Amygdala and Emotions Quiz

Sex vs Gender

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Amygdala & Emotions

• The amygdala responds to the ambiguity of stimuli
• The amygdala reacts to pleasant stimuli, but not very strongly
• Strong amygdala activation by fear-inducing stimuli
• The amygdala's response is very fast
• The amygdala reacts more strongly when a stimulus is more difficult to interpret

Dysfunctional Amygdala

• Patient S.M: a woman with no fear
• Studies of monkeys (Klüver-Bucy Syndrome): no fear response
• Toxoplasma gondii: a parasite that damages the amygdala in rats/mice
• The amygdala and attention: the amygdala responds to the ambiguity of stimuli

Emotions and Autonomic Arousal

• Sympathetic nervous system: Fight or Flight (stimulates organs important for vigorous activities and inhibits vegetative activities)
• Parasympathetic nervous system: Rest and Digest (increases digestion and other processes that save energy)
• A danger doesn't always elicit sympathetic activity
• James-Lange theory: physiological arousal is necessary for emotional feelings
• Examining the James-Lange theory: autonomic responses are not always necessary for subjective experiences

The Limbic System & Basic Emotions

• The limbic system has been regarded as the key brain system involved in emotions
• A certain group of neurons seem to be specific for perceiving a particular emotion in others
• No specific brain area can be linked to experiencing specific emotions
• Understanding emotions as a continuum rather than categories

The Functions of Emotions

• Emotional expressions help us communicate our needs to others and understand other people's needs
• Being able to communicate emotions effectively might have given our ancestors a clear advantage over other primates (the cooperative eye hypothesis)

The Ventromedial PFC & Moral Decision making

• In the Dictator game, one player is given a sum of money to divide with another player
• People in general share evenly
• People with damaged ventromedial PFC keep about 90%
• PFC damage in general leads to impulsive decision-making without consideration for others or consequences

Oxytocin & Emotional Contagion

• Oxytocin enhances emotional contagion and facilitates helping behavior

Attack Behaviours

• In the resident--intruder test, the resident's probability of attacking the intruder increases if another intruder is introduced within a short time
• The activity in the amygdala builds up after the first resident-intruder encounter

Genes * Environment on Aggression Behaviour

• There are no known genes that strongly influence aggression
• MAOA gene---low activity form shows a link to aggression
• The effect of the polymorphism is moderated by environmental factors

Hormonal Effects

• Aggressive behaviour in males heavily depends on testosterone
• Testosterone facilitates aggression
• Serotonin inhibits impulsive behaviour
• Cortisol inhibits aggression

The Effect of Behavioural Intervention on Testosterone

• It seems that it is the rapid increase in testosterone level rather than the baseline level which is linked with aggressive behaviours
• Early intervention in a high-risk group moderates the level of aggression as well as testosterone response in adulthood

Anxiety Disorders

• Anxiety disorders are the most frequently seen mental disorders in primary care
• General Anxiety Disorder: excessive anxiety and worries
• The constant worrying causes clinically significant distress or impairment in daily life

Animal Models of Generalised Anxiety Disorder

• After a cued fear conditioning, an animal develops fear response not only for the cue but also the context
• The animal also often displays more anxiety-like behaviour in a novel environment as well
• Depending on the situation, generalised anxiety effectively prepares an individual to deal with dangers

Panic Disorder

• Affects about 2-3% of the population each year in NZ
• Risk factors: Stress, Genetics (40% concordance rate in MZ), other psychiatric disorders
• The neurobiological mechanisms

How Does Benzodiazepine Work?

• Benzodiazepines (Valium, Xanax) bind to the GABA receptor
• GABA molecules cause hyperpolarization of neurons (Inhibitory)
• Benzodiazepines do not open the chloride channels directly, but it changes the receptor structure in such a way that GABA molecules bind more easily to the receptors

Hippocampus, Striatum, and Memory

• Bilateral Medial Temporal Lobectomy: remove hippocampus on both sides
• H.M Case: anterograde amnesia, retrograde amnesia, severe impairment in episodic memory, short-term/working memory intact, intact procedural memory, better implicit than explicit memory, able to form new weak semantic memories

What Would it Feel Like Having an Amnesia Like Henry Molaison?

• Every book, TV shows remain novel -- always
• You meet new people every day
• It feels like people include strange words that you can't understand
• You can't imagine any future event -- consider the evolutionary advantage of having episodic memories

Modelling Episodic Memory in Animals

• The animal needs to remember the when and what to choose a correct answer
• Lesions in the hippocampus impair the performance drastically
• Hippocampus' role as the coordinator of memory for context

The Striatum

• Involved in the gradual, probabilistic learning process
• Damages in the striatum (e.g., Parkinson's disease) impairs probabilistic learning
• People with hippocampal damage can acquire probabilistic learning after many attempts

Depression

• The severity of anhedonia is a more reliable symptom than increased sadness
• More common in women
• Ethnic inequality in diagnosis (Lee et al, 2017)
• Largely two groups of patients (early onset vs. late onset)
• Many patients do not get relief from current therapeutic options

The Genetic Risks of Depression

• A moderate degree of heritability
• SERT polymorphism and environment interaction
• Why the vulnerable genotype survived:
  1. Adaptability: s variant has been associated with a heightened sensitivity to both positive and negative environmental influences
  2. Increased emotional responsiveness

Different Types of Antidepressants

• Discovery of the first antidepressants in the 1950s
• Unexpected antidepressant effect from the drugs originally used to treat tuberculosis and psychosis
• MAOI (Monoamine Oxidase Inhibitor): inhibit the breakdown of monoamines
• TCAs (Tricyclic Antidepressants): block reuptake of norepinephrine
• SNRIs (Serotonin and Norepinephrine Reuptake Blocker)
• SSRIs (Selective Serotonin Reuptake inhibitors): block reuptake of serotonin only

The Serotonin Paradox

• Normal 5-HT level in people with depression
• People with s/s SERT genotype have a higher level of 5-HT!