Lecture3 psych125 bunge

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Prenatal Brain Development

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  • Monkey measurements done by labeling for radioactive glucose.
  • Association areas function to produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language.The association areas integrate information from different receptors or sensory areas and relate the information to past experiences. Then the brain makes a decision and sends nerve impulses to the motor areas to give responses. [20]
  • Pride & joy of the human brain. The frontal lobe or prefrontal association complex is involved in planning, controlling thoughts, actions, & emotions, as well as abstract thought.
  • Association areas function to produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language.The association areas integrate information from different receptors or sensory areas and relate the information to past experiences. Then the brain makes a decision and sends nerve impulses to the motor areas to give responses. [20]
  • Seminal event --- pun intended ---
  • Of the 200-300 million sperm normally deposited in female genital tract, only 300-500 reach site of fertilization, and generally only 1 fertilizes egg; thus, chance of fertilizing egg is roughly 1:300 million (chances of carrying zygote to term less than that)
  • The moment that human life begins? Depends on your beliefs.
  • At 4 weeks after conception, the embryo ’s tiny body is curved so tightly that the head and tail-like structure at the other end are almost touhing. The round area near the top of the head is where the eye will form the round gray area near the back of the ‘neck’ is the primordial inner ear. A primitive heart is visible – it is already beating and circulating blood. An arm bud can be seen in the side of the embryo. A leg bud is present but less distinct.
  • In the 5.5-week-od fetus, the nose, mouth, and palate are beginning to differentiate into separate structures. just 3 weeks later, the nose and mouth are almost fully formed.
  • Rudimentary eyes and ears are forming. All of the internal organs are present. Sexual differentiation has started. Fingers and toes have emerged, and nails are growing. Spontaneous movements occur, but can ’t be felt by the mother.
  • This picture was created by non-invasive 3-D imaging!
  • Sucking thumb
  • The weight cut-offs we use are LBW < 2500, VLBW < 1500, ELBW(extremely low birth weight) < 1000. weight in proportion to gestational age is also important. Infants who are either small or large for their gestational age are at risk for certain medical complications after birth (i.e. low blood sugar, temp instability, certain infections can affect birth weight (CMV causes low birth weight). LGA (large for gestation age) > 90%, AGA (average) 10-90%, SGA (small) <10% according to gestational age.
  • Lecture3 psych125 bunge

