Motivation

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Motivation
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What are our most basic motivations?

• Temperature regulation
• Thirst
• Hunger
• Self-preservation
• Sleep

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Feedback Systems

• As an organism changes its environment, these
  changes then effect the organism
• Positive feedback system information fed back
  in amplifies the response that produced it
• Negative feedback system information fed back
  in slows or stops the response

4
Homeostasis

• In healthy organisms, internal conditions must
  stay within a narrow range
• Body strives to maintain this internal
  equilibrium, or homeostasis

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Temperature Control

• Two types of temperature control
• Endotherms internal (birds mammals)
• Ectotherms external (reptiles)

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Temperature Control

• Internal control
• Setpoint optimal temp
• Vasodilatation when temp goes to high above
  setpoint, capillaries widen
• Vasoconstriction when temp goes too low,
  capillaries squeeze together
• Piloerection goosebumps
• External control

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What Controls Mechanisms of Temperature
Regulation?

• Autonomic Nervous System (ANS) part of
  peripheral nervous system connected to glands,
  muscles of internal organs, blood vessels
• Sympathetic accelerates heart rate, slows
  peristalsis, vasoconstriction (warm up)
• Parasympathetic slows heart rate, stimulates
  peristalsis, vasodilatation (cool down)

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What Controls Mechanisms of Temperature
Regulation?

• Hypothalamus
• Special neurons called thermoreceptors to sense
  temperature
• Initiates reflexes behavior to warm or cool
• Releases pyrogens at sites of bacterial or viral
  invasion cause change in bodys setpoint

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Hunger

• Basal metabolic rate how fast organisms need to
  burn food to gain the energy and materials they
  need

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What Determines When We Are Hungry vs. Full?

• Signals from the liver
• Glucose blood sugar
• Glycogen glucose converted to starch for
  storage
• When glucose is plentiful being converted,
  signals say full when glucose is scarce and
  glycogen is converted, signals say hungry
• Other signals from the stomach, intestines,
  receptors in the brain

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What Determines When We Are Hungry vs. Full?

• Signals from fatty tissue
• Leptin secreted by fat cellsreceptors in
  hypothalamus
• External signals
• Hunger? Attractiveness of food? Social cues?

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Obesity

• Over 60 of Americans are overweight, 1/3 are
  obese
• Is it simply caloric intake energy expenditure?
• Less efficient digestion
• Lower metabolic level
• Too much conversion to fat

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Obesity

• Genetic Factors
• Weights of identical twins reared together were
  just as similar as those reared apart
• Men kept on same diet, exercise, all gained
  different amounts of weight in different areas
• Evolutionary reasons?

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Treatment of Obesity

• At any time in the US, 40 of women and 25 of
  men are on a diet
• More drastic measures medication surgery
• Is obesity unhealthy?
• Social influences?

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Anorexia Nervosa

• 1 of population in industrialized societies (90
  female)
• Fear of becoming fat, dramatic weight loss,
  compensatory activities
• 10 die of starvation

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Anorexia Nervosa

• What causes Anorexia?
• Societal pressure to be thin?
• Desire to rebel and assert autonomy control
• Organic causes hypothalamus regulatory system
• Genetic predisposition

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Bulimia Nervosa

• Common in college populations
• One sample 19 in women, 5 in men
• Eating binges followed by compensatory purging
• Maintain normal weight

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Bulimia Nervosa

• Complications cardiac kidney problems, damage
  to tooth enamel, depression
• Treatments
• Antidepressants (SSRIs)
• Cognitive-behavior therapy

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Threat

• What mechanism is responsible for our response to
  threat?
• Autonomic Nervous System (ANS) part of
  peripheral nervous system connected to glands,
  muscles of internal organs, blood vessels
• Sympathetic activates body for fight or flight
• Parasympathetic maintains operations in times
  of peace

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Autonomic Nervous System

• Sympathetic
• Dilates pupils
• Accelerates heart rate
• Opens respiratory passages
• Inhibits tear glands, salivation
• Inhibits stomach contractions, digestive
  secretion, intestinal peristalsis
• Relaxes bladder
• Inhibits erection
• Adrenal gland releases norepinephrine

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Autonomic Nervous System

• Parasympathetic
• Constricts pupils
• Inhibits heart rate
• Constricts respiratory passages
• Secretion of tear glands, salivation
• Stomach contractions, digestive secretion,
  intestinal peristalsis
• Contracts bladder
• Erection

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Human Reactions to Threat

• Sympathetic reactions
• Indicators of emotional state
• Galvanic skin response (GSR)
• Polygraph tests

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Brain Control of Threat Reaction

• Limbic system
• Stimulation in cats can produce halloween
  effect
• In humans, stimulation can produce anxiety rage
• Thought to be involved in anxiety disorders

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Pain Endorphins

• Survival function of pain
• Endorphins endogenous pain relievers,
  chemically similar to opiates
• Involved in how placebos work
• Exercise increases endorphin release

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Sleep Waking

• Structures involved
• Subcortical areas mid- and hindbrain
• Cortex especially recognition

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Sleep Physiological Activity

• EEG measures pattern of electrical activity in
  the brain
• Stages of sleep
• Slow-wave sleep (4 stages)
• REM sleep

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REM Sleep

• Active sleep voltage pattern looks more like
  wakefulness
• Occurs for 5 min after 90-100 min of slow-wave
  sleep
• REM rebound after deprivation, we spend more
  time in REM sleep

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Why Do We Need Sleep?

• Amount of sleep we need varies by age
  individual
• Restorative process?
• REM
• Consolidate learning?
• Thermoregulation?
• Eye lubrication?

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Why Do We Need Sleep?

• Circadian rhythm sleep-wake cycle is on a
  24-hour clock
• Clock is controlled by the hypothalamus pineal
  gland (melatonin) set by inputs from the optic
  nerve

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Dreams

• Dreaming occurs in both slow-wave sleep and REM
  sleep but the content is different
• Why dont we experience pain in our dreams?
• Why is it so hard to remember dreams?

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Why Do We Dream?

• Ancient view prophetic
• Freud expression of unconscious wishes and
  urges
• Modern view activation-synthesis hypothesis
• Dreams reflect the brains aroused state during
  REM sleep

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Reward Arousal Level

• Drive-reduction Theory organisms seek a zero
  level of arousal
• Does this seem true?
• What about drugs and addiction?
• Depressants
• Stimulants
• Tolerance withdrawal

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Reward Arousal Level

• Opponent-process theory
• Nervous system counteracts deviations from normal
• If there is a swing in one direction, there will
  be a compensatory swing in the opposite direction
• e.g., drug effects, jumping out of airplanes,
  running

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Reward Biology

• Is there a reward center in the brain?
• Animals will work for electrical stimulation of
  certain areas of the hypothalamus limbic system
  
• Stimulation of the medial forebrain bundle
  stimulates dopamine release in the nucleus
  accumbens reward
• Dopamine blockers reduce this effect
• Cocaine amphetamine