Stress, Emotions, and Health - Lecture Notes

Biopsychology of Emotions

• Early Landmarks in the Biopsychological Investigation of Emotion

  • Case of Phineas Gage (1848)

  • Darwin's theory of the evolution of emotion (1872)

  • James-Lange and Cannon-Bard theories (about 1900)

  • Discovery of sham rage (1929)

  • Discovery of Klüver-Bucy syndrome (1939)

  • Limbic system theory of emotion (1952)

• Cognitive neuroscience studies the neural and biological basis of emotional processes.

  • It has established that there is not one brain region involved in the experience of a specific emotion.

Brain Mechanisms of Human Emotion

• The limbic system is composed of several brain structures involved in behavioural and emotional responses, including fight or flight.

  • The two major components of the limbic system are the hippocampus and amygdala, but there are others.

• The amygdala is located adjacent to the hippocampus and is significant in the experience of emotions.

  • New memories associated with an emotional response are more likely to be recalled (e.g., relating to fear).

• A neutral auditory cue paired with a naturally aversive stimulus can produce a fear response through auditory fear conditioning.

  • Fear = biological response to immediate danger or perceived threat.

  • Anxiety = worry about a threat.

• The medial prefrontal lobes exert cognitive control over emotional processing through its interactions with the amygdala.

The Expression and Regulation of Emotions

• Ekman and colleagues proposed six basic emotions which are universal and suggested that these had a genetic basis.

  • However, there are other models of emotion (e.g., Plutchik’s theory).

• A reduction in the facial expression of emotions (or blunted affect) is observed in different psychiatric disorders (e.g., major depressive disorder).

  • There are also impairments in facial emotion recognition.

• Emotion regulation occurs where an individual shapes which emotions they have, when they have them, and how they are expressed and experienced with the intention of achieving our goals (Gross, 2014).

  • Explicit emotion regulation = dlPFC, vlPFC

  • Implicit emotion regulation = vmPFC

• Different brain regions may be associated with specific emotion regulation strategies.

• There are four key components of dialectical behaviour therapy (DBT).

  1. Interpersonal effectiveness

  2. Mindfulness

  3. Emotion regulation

  4. Distress tolerance

• It was designed to treat the strong emotional experiences in individuals with Borderline Personality Disorder (BPD).

• Several brain regions demonstrate reduced activity following DBT in individuals with a BPD diagnosis.

  • These include the amygdala and hippocampus.

Stress and Health

• Stress is experienced in response to a real or perceived threat (a stressor).

  • Once a stressor is identified, an emergency reaction is triggered in response to a threat to homeostasis.

  • The evaluation of whether a stimulus is a real or potential threat occurs via several brain structures.

  • Different brain structures are involved depending on which type of stressor is involved.

• Two Main Types of Stressors:

  • Perceived threats or psychological stressors (i.e., situations that can potentially lead to danger). For example, having a heavy workload.

  • Internal threats or systemic stressors (i.e., physical changes in the body). For example, hypoglycemia.

  • ‘Eustress’ is a positive stress response which can be beneficial in achieving outcomes.

• The Stress Response:

  • Brain triggers the sympathetic nervous system and the anterior pituitary.

  • The sympathetic nervous system triggers the adrenal medulla to release norepinephrine and epinephrine.

  • The anterior pituitary triggers the adrenal cortex to release glucocorticoids.

  • These mechanisms promote homeostasis.

• SAM = sympathetic adrenal medullary axis

• HPA = hypothalamic adrenal axis

• The Hypothalamic Pituitary Adrenal Axis initiates the body’s main response to stress. It is composed of the:

  1. Hypothalamus

  2. Pituitary glands

  3. Adrenal glands

• Chronic stress and prolonged activation of the HPA axis can affect the functioning of several body systems.

• Chronic activation of the HPA axis speeds up the development of symptoms in AD and associated cognitive impairment occurring where there is a genetic predisposition.

• There are several mechanisms through which stress affects the immune system (e.g., T and B cells have receptors for gluticosteroids).

  • Behavioural changes are also important (e.g., diet, sleep).

• Glutocosteroid release via the HPA axis produces gastric ulcers.

• The brain-gut axis is a network that links that enteric (or gastrointestinal) and central nervous systems.

• An important component of the brain-gut axis are the gut microbiota.

  • Gut bacteria stimulate neurons of the enteric nervous system which send signals to the brain via the vagus nerve.

• The gut-brain axis has been associated with psychiatric disorders, although inconsistently.

• The Brain-Gut Axis Interacts with the Immune System

Adaptive Strategies for Coping with Stress

• Try to reduce your experience of stress (e.g., ask for help, reduce your standards)

• Improve your resilience to stress by having strong social support

• Aim to have a diet that is high in nutrients

• Relax your muscles (e.g., through progressive muscle relaxation)

• Meditate and relax (which can also help with insomnia)

• Continue to engage in activities that you enjoy

• Reframe your thinking