    1. 1. PSYCH 125, Lecture 3Functional Brain Anatomy & PrenatalDevelopment
    2. 2. Question for discussion in sectionThe human brain takes years to mature, consumes 30% of thebody’s energy, and has gotten so large that unassistedchildbirth is dangerous.What important function(s) does the brain serve, beyond whatthe spinal cord & brain stem can accomplish?
    3. 3. ReviewOne way to subdivide the brain is according toanatomical features – either macroscopic ones (sulci,gyri) or microscopic ones (appearance of cells & celllayers under microscope)•What’s another way to subdivide the brain?•Which techniques can we use in humans to figure outwhat a brain region does?
    4. 4. Topographic organization in primary motor &somatosensory cortices (Penfield, 1940s-50s)
    5. 5. Primary visual cortexLateral View Medial View W. W. Norton
    6. 6. Retinotopy in Primary Visual Cortex• injected radioactive glucose into bloodstream while monkey viewedimage• “developed” brain like a photograph• Map of retina reproduced in brain! Roger Tootell et al., 1988
    7. 7. Visual processing Two processing streams (pathways):1. “What”: object recognition (ventral stream = occipito-temporal)2. “Where”: spatial localization (dorsal stream = occipito-parietal) (or “How”: how to act w/r to an object) W. W. Norton
    8. 8. Tonotopy in Primary Auditory Cortex
    9. 9. Primary, secondary, and associationcortices Primary cortex Secondary cortex Association cortex W. W. Norton
    10. 10. Frontal cortex: Goal-directed behavior
    11. 11. QuizA. B. C. Which of these lobes would play the biggest role in… •deciding which of two courses to take? •finding your way to the classroom? •remembering facts that you learned in class?
    12. 12. PollWhat does ‘topography’ mean, in the context of thebrain?A) A map of the gyri and sulci of the brainB) The spatial organization of cytoarchitectonic regionsC) The fact that frequencies of sound are representedin a systematic way across primary auditory cortexD) The ordered projection of a sensory surface, like theretina or the skin, or an effector system, like themusculature, to the brain
    13. 13. Poll: Which box represents the sense ofhearing? B A C D Primary cortex Secondary cortex Association cortex W. W. Norton
    14. 14. Next upPrenatal brain development 9 months http://capturedbycarrie.com/
    15. 15. 200-300 million sperm deposited – only 1 (if any) will fertilize theegg
    16. 16. That one lucky little spermatozoid
    17. 17. Formation of the embryo
    18. 18. Early stages of embryonic development Inner cell mass will Formation of thereorganize into a disk 3 germ layers
    19. 19. Germ layers
    20. 20. The Ectodermal germ layer will give rise to… • Central Nervous System • Peripheral Nervous System • Sensory epithelium of ear, nose, and eye • Skin (including hair and nails) • Pituitary, mammary and sweat glands • Enamel of teeth• Important gene for ectodermal development: Growth factor BMP4 22
    21. 21. Formation of the neural tube thebrain.mcgill.ca
    22. 22. Week 4: From neural tube to brain andspinal cord
    23. 23. Neural tube defects Humpath.com
    24. 24. Regionalization of the brain Prof. Thomas Jessell, researchchannel.org
    25. 25. From 1 month after fertilization through birth Prof. Thomas Jessell, researchchannel.org
    26. 26. Face development from 5.5 weeks to 8.5weeks• Facial structures fuse during the 7th week• Cleft palate (1 in 500 births) develops from errors during this period
    27. 27. 9 weeks• Around the size of a peanut• Head is roughly half the length – bulging forehead reflectsextremely rapid brain growth that has been going on forweeks
    28. 28. 11 weeks: major divisions of brain are visible
    29. 29. 16 weeks• can tell the sex of the fetus• kicking & some reflexes (breathing movements, grasping, sucking)
    30. 30. 18 weeks
    31. 31. 20 weeks • sleep/wake cycles • facial expressions (eyebrows, forehead, mouth) • head-down position more frequent
    32. 32. 28 weeks • eyelids flutter during REM sleep • reacts to sounds • brain waves similar to newborn • brain and lungs sufficiently developed that – if born now – could potentially survive without medical intervention.
    33. 33. The home stretch: 8th-9th month • Red, wrinkled skin fills out with fat (provides insulation to protect against heat loss) • Gains 1/2 lb. per week • Startle reflex is present; responds to light and sound, lifts its head • 60 percent of adult head size present36
    34. 34. Birth• Considered full-term if born within 10-14 days of calculated delivery date; if born earlier, considered pre-term• The earlier born, the greater the risk (due to underdevelopment)• Correlated with prematurity is low birth weight, which brings its own set of complications and risk • Normal birth weight >3500 grams • LBW <2500 grams • VLBW <2500 grams • ELBW <1000 grams 37
    35. 35. Milestones in prenatal development• Zygote forms after conception• Blastocyst embeds in uterine wall• Germinal stage gives rise to embryonic stage, which lasts about 8 weeks; during this time all organs, systems, etc. form• Fetal stage lasts 7 months (in full term pregnancy) and is period of elaboration and growth• Labor and delivery culmination of all this hard work – generally, 40 weeks post conception Sadler, TW (2010). Medical Embryology, Eleventh 38 38 Edition. Baltimore: Lippincott Williams & Wilkins
    36. 36. When do abortions occur? Percentage of 2008 Reported Abortions by Weeks of Gestation* (CDC)
    37. 37. Who is having abortions?• At current rates, nearly one-third of American women will have an abortion (AGI)• 50% of U.S. women obtaining abortions are younger than 25; women aged 20-24 obtain 33% of all U.S. abortions and teenagers obtain 17% (AGI).• The abortion rate of women with Medicaid coverage is three times as high as that of other women (NAF).

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