P HYSIOLOGICAL I NFLUENCES ON D EVELOPMENT EDFD127 Week 6 Reading: Stanley, F. (2003). The Real Brain Drain- Why putting children first is important for.

PHYSIOLOGICAL INFLUENCES ON DEVELOPMENTEDFD127 Week 6

Reading: Stanley, F. (2003). The Real Brain Drain- Why putting children first is

important for Australia.

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

REVIEW

Physiology as a context for learning and

development

Society and Culture as a Context for Development

Education and Schools as a Context for Development

Families as a Context for Development

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

PHYSIOLOGY, LEARNING & DEVELOPMENTTHE BASICS

Physiological needs- food, water, shelter,

Physiological structure and functionBeneficial

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

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)

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.

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)

.

PHYSIOLOGY, LEARNING & DEVELOPMENTBEYOND THE BASICS

Getting down to the nitty gritty

Nerves; neurones; neurotransmitters

Chemicals- hormones; enzymes; body fluids (blood etc)

Genes

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

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

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

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)

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

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 socialising behaviours 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.

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.

CHRONIC STRESS IN YOUNG CHILDREN Chronic elevation of stress hormones

in childhood predicts: High stress reactivity in adulthood Brain abnormalitiesImpaired memory, learning problems

emotional and behavioural problems problems with impulse control

Anxiety and depressionDecreased growth hormone

(De Bellis 1999, 2001, 2002)

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 water and 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

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.

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)

PREVALENCE OF OVERWEIGHT/OBESITY, 7-15 YR OLDS:

1985 2003 Males 9.3% 23.1%Females 10.6% 30.5%

HEALTH DETERMINANTS

ExerciseDietSocial supportOther

SmokingSleep Education Economic status Environment

(Marmot 1998; Harvard Health 2000; Kahneman, 2004)

1/3

WHAT ABOUT THE OTHER 2/3?

“the control factor”

“control over our destiny”(Marmot, 1998)

Without control we experience stress

Stress

Immune SystemMetabolic

HormonesBrainInsulinCortisol

NeurotransmittersHeartLungsKidney

Gut motilityFat metabolism

ImmunoglobulinsWhite cells

THE PSYCHOBIOLOGICAL STRESS RESPONSE (BRUNNER AND MARMOT 2006, P27)

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

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.

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.

Psychological wellness is essential for healthy physical

and neurological development.

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.

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.

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.

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

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

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

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

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

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.

Dominant Recessive

Dark Hair Blonde hair

Curly hair Straight hair

Normal hearing

Facial dimples No dimples

Normal vision Nearsightedness

Farsightedness Normal vision

Normal vision Congenital cataracts

Double jointedness Normal hair

Blood Type A Blood Type O

AA + Aa

AA Aa AA Aa

Aa + Aa

AA Aa Aa aa

SEX CHROMOSOMES

2 sex chromosomes- X and Y XX- female XY- male

X chromosome longer than Y chromosome- more genes on the X

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

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.

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)