Understanding Basic Motivations & Sleep: Hypothalamus, Thermoregulation, Hunger, Thirst, and Sleep Disorders

1. Basic Motivation & SleepJune 19, 2014

2. BASIC MOTIVATIONS

3. The Hypothalamus • Multiple functions, regulation of ANS • Endocrine – hormones • Body chemistry – samples blood • Water, electrolytes, energy • Feeding, fluid intake • Temperature – body’s thermostat • Sleep

4. The Hypothalamus Responsive to/receives from many sources… • Cardiovascular system • Pheromones • Hormones (metabolism, sex) • Stress • Infection • Feedback from internal organs, ANS

5. THERMOREGULATION

6. Body Temperature • Specific boundary, regardless of external temp • ~98.6 degrees F • Hyperthermia, hypothermia - significant exposure to extreme temp

7. Body Temperature Hypothalamic control (autonomic, behavioral) to maintain setpoint • Heat loss • Sweat, vasodilation • Heat conservation • Piloerection, shivering, conversion of fat, vasoconstriction

8. Fever • Pyrogens (byproduct of infection/immune system) cause rel. of prostagladin E2 (PGE2) • Change setpoint • May speed healing, improve immune defense • Dangerous if uncontrolled (hyperpyrexia)

9. HUNGER & THIRST

10. Hunger & Eating Behavior of eating, consumption of nutrients • Intake what is needed for body (& brain) to function • Regulate deficiency or excess How do we decide: • What to eat, how much (when to stop), when?

11. Hunger & Eating Previous theory – meet a setpoint (metabolic need) Issues for this theory: • Can eat more (or less) than needed • Prevent, rather than respond to energy deficit • Reductions in glucose/fat do not force eating • Evolution – adapt to long term scarcity • Learning, social influence

12. Hunger & Eating • Hormones – control flow of energy (sugars), feedback to hypothalamus • Insulin, glucagon • Leptin – inhibits fat production • Peptides • Signal satiety – resolution of hunger • Amount, content of food

13. Hunger & Eating Previous theory: hypothalamic regions • Control of feeding (LH) and satiety (VMH) • LH lesion – no eating or drinking (death) Issues for this theory • VMH lesion - gain weight, but less hungry • LH lesion - other effects (motor, sensory) • Regulate metabolism, not “hunger”

14. Hunger & Eating • Balance of intake & output - “settling point” • Positive incentive theory • Anticipation of pleasure of eating

15. Thirst • Fluid balance – blood pressure, proper function of renal system • Electrolyte balance (salt) in homeostasis • Feedback to hypothalamus • Motivates fluid intake

16. Disorders of Hunger & Satiety • Prader-Willi– insatiable hunger • No satiety, slow metabolism • Obesity, eating disorders (anorexia, bulimia) • More psychological component (5-HT, DA treatments)

17. SLEEP

18. Function of Sleep We spend more than ¼ of our life sleeping… … Why? What are the benefits of sleep?

19. Function of Sleep Increased risk for attack/predation Energy expense (control & allow for sleep) Two potential explanations… • Recuperation– restore lost energy • Adaptation – conserve energy

20. Sleep Regulation When to sleep? How much? • Presence of food • Predation • Not related to size, level of activity

21. Sleep Regulation Circadian rhythm – “about a day” • Biological rhythms, including sleep/wake • Responds to cues (light/dark) • Present even w/out • Sensitive to shifts (“jet lag”) • Changes w/ development

22. What is Sleep? • Altered state of electrical activity (EEG) • Brain waves • Cycles through stages in a predictable way • Awake/alert – high frequency, low amplitude • Alpha waves – as eyes shut, prepare for sleep

23. What is Sleep? As progress from Stage 1  Stage 4… • Slower waves, decrease in frequency • Slowest at Stage 4 (delta waves) • Cycles 14, 41 several times per night • Subsequent Stage 1 have REM sleep

25. REM Sleep • Rapid eye movements, similar activity to awake • Very different patterns during REM • High cerebral activity, neural firing • Varied autonomic activity

26. REM Sleep • Reduction in overall muscle activity • Neck muscle activity blocked • Postural changes in response to neck position

27. Dreaming Freud defined dreams as repressed wishes… …currently interpreted as random activity, confabulations • Remember dreams if woken during REM • External stimuli can be incorporated • Appear to be in “real time” • Everybody dreams

28. Control of Sleep • Suprachiasmatic nuclei – in hypothalamus • Circadian “clock” • No effect on sleep, but on cycle • Reticular formation (RAS) - throughout brainstem, coordinated nuclei • Coordinate autonomic responses (breathing, heart rate, blood pressure, eye movements, etc.) when shift from wake to sleep

29. Sleep Deprivation • Less, or no sleep • Quickly regain normal rhythm • Short term - more REM than usual on recovery • Long term – more efficient sleep (more slow wave)

30. Sleep Deprivation • Fluctuation in sleepiness • Microsleeps – 2-3 seconds, lowered response • Decrease in mood, vigilance, executive function • No obvious motor deficits • Changes to autonomic, immune function • Not necessarily on health or performance

31. Sleep Disorders Narcolepsy (hypersomnia) - excessive sleep/sleepiness Daytime sleep episodes Cataplexy (loss of muscle tone) Directly into REM Problems in hypothalamic regulation

32. Sleep Disorders Insomnia –initiating, maintaining sleep • Often coexistent w/ depression, stress Sleep paralysis – inability to move Sleep apnea – stop breathing during sleep

33. Sleep Disorders Somnambulism (sleepwalking) • During stage 3 or 4 Somniloquy (sleeptalking) - during any stage Act out dreams - no core-muscle atonia • Problems in control by reticular formation

34. Hormones & Sex

35. Endocrine System

36. Hormones • Endocrine glands • Incl. pituitary, thyroid, gonads (ovaries and testes) • Glands secrete hormones • Chemical messengers • Over distance – circulatory system • Hormones influence behavior • Incl. growth, sex, development…

38. Hormones • Peptide, protein hormones • Steroid hormones – sexual development & behavior • Androgens (testosterone) & estrogens (estradiol) from gonads • No “male” or “female” hormones • Sexual differentiation, development, daily behavior

39. Hormones Organizational effects: long term; development from conception to maturity Enter cell, bind to nucleus, affect gene expression Activational effects: short term; influence reproductive behavior in mature adults

40. Control of Hormones • Endocrine system under control of CNS • Modified by experience • High degree of communication • Cortex, hypothalamus, pituitary, gonads

41. The Pituitary The “master gland” • Release hormones which stimulate further hormone release • Gonadotropins release gonadal hormones

42. The Pituitary Anterior pituitary • Luteinizing hormone • Follicle stimulating hormone Posterior pituitary • Vasopressin • Oxytocin Other non-sex related hormones

43. Pituitary Hormones Luteinizing hormone (LH): triggers ovulation, production of testosterone Follicle-stimulating hormone (FSH): maturation of egg/sperm Oxytocin: bonding, uterine contractions Vasopressin: pair bonding

45. The Pituitary • Female hormone release cyclical (monthly) • Male steady • Both fluctuate daily

47. The Pituitary Pituitary implanted in different gender -- conformed to sex of individual • Suggests higher control of the pituitary… so where is this controlled?

48. The Hypothalamus Influences pituitary hormone release • Posterior pituitary - continuous w/ hypothalamus • Anterior pituitary - release triggered by signals from hypothalamus • Gonads feedback to pituitary, hypothalamus

50. Sexual Differentiation