March 28, 2024	PSY 340 Brain and Behavior Class 29: Attack & Escape Behaviors [Outline]

Note that the full Notes contain a great deal of material.
This outline emphasizes the most important points for you to learn.

A. Attack Behaviors!

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

• Experiencing direct abuse in childhood (also, see below for genetic x environmental effect)

• Living in violent neighborhoods

• Exposure to lead in the environment

• Maternal smoking: Male child of mother smoking > 20 cigarettes /day in 3rd trimester has a 2 times greater risk of being arrested for a violent crime in adolescence and young adulthood than son of mother who does not smoke (8%  16% risk)

No single gene has been found strongly connected to aggressive behavior

> Genetic x Environmental Effect: MAO-A, Childhood Trauma, & Aggression

Triple-Imbalance Hypothesis"

• Aggression is associated with (1) high testosterone, (2) low cortisol, and (3) low serotonin levels (see below)
  

5-HIAA (5-hydroxyindoleacetic acid) as index of how much serotonin (5-HT) has been released.

• Serotonin in Nonhuman Animals

• Serotonin in Humans
• Somewhat higher levels of violent behavior in humans is associated with low serotonin turnover, e.g., arson, violent crimes, suicide by violent means or repeated suicide attempts, adolescent and young adult violent crime Why? Serotonin appears to modulate or suppress aggressive impulses.
• Released prisoners with lower levels of serotonin have greater probability of later conviction for violent crime.
  
• By itself, however, low serotonin is not sufficient to make any specific predictions about future behavior of individuals.
  

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.

• The reaction is greater if one is already tense. Thus, startle reflex is often been used as a gauge of fear or anxiety.
  

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

Amygdala

• Amygdala receives information from many sensory & other regions and sends out information to multiple areas as well.

• During the past 20 years, we have learned how central the amygdala is for many aspects of emotion, but particularly regarding the conditions associated with fear and anxiety.

1. Studies in Rats

• Pavlovian Conditioning to Fearful Stimuli

• 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 (bilateral damage to the amygdala in monkeys)

• 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

• 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.

• 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. 
  

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. 

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

 

Patient S.M. (see image above): degeneration of the amygdala: feels no fear & puts self in dangerous situations

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

Post-Traumatic Stress Disorder (PTSD)

• Recollections of event (flashback)
• Nightmares about trauma
• Avoidance of any reminders of the event
• Exaggerated arousal levels (e.g., startle response) to noise and other stimuli
    
• Occurs at least a month after experience of a trauma in which there was serious threat of injury or death or witnessing other people seriously injured or dead.

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).

• Individuals with PTSD tend to have a smaller hippocampus than those who do not suffer it
• PTSD patients often show lower than normal levels of cortisol
  
• If the amygdala is damaged, such individuals tend to have no PTSD.

Relief from Anxiety

1. Pharmacological Relief (Medications).

• Benzodiazepines: include diazepam (Valium®), chlordiazepoxide (Librium®), and alprazolam (Xanax®).
  

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.

• Benzodiazepines seem to suppress various influences that increase the startle reflex
  

• They also induce sleepiness, block epileptic convulsions, and impair memory

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

• Anxieties such as phobias tend to be resistant to new learning.
  

• Children who fear things can sometimes be taught to respond differently by repeated exposure to what they previously feared. Adults are less willing even to undergo such relearning treatment.

• Clinical psychologists have had moderate levels of success in helping those who suffer phobias to relearn less fearful responses.

Memory Reactivation & Reconsolidation

• A promising approach is the use of propanolol {W}, a beta-blocking drug used for many heart-related conditions, but one which also interferes with protein synthesis in the amygdala.