Lecture 11a: Intro to Affective Neuroscience (The Emotion System)

Folk Notion (Common-Sense Theory)

Emotions cause automatic reactions

James-Lange Theory

Automatic reactions trigger feelings

Cannon-Bard Theory

Simultaneous emotional experience and physiological reaction

Schachter-Singer Two-Factor Theory

Cognitive attribution of emotion to arousal

stimulus - physiological response - emotional response - interpretation

Internal Experience

Feelings (happy, anxious, sad)

External Experience

Behaviours (smiling, fidgeting, shouting)

Autonomic Nervous System

Activation leads to physical sensations associated with emotions

• Sympathetic and Parasympathetic Nervous System

Sympatheric Nervous System

Prepares body for fight-or-flight response

Parasympathetic Nervous System

Prepares body for rest and recuperation (rest-and-digest)

Limbic System

Group of brain structures crucial for regulating emotions and plays a key role in the formation of neural chemicals and memories

• Amygdala: processing emotions (particularily fear)

• Hypothalamus: manages physical responses to emotions

• Hippocampus: involved in memory preservation and retrieval relevant to emotional experiences

Papez

Lesions in the limbic system would impair emotional processing

Cognitive vs. Affective

• Cognitive: understanding other's’ emotion

• Affective: sharong others’ emotion

Stress

A multidimensional process involving stress stimuli, processing, and physiological/behavioural responses

Role of Hypothalamus in Stress

Key in stress detection and response regulation

Allostasis

Brain’s adjustment of the body’s physiological state in response to stressors

Stress Response Stages

1. Alarm Reaction

2. HPA Axis Activation

3. Adaptation

Alarm Reaction

Immediate response, activation of the sympathetic nervous system, release of epinephrine (adrenaline) and norepinephrine (nonadrenaline) from adrenal medulla

HPA Axis Activation

Longer-term stress response involving the hypothalamus stimulatinf the anterior pituitary and ACTH triggering the adrenal cortex to relase cortisol

Adaptation

Adjusting to ongoing stressors

Hormones Involved in Stress

• Epinephrine and Norepinephrine

• Cortisol

• ACTH (Adrenocorticotropic Hormone)

• Glucocorticoid Receptors

Epinephrine and Norepinephrine

Increase heart rate and prepare the body for immediate action

Cortisol

A steroid hormone that helps regulate metabolims and immune responses (can cause damage in excess)

ACTH (Adrenocorticotropic Hormone)

Triggers cortisol production from the adrenal glands

Glucocorticoid Receptors

Found in the brain; regulate cortisol levels and influence memory and learning

Long-Term Effects of Stress

• Increased cortisol levels impacting memory and learning

• Structural changes in key brain regions

  • Shrink the hippocampus

  • Heightein amygdala activity

  • Impair prefrontal cortex function

• Higher risks for anxiety, depression, and cognitive decline