Physiological Influences on Development

1. Physiological Influences on Development EDFD127 Week 6 Reading: Stanley, F. (2003). The Real Brain Drain- Why putting children first is important for Australia.

2. Lecture Outline • Review • What is Physiology? • Physiology, Learning & Development- the basics • Physiology, Learning & Development- beyond the basics • Environmental influences on physiological development • Genetic influences on physiological development • Recent advances in our understanding of physiological development- cognitive sciences and neuroscience

3. Review Society and Culture as a Context for Development Education and Schools as a Context for Development Families as a Context for Development Physiology as a context for learning and development

4. Physiology • the internal workings of living things • the way an organism works, lives or keeps going • Concerned with: • Metabolism (our internal engine)- hormones and other chemicals • Organs and body systems (immune system) Enables growth, development and learning

5. Physiology, Learning & DevelopmentThe Basics • Physiological needs- food, water, shelter, • Physiological structure and function • Beneficial • super efficient gas exchange in the lungs • high percentage of fast-twitch muscle fibres • super fast conduction time in neurones • Detrimental • metabolic disorders, genetic disorders sleep

6. Basic Physiological NeedsNutrition • Appropriate nutrition is essential for rapidly growing babies. • Breast milk and infant formulas are especially suited to meet their needs. • Malnutrition during the early years can result in permanent stunting of physical growth and impairment of brain development. • Improved nutrition  earlier onset of puberty (Berk, 2003)

7. Basic Physiological NeedsSleep “…just as nutritional status, ambient temperature, level of stress, blood oxygenation, and other variables clearly affect the ability to learn, adequate sleep is vital for optimal performance in learning tasks.” (Siegel, 2001) • Sleep is essential for rapidly developing teenagers. • Teenagers need as much or more sleep than children- 9 ¼ hours per night.

8. Many teens are sleep-deprived. • feel despondent • don’t learn effectively; get poor marks • experience drowsiness in the early morning and mid-afternoon • have accidents etc • Because of their deep concern about these issues, sleep researchers are pushing for later school start times for teenagers. (Carskadon,1999) .

9. Physiology, Learning & DevelopmentBeyond The Basics • Getting down to the nitty gritty • Nerves; neurones; neurotransmitters • Chemicals- hormones; enzymes; body fluids (blood etc) • Genes

10. Big Names in History • Pavlov (1849-1936) • “nervism”-the nervous system (brain and peripheral nerves) controls our behaviour • reflexes- stimulus and response • conditioning- cortex involved • Watson (1878-1958); Skinner (1904-1990) • Behaviourism • learning through reinforcement

11. Cognitive Science- 1950’s • The technological age • Computers- thought processes could be modelled and therefore studied in a scientific manner • Educational Psychology • Cognitive load theory • Memory- 7 +/-3 rule

12. Modern times • Pathology- hormones; neurotransmitters • Stress hormones and learning (Yerkes Dodson curve) • Neurophysiology- CT; MRI; PET scans • Mathematical thinking (Geek, 2003) • Genetics and epigenetics • Bridging these areas • Relationship between psychological and physiological health

13. Psychological Health Determines Physical Health • Basic psychological needs • competence, autonomy, relatedness (SDT- Ryan and Deci) • love, friendship, achievement, joy… • Relationship- love and affection • Harlow’s classic monkey experiment (Harlow & Zimmerman, 1959) • Meaney’s rat studies (Liu D. et al. 1997) • Romanian orphans (Kaler & Freeman, 2006)

14. Harlow’s Monkey Experiments • Baby rhesus monkeys given a choice between two surrogate mothers, one made from a soft material, similar to a parent monkey, and the other was made from wire mesh and had a bottle attached to it. • The monkeys spent most their time with the clothed monkey rather than the one with offers food. http://rahuldesign.files.wordpress.com/2008/12/harlow-monkey.jpg

15. Meaney’s Research • The equivalent of child neglect in rats is restricted licking and grooming behaviour, restricted vocalising and not nursing in an arched back posture. • Neglected rat pups are less adventurous, don’t learn as quickly, are highly stress reactive, exhibit abnormal socialisingbehaviours and are physically smaller and sicker than their nurtured counterparts. • In adulthood these rats continue to have problems relating to other rats, are fearful, stress reactive and anxious and become neglectful mothers themselves. • Young monkeys taken from their mothers show similar developmental abnormalities related to physical, cognitive and social/psychological development.

