Development Spring 2009 PV

Development Spring - Biological Development Endocrine Messengers – Hormones Chemical messengers released into the bloodstream to exert an effect

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Unformatted text preview: Biological Development Endocrine Messengers – Hormones: Chemical messengers released into the bloodstream to exert an effect on a distant target. – Pheromones: Chemicals released into the environment to act on members of the same species. Major Endocrine Structures • Hypothalamus-Pituitary: “Master Gland” • Metabolism – Thyroid: metabolism, growth, – Adrenals: carbohydrate metabolism – Pancreas: regulates sugar metabolism via insulin release. • Sexual development and behavior: – Gonads (Testes, Ovaries) Hypothalamus Releasing Factor Anterior Pituitary “Triggering” Hormone Target Organ Sex Hormones (Into Bloodstream) When you were just a twinkle in your daddy’s eye… Gonadotropin Effects in Males: • LH surge increases the production and release of T from the testicles. • FSH surge fuels spermatogenesis. – The production of mature male gametes Gonadotropin Effects in Females: • Serve to regulate menses – Days 1-4: FSH levels increase, stimulating the follicle (egg) to develop and grow – Around Day 14: Estrogen reaches a critical level and initiates LH surge. • LH mediates ovulation • The follicle is now termed a “corpus luteum.” Human Menses (Cont’d) • If fertilized, CL synthesizes corticogonadotropic hormone – HCG in humans – Stimulates corpus luteum to keep on secreting progesterone Part II Nervous System Development Early Embryo • Fertilized Ovum • Blastula – Post-conception Weeks 1 and 2 – Sphere of about 128 cells surrounding a fluid-filled cavity • Gastrula – Third week post-conception – Organizes into three distinct cell layers Gastrulation: The Development of the Ectoderm, Mesoderm and Endoderm The nervous system will develop from the ectoderm—the outermost cell layer. Gastrulation: “The Embryo Takes Shape” • http://www.pbs.org/wgbh/nova/miracle/program.html Neurulation: Development of the Neural Plate, Neural Crest, and Neural Tube The neural crest rises on both sides And eventually encloses to form the neural tube Neural Plate Neural Groove Neural Crest (PNS) Neural Tube (CNS) Thus, Day 21 is very important for the developing CNS. Unfortunately, many women may not even realize they are pregnant. Failure of Neural Tube to Close • Anencephaly: – Cephalic end of neural tube does not close – Missing major portions of the brain, skull and scalp – Often born without a forebrain • Spina Bifida – Caudal neural tube does not close completely – Range of severity and incapacitation varies greatly depending on level affected (rostralcaudal) – Incidence can be decreased by 70% with preconception and early pregnancy folic acid supplementation Neurodevelopmental Processes • Proliferation: Cell “birth”; first year; 10-12 • Migration: Journey to “job sites” • Differentiation: Specialization • Myelination: Facilitating communication • Synaptogenesis: Forming new synapses Differentiation = Specialization • Progenitor cells are “pleuripotent” – Can be induced to become any of a variety of adult cell types – Stem cell (debate) • CNS progenitors may become glial cells or neurons. Myelination continues for 2 decades! • Spinal Cord • Hindbrain • Midbrain • Forebrain Implications of Brain Development for The Death Penalty • Attitudes Toward Death Penalty? • What Age is Appropriate? – 16 Years Old? – 18 Years Old? – 21 Years Old? Can any single age be singled out as the correct one? Is Your Brain Done Yet? • http://www.npr.org/templates/story/story.php?storyId=1073624 • http://www.npr.org/templates/story/story.php?storyId=4518494 Synaptogensis continues throughout life, but… • Occurs more slowly in older people A B Plasticity: A Remarkable Story of Recovery • http://www.youtube.com/watch?v=TSu9HGnlM Brain Growth During the First Year is Quite Rapid • Birth: 350 grams • 1 Year: 1000 grams (2.2 pounds) • Adult: Roughly 1300 grams (~3 lbs) How Biological Sex Is Determined and What Can Go Awry Steroid-Mediated Anatomical Organization: The actions of T and DHT turn what would have developed into a clitoris, by default, into a penis. Sex Determination: “Messages in the Genes” • http://www.pbs.org/wgbh/nova/miracle/program.html Abnormal Sexual Phenotypes • Androgen Insensitivity Syndrome (AIS) – AKA “testicular feminization” – Appear female at birth – Gonads are undescended testes, not ovaries. – Normal female anatomical development during puberty because undeveloped testes never produce DHT – “Male” hypothalamus because brain defeminization is regulated by T Estrogen during in utero development Abnormal Sexual Phenotypes • 5-alpha-reductase insufficiency – T cannot be converted into DHT. – Genotypic and phenotypic male – Genitals are small due to inability to synthesize DHT. Abnormal Sexual Phenotypes • Congenital Adrenal Hyperplasia (CAH) – Genotype is XX – Overactive adrenal gland overproduces T – Vestigial penile development The Biology of Homosexuality • Evidence for a Homosexual gene? – Half of variance in homosexual preference associated with presence of “marker gene.” • Androgen levels – No differences in adulthood – During development??? • LH responding – Like females, homosexual males have a enhanced positive feedback response to exogenous LH than do heterosexual males. The Biology of Homosexuality • INAH-3 Dimorphism (LeVay studies) – Smaller in homosexual men than in heterosexual men, almost as small as in females. – HIV confound? • Anterior Commissure Dimorphism – AC is the main highway for inter-hemispheric communication. – Larger in homosexual men and in females than in heterosexual men. – Fashion implications? Psychological Development Key Theories of Personality and Cognitive Development Sigismund Freud • Psychosexual Theory of Development – Focuses is on instincts – Unconscious motivatations • Psychic (Mental) Energy Underlies: – Id: Instinctual nature of humans – Ego: rational and objective – Superego: internalized moral standards Freud’s Psychosexual Development • 5 stages • Conflicts between id, ego, superego – Id wants what it wants when it wants it – Ego learns to be more realistic – Superego ~ Morally acceptable behavior • Main Implication