly to be consciously comprehended
  • [Thalamic-Cortical Tracts & Amygdala]Originally LeDoux spoke of two "roads" by which we respond to emotional (NOT just FEARFUL) information
    • "high road" through the sensory cortex which provides conscious (explicit) recognition after 30-40 ms
    • "low road" directly from the thalamus to the amygdala at an unconscious (implicit) level of processing within 12 ms

Emotion as a Conscious Cognitive State. S

  •  that the amygdala is one of several "defensive survival circuits [that] are evolutionarily wired to detect and respond to innate threats and to respond to novel threats that have been learned about in the past.
  • Defensive survival circuits indirectly contribute to the feeling of fear, but their activity does not constitute fear"
  • Both fear (an emotion that responds to a threat NOW) and anxiety (an emotion that responds to a threat in the FUTURE) only become real when we become conscious of the threat and of our unconscious responses. 

Newer LeDoux
                model

his August 2017 talk at the APA meeting in DC):

  • In this model, the experience of fear (or any other emotion) arises in our conscious working memory from multiple elements that are processed in our working memory at an unconscious level. 
LeDoux Diagram

Urbach-Wiethe Disease [aka Lipoid proteinosis] (Siebert, Markowitch, & Bartel, 2003)
SM Amygdala  Facial Expression

Patient S.M.
Conclusion: Amygdala seems to be deeply involved in the processing and interpretation of sensory stimuli for its emotional importance or meaning. This means that the amygdala is involved in more than just fear!

C. Anxiety Disorders
Anxiety disorders include generalized anxiety disorder, panic disorder, phobias, and post-traumatic stress disorder (PTSD).

Panic Disorder
OK City Bombing 1996Post-Traumatic Stress Disorder (PTSD)

Events include soldiering in war, rape, severe automobile accidents, torture, exposure to natural or human-caused disasters (e.g., Oklahoma City Bombing, 9/11, or the Boston Marathon bombing).

Most people exposed to serious trauma do not develop PTSD (that is, <50% exposed to serious trauma actually develop PTSD).

[Valium]Relief from Anxiety

1. Pharmacological Relief (Medications).
[GABAa Receptor Complex Diagram]GABA-A receptor complex
  
Benzodiazepines which bind to GABA-nergic sites in the amygdala appear to decrease overall levels of anxiety and fearfulness. How? This may be due to the drug's ability to block the amygdala's processing of fear-inducing information or stimuli.


[Budweiser Beer
              Can]2. Alcohol as an Anxiety Reducer. Another chemical which binds to the GABA-A complex is ethyl alcohol (ethanol)..

Hoffmann-LaRoche developed a drug, Ro15-4513, which blocks many of the effects of alcohol (it functions as an inverse agonist to GABA).

3. Relearning to Erase Anxiety

Memory Reactivation & Reconsolidation