16. Both the rats and monkeys show: • chronic elevation of stress hormones • abnormalities in their brain structure- smaller brains overall, small hippocampuses, small amygdala, smaller frontal and prefrontal lobes( important for memory, emotion and impulse control, and long term planning) • An environmental insult (social and psychological neglect) causes changes to both physiology and anatomy.

17. Chronic Stress in Young Children • Chronic elevation of stress hormones in childhood predicts: • High stress reactivity in adulthood • Brain abnormalities • Impaired memory, learning problems emotional and behaviouralproblems problems with impulse control • Anxiety and depression • Decreased growth hormone (De Bellis 1999, 2001, 2002)

18. Physiology and Environment • The family- family functioning (stress, abuse); maternal health and nutrition; health of siblings • Socioeconomic status- poverty, homelessness • Cultural background- indigenous peoples • Surrounds- environmental toxins (radiation, agent orange); access to clean waterand facilities • Prenatal exposure to teratogens- drugs, smoking, alcohol, radiation, environmental pollution, maternal disease, inadequate nutrition, maternal stress • Birth complications- oxygen deprivation, prematurity • Society and culture- public policy

19. Children from families where conflict between members is the norm and those who are abused or neglected do not cope well. They have chronically high levels of stress hormones. • Child neglect and child abuse are chronic societal problems. There has been more than a doubling in the number of reports of suspected child neglect and and abuse in Australia over the past 12 yrs.

20. Social Gradient • “The differences in a particular characteristic across the social strata from the most to the least advantaged.” • If there is a difference, then a gradient can be said to exist and we say that there is a disparity. • e.g there is a large disparity for low birth weight whereas there is virtually no disparity for childhood cancers • The ‘paradox of progress’- the differences between the ‘haves’ and the ‘have nots’ have increased despite increases in wealth and living conditions. (Stanley 2003, p4)

21. Prevalence of overweight/obesity, 7-15 yr olds: 1985 2003 Males 9.3% 23.1% Females 10.6% 30.5%

22. Health determinants • Exercise • Diet • Social support • Other • Smoking • Sleep • Education • Economic status • Environment (Marmot 1998; Harvard Health 2000; Kahneman, 2004)  1/3

23. What about the other 2/3? “the control factor” “control over our destiny” (Marmot, 1998) Without control we experience stress

24. The Psychobiological Stress Response (Brunner and Marmot 2006, p27) Stress Hormones Brain Immune System Insulin Cortisol Neurotransmitters Metabolic Immunoglobulins White cells Heart Lungs Kidney Gut motility Fat metabolism

25. Stress is all about Balance Stressors • Family conflict • Peer/school conflict • Poor coping strategies • Early deprivation Coping Resources Physical health Helpful Coping strategies Social resources Personality/Genetics RESILIENCE

26. Stress and coping • “Stress is a challenge to the systems of the body such that we are no longer in control.” • “Coping is the capacity to survive the immediate stress and then to return to a state of control.” McEwan, B. S. 1998. Protective and damaging effects of stress mediators. New England Journal of Medicine 338, 171-179.

27. Poor coping • If we do not cope well we have sustained increases in stress hormones (adrenaline and cortisol). • When these hormones remain elevated they cause damage to the body.