of Psychoanalytic Theory: – Early life experiences have long-term effects on personality. Critiquing Freud • Strengths – Emphasized the lasting importance of early life experiences in influencing who we become • Weaknesses – Testability? – It’s probably not all really just about sex! Erik Erikson • Most influential Neo-Freudian • Developmental Theory: Psychosocial Theory of Development • Differences with Freud – Less emphasis on libido/sex – More emphasis reasoning abilities – More adaptive view of human nature – Life-span implications Psychosocial Theory • Eight basic developmental stages • During each stage, a specific challenge must be mastered before the person can move on to the next stage. • “This–-or—that” setup Critiquing Erikson • Strengths – Emphasis on rational and adaptive nature of humans – Biological and social influences interact – Identified “identity crisis” (5th stage) which is still relevant. Critiquing Erikson • Weaknesses – Testability (again) – Describes how development proceeds better than it explains why it proceeds that way. Piaget: Cognitive Developmental Theory • Intelligence: The ability to adapt • An “Interactionist” Model – Nature and Nurture • At each new stage, children think in a qualitatively different way. Piaget’s Stages • Invariant sequence • Timing may differ on an individual basis • Stage determined by child’s reasoning processes, not her biological age. Stage 1: Sensorimotor Stage • Birth until the second birthday. • Getting to know the world through one’s senses and actions. • Infants “solve” problems with their actions, not with their minds. Object Permanence • Understanding that objects continue to exist even though they are no longer experienced. – Up through 4-8 months, “out of sight, out of mind”. – 8- to 12-month-olds frequently commit the “A-not-B error” • Search in “old” hiding place as if their behavior—not the object’s location– determines location. The A-not-B Error Infant’s egocentricism is so extreme that they believe that their behavior— and not the placement of the object— will determine where it’s found. Object Permanence (cont…) • By 1 year, child overcomes A-not-B • Still struggles with “invisible displacements” • Object permanence mastered by 18 months in most children Symbolic Capacity • Crowning achievement of sensorimotor stage • Mental symbols guide future behavior • Words enable more sophisticated problem solving. Stage 2: Preoperational Stage • Roughly 2 to 6 • Reasoning “hijacked” by most obvious features of the situation. – Easily fooled by appearances • Tests of Conservation Conservation • Conservation is the idea that certain properties of an object or substance do not change when its appearance is altered in some superficial manner. • Conservation-of-liquid-quantity task Error and Decentration • Decentration is the ability to consider two or more dimensions of a problem at once. – In fluid conservation, height and width must be considered simultaneously. • Preoperational thinking is characterized by centration • Child focuses on only the most apparent dimension, usually height. How is conservation attained? • Reversibility – Mentally “rewinding” and reconstructing what they just witnessed happening. – Requires a certain degree of maturation of memory “hardware” and “software.” Preoperational Egocentricism • Difficulty recognizing differences in perspectives (literally) – Preoperational children choose the perspective that corresponds to their own experience or reality • Assume that their desires (or dislikes) correspond to the desires (or dislikes) of others. – Do you and your friends want to go swimming or to the playground? Classification Difficulties • Goal: To sort objects based upon a specific criterion (e.g. sorting sticks by length) – Early preoperational children often change criteria moment to moment. – Older preoperationals group according to shape, color, function, et cetera Stage 3: Concrete Operational Stage • Learn to perform mental actions on objects – Corresponds to ~ 7 to 11 years of age – Child learns to add and subtract objects – Can classify dinosaurs, vehicles, clothes, etc. – Can arrange objects from largest to smallest Stage 3: Concrete Operational Stage • Improvements: • Conservation • Logic and deductive reasoning • Less egocentricism –Increased ability to “put themselves in others’ shoes.” Concrete Operational Conservation • Logic—not just appearances—serves as the child’s guide to understanding the task. • Logic is nascent at this stage, and restricted to concrete manipulations. Seriation and Transitivity • Task: Organize multiple objects along some dimension (e.g. sticks and length) – Preoperational: make one-to-one comparisons – Concrete operational: employ seriation to make multiple simultaneous comparisons – Transitivity (a corollary of seriation): • A > B > C. Ergo, A > C Stage 4: Formal Operational Stage • Age 11 or 12 and up • Child performs mental actions on ideas • Purely hypothetical scenarios Formal Operational Challenges • If you could put a third eye on your body, where would you put it and why? • Define justice. Critique of Piaget • Strengths – Research supported – Educational impact • Curriculum development – Parenting impact Critique of Piaget • Weaknesses – Ignores individual motivation • Development is not so passive – Stages are not universal – esp. last one • Formal operational (not everyone reaches) Autism: A Developmental Disorder • Appears during the first 3 years • Social interactions and communication skills are most significantly affected • Involves abnormal brain functioning – Smaller cerebellum, hippocampus, amygdala, caudate nucleus Verbal Skills Deficits • Difficulty in non-verbal and verbal interaction – Determining others’ emotions – Getting the “gist” – Focus on minutia and miss the “big picture” Prevalence of Autism • 1 in 166 births • Prevalence growing at a starling rate of 10-17% per year! • Autism knows no racial, ethnic, or social boundaries and is equally represented across SES levels. ...
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This note was uploaded on 03/22/2010 for the course PSYC 1101 taught by Professor Crystal during the Spring '08 term at University of Georgia Athens.

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