•Theory was advocated in early 1980s by Kugler, Kelso, and Turvey (among others). Following Bernstein’ theory in physiology
•Body systems spontaneously self-organize (not driven solely by CNS). And body structure guide toward movements (constraint to walk for Human)
•Body systems, performer’s environment, and task demands interact.
•Some systems may develop more slowly in the young or degrade faster in the old and thus control rate of development or change.
•Development is characterized by qualitative and discontinuous change.
•Change occurs across the life span.
Dynamic Systems (continued)
•Body does not develop at the same rate so each systems have rate limiter or controller that affect the movement.•Rate limiters are individual constraints that discourage motor skill until the system reach a critical level that allow the acquisition of the skill.
•Theory is based on the work of J.J. Gibson (1960s and 1970s)
.•Affordance is the function an environmental object provides to an individual.
–Characteristics define objects’ meanings.
–Object functions are based on individuals’ intrinsic dimensions (i.e., are body scaled) rather than object’s extrinsic, objective dimensions.
•Visual motion perception (Gibson JJ) helps to predict movement
•Body scaling: Example facing stairs
–A crawling infant: What the F… are the huge things
–Toddler: one step
–Adult; alternate step
–Arthritic elder: alternate footstep difficult so one step at a time
Growth and Aging Change Individual Constraints
•Genetic and extrinsic factors combine to influence growth and aging.
•We observe patterns in growth and aging
.–Universality: patterns that hold for all humans
–Specificity: individual variation
•Educators and therapists can make tasks developmentally appropriate.
•Early development is controlled by genes.
–Inherited abnormal development
•The embryo or fetus is sensitive to extrinsic factors.
•Conception to 8 weeks
•Differentiation of cells to form specific tissues and organs
•Limbs formed at 4 weeks
•Human form noticeable at 8 weeks
•8 weeks to birth
•Continued growth by hyperplasia (cell number) and hypertrophy (cell size)
•Cephalocaudal (head to toe) and proximodistal (near to far)
•Plasticity (capability of taking on a new function)
Fetal Nourishment structure
•The placenta: an interface between mother and fetus
•Multiple villi: increase of the surface of exchange
Fetal Nourishment what goes through
•Oxygen and nutrients diffuse between fetal and maternal blood in placenta.
• Poor maternal health status can affect fetus as the fetus may receive toxic or teratogenic substances.
Abnormal Prenatal Development
•Source of abnormal development can be genetic or extrinsic.
•Congenital defects (present at birth) can derive from genetic or extrinsic source.
Genetic Causes of Abnormal Development
•Can be dominant disorders (defective gene from one parent) or recessive disorders (defective gene from each parent)
.•Can result from mutation of a gene.
•Effects on growth and maturation are variable.
Extrinsic Causes of Abnormal Development
•Extrinsic factors can affect fetus through nourishment or physical environment.
•Teratogens delivered through nourishment system act as malformation-producing agents.
•Some teratogenic effects result from too much of a substance, some from too little.
•Placenta screens some substances (e.g., large viruses) but not all harmful ones.
•Harmful environmental factors include pressure, temperature, X and gamma rays, oxygen-deficient atmospheres, pollutants.
•Tissues undergoing rapid development at time of exposure are most vulnerable
Extrinsic causes of abnormal development
–Frequency of Down syndrome if mother age more than 40
– Regular, moderate exercise is related toincreased birth weight.
•Each hormone may have a critical role in development at specific phases in life span.
•Insulin plays indirect role, is vital for carbohydrate metabolism.
•Growth hormone is secreted by anterior pituitary gland. Under the control of somatotrophic hormones
•It is necessary for normal growth.
–Direct effects: growth hormone binds to its receptor on target cells. Adipocytes`: break down triglyceride
–Role in anabolism: stimulation of Fat, Protein and carbohydrate metabolism–Indirect: action on the Liver which is induces the release
• Insulin-like-growth factor1:
Stimulates the proliferation of chondrocytes
Stimulates the proliferation of myoblasts
•Deficiency can result in growth abnormality.
•Modulation of GH release by exercise, sleep, stress, nutrition
•But mainly secreted under the control of:
•hormone from the stomach
•These are secreted by thyroid gland.
•Triiodothyronine (T3) and thyroxine (T4)
•Synthesis stimulated by TSH produced by the axis pituitary gland and hypothalamus
•They influence whole-body growth.