28. Psychological wellness is essential for healthy physical and neurological development.

29. Critical Periods • Variable effects of influences on development depending on time of exposure • Pre-natal- body temp. of mother in first 2 months of pregnancy; folate • Post-natal- affection; congenital cataracts; language acquisition in deaf children • Early childhood- Extreme emotional deprivation can interfere with the production of growth hormone, thereby stunting children's growth. • More the exception than the rule, especially in terms of learning. Has to be dire circumstances. ‘Good enough’ approach.

30. Physiology and Nature:Genes and Heredity • Gene expression determines the characteristics that make us human and contribute to individual differences in appearance and behavior. • Heredity affects physical growth by regulating the production and effect of hormones. • There are wide variations in normal development e.g. typical age range for walking is 10-13 months but there are some children who walk at 8 months and some who walk at 18 months.

31. Genetic Disorders • Inheritance of harmful genes can cause developmental problems (Cystic Fibrosis, Fragile-X Syndrome). • Chromosomal abnormalities can cause developmental problems (Down’s Syndrome). • Genetic counseling and prenatal diagnosis help people at risk for transmitting genetic disorders.

32. Genotype • The pattern of genes a person inherits; a person’s inborn capacity or potential • Phenotype • Traits a person displays resulting from the interplay of genes and environment

33. Chromsomes Chromosomes • In the nucleus of cells • Store and transmit genetic information • Each cell in the human body contains 23 pairs • 22 pairs of autosomes + 1 pair of sex chromosomes http://www.accessexcellence.org/AE/AEPC/NIH/images/chromosome.gif

34. DNA: Deoxyribonucleic Acid • Chromosomes are made up of DNA • Segments of DNA are called ‘genes’ • Feb 2001- 30,000 genes • Genes code for proteins • Proteins make our muscles, skin etc and also enzymes and neurotransmitters etc

35. http://creationwiki.org/pool/images/thumb/5/54/Chromosome.png/450px-Chromosome.pnghttp://creationwiki.org/pool/images/thumb/5/54/Chromosome.png/450px-Chromosome.png

36. Patterns of Genetic Inheritance • Two forms of a gene occur at the same place on the autosomes, one from the mother and one from the father. • Homozygous- 2 copies of the same gene • i.e. AA or aa • Heterozygous- 2 different forms of the gene • i.e. Aa

37. Patterns of Genetic Inheritance • Genes can be ‘dominant’ or ‘recessive’ or ‘co-dominant’ • AA- 2 dominant genes = homozygous dominant • Aa- 1 dominant + 1 recessive = heterozygous • aa- 2 recessive genes = homozygous recessive • In a heterozygote, the dominant gene is expressed • A heterozygous individual can pass on a recessive gene or a dominant gene.

39. AA + Aa AA Aa AA Aa

40. Aa + Aa AA AaAaaa

41. Sex Chromosomes • 2 sex chromosomes- X and Y • XX- female • XY- male • X chromosome longer than Y chromosome- more genes on the X

42. X-Linked Inheritance • For some genes, males only have 1 copy on X chromosome…no corresponding gene on the Y chromosome • If X chromosome gene is faulty in a male, no corresponding gene to counteract and take over • If X chromosome gene is faulty in a female, corresponding gene on other X chromosome can take over • X-linked inheritance- colour blindness, baldness, haemophilia, Duchenne Muscular Dystrophy

43. Other forms of Inheritance • Many traits or characteristics are polygenic- influenced by a number of genes, e.g. behaviour, cognitive processes, ?ADHD • Some traits are said to have variable penetrance- do not follow classical dominant or recessive inheritance patterns, e.g. Fragile X syndrome.

44. Physiology is influenced by Genes + Environment • Nature via nurture (Matt Ridley, 2003) • Diet, heart disease and cholesterol genes • Childhood abuse and stress gene • Marijuana use and genetic predisposition to psychosis (Caspi et al., 2005) • Depression gene- individuals with one or two short alleles of the 5-HTT serotonin transporter gene become depressed more often after stressful events than individuals with two long alleles of this gene (Caspi, et. al., 2003)