Module 12: Emotion, Stress, and food

Theories on Emotion

James-Lange, Cannon-Bard, Modern Biopsychosocial View

James-Lange Theory

Emotion as a result of body response; ex: seeing a bear: you tremble and your heart races, and then your brain interprets these physical changes as fear

Cannon-Bard Theory

Body and emotion are parallel; ex: seeing a snake might prompt both the feeling of fear (an emotional response) and a racing heartbeat (a physical reaction).

Modern Biopsychological View on Emotion

More evidence that these elements interact with each other

Ekman & Friesen's (1975) Primary Facial Expressions

Fear, surprise, disgust, anger, sadness, and joy

Fear and Disgust

Defensive behaviors; they are designed to preserve your safety

Anger

Aggressive behavior, its main purpose is to inflict harm on others

Limbic System

"Thalamus and friends"; main function relates to the experience and expression of emotion

Key Areas of the Limbic System

Amygdala, Corpus Callosum, Hippocampus, Mamillary Bodies

Amygdala Studies

Studies on fear-inducing sounds found that nervous signals indicating fear route through the amygdala

Amygdala

Receives sensory inputs and assigns them the appropriate emotional significance/response

Medial Prefrontal Cortex

responsible for higher cognitive processes; conscious cognitive suppression/re-evaluation of emotional response (supports the modern view of emotion)

Stress

Set of physiological changes brought about by either psychological or physical stressors

Two-System View of the Human Stress Response

Highlights the body's division of labor between an immediate, fast-acting response and a slower, sustained hormonal response

View of the Human Stress Response

Sympathetic NS -> Adrenal medulla -> Norepinephrine and adrenaline

View of the Human Stress Response

Pituitary Gland -> Adrenal cortex -> Glucocorticoids

Efferent pathway of the Autonomic division

Controls most involuntary bodily functions; parasympathetics NS and sympathetic NS

Parasympathetic Nervous System

Involuntary actions that relax, prepare, or conserve energy

Sympathetic Nervous System

Involuntary actions that tense, activate, or release energy

Glucocorticoids

Hormone responsible for the stress response of the body

Induction of Stressors

Make the body produce a class of hormones called glucocorticoids

Cortisol

AKA hydrocortisone; most important stress hormone in humans that increases blood glucose and reduces inflammation to prepare for a stress-induced environment

Prolonged Stress

Leads to maladaptive behavior and body changes

Stress Effects on the Hippocampus

Stress has been found to damage the ability of neurons to connect in the hippocampus due to corticosterone

Hippocampus

An area of the brain associated with episodic memories

Insulin

Produced by the pancreas and regulates blood sugar levels

Glucagon

Counteracts insulin; promotes turning fat/protein/glycogen into blood glucose

Insulin

Converting excess sugars → fat and glycogen

Insulin

Converting amino acids → proteins

Insulin

Storage of fat in adipose, protein in muscle, glycogen in liver

Stages of Metabolism

Cephalic -> Absorptive Stage -> Fasting Stage

Cephalic Stage

HIGH insulin; Preparation to eat food

Absorptive Stage

HIGH insulin; Food being eaten fulfills body needs

Fasting Stage

LOW insulin; Stored fat and nutrients fulfills body needs

Theories on Hunger

Set Point Assumption Theories & Positive-incentive Theories

Set Point Assumption Theories

Insufficient Glucose Level and Deviation in Body Fat; When fat stores drop, hunger increases to stimulate eating; if weight exceeds this point, metabolism increases, and hunger decreases, defending against deviations

Positive-incentive Theories

Evolved craving

Bitter Taste

Indicative of toxins or undesirable chemicals

Impact of Cuisine

Some cultures may like the taste of certain bacterial growths on meat or diary

Calories

Animals develop a taste for materials that lead to an influx of calories; We are attracted to foods with a lot of sugar and carbohydrates

Cause of Hunger

Hunger is due to our body expecting an influx of food at certain times, and prepares itself for the incoming nutrition

Satiety

The feeling of fullness we experience after eating; depend on volume and nutrient density of the food that was taken

Leaky Barrel Model of Body-Weight Homeostasis

Explain how human body weight is regulated, arguing that weight is managed through a "settling point" mechanism rather than a rigid set-point.

Amount of Water Entering the Hose

Analogous to amount of available food

Water Pressure at the Nozzle

Analogous to the incentive value of the available food

Amount of Water Entering the Barrel

Analogous to the level of body fat

Amount of Water Leaking from the Barrel

Analogous to the amount of energy being expended

Weight of the Barrel o the Hose

Analogous to the strength of the satiety signal

Common Eating Disorders

Anorexia Nervosa and Bulimia Nervosa

Anorexia Nervosa

Chronic attempts at fasting and weight loss due to a misconception of body image

Bulimia Nervosa

A pattern of binge-eating and voluntarily induced vomiting in order to sate cravings and maintain body image