•One plays a role in skeletal growth.
•Need T3 in order to develop brain structures
•Need of T3 from the mother during prenatal development (production starts at 20weeks)
•Thyroid Hormones play a role in neuromediator efficiency. Potentiate the effect of serotonin and acetylcholine
•PathologyHashimoto's Thyroiditis (hypothyroidism
:Fine Motor Movement Problems - Coordination of arms, hands, fingers.
Hypo or hyperthyroidism
Fine Motor Movement Problems - Coordination of arms, hands, fingers.
•Influence on growth, sexual maturation (sex organs, secondary sex characteristics)
–Secreted by testes (boys), adrenal glands (boys, girls).
–Hasten epiphyseal growth plate closure.
–Promote growth of muscle mass.
–Secreted by ovaries (girls), adrenal cortex (girls, boys).
–Hastens epiphyseal growth plate closure.
–Promotes accumulation of fat.
Endocrine System in Older Adults
•Imbalances may develop between nervous, endocrine, and immune systems.
•Thyroid disorders are more prevalent.
•Decreasing gonadal hormone levels are associated with loss of bone and muscle tissue.
Genes direct its development. 84% of all genes are expressed somewhere in the human brain
•Extrinsic factors exert influence, especially in the formation of synaptic connections. Variability and extrinsic factor can influence.
The nervous system...especially post natal is driven by genesYou have a good basis then you need to model it
Prenatal Neural Development
Process generally includes neuron formation, differentiation into general type, and migration.
Other cell types (glia) are of importance:
Different shaded cells have different morphology they are also polorizedThey have big nuclei and have paraya...axon-specialized to conduct imputs(proecess info)synaps connect to muscles or other things..myelin is an important fat...insulates axon and for sytatolic action
glia1)provide nutrients2)3)defend nervous cells4)insulate the axon...we have two systems, one is central and peripheral made of schwann cells
Prenatal Neural Development
•Once in place, neurons develop an axon to carry signals to neurons, glands, organs, muscles.
•Teratogens might disturb normal migration and branching. Broad spectrum of foetal alcohol syndrome–Ex: Alcohol and migration of Purkinje cells in cerebellum
First carry axonthen extand the axon to get the info..the fatal alcohol syndrom is desterbance of the neuron.. so the system does not work properly b/c the axons dont migrate properly
Early Neural Development
•Late in prenatal period, neurons start to fire electrical impulses (first at random, then forming circuits).
•Experience might play role in synaptic proliferation (strengthening some connections, weakening others).
•Neural network becomes more efficient with experience.
The neurons connects to make a synaptsAt first it seems like the neurons want to connect to everything..so you start to get rid of the synaps you create.Synergenic energy happends to the elimination of synaps
Give impulse to make sure they are ready to fire.. they start to for a circultry to make sure they can walk
At first you have less cells mainly neural cellsthen after the neural cell are made thats when u start makeing glia cells to support the nourishments
Postnatal Neurological Growth
•Brain growth increases rapidly after birth
•Growth involves these factors:
–Increases in size of neurons
–Prolific branching to form synapses
–Increases in glial cells for support and nourishment of neurons
–Increases in myelin to insulate axons
Stimulation of learning increases number of synaptic connections.
•The majority of brain synapses or connections form by age 3, and 85% of a child’s brain development is completed by age 5
Waves of development
•Development of synapse correlated with hormones.
When increasing the size of the cells in the brain it increases the amount of synapse
overproduction of dopimine
Motor Neuron Structure
The alpha motor neuron: Motor neuron connecting to muscle
Found in spinal cord and that what innervates are muscle.connects nervous system and muscle
Brain structures involved in Motor control.
Brain stem is important for all the autonomic systems
Frontal system develops very late, it is the one that does all the movement planning..control the motor system
•Extrapyramidal: Indirect pass through filters (cerebellum, basal ganglia…)
If you have a problem in your cerebellum you have problem its the fine tuning.. like if a patient wants to touch hi nose he will have trouble fine tuning the placement
•Spinal cord and lower brain centers are relatively advanced at birth.
•Their function is correlated with survival reflexes ( primitive period of Clark)
mylenated axons..mylein is kind of fat thats why its white
Cerebral cortex gradually becomes more functional after birth.
•Development of brain cortex: The pattern of human evolutionary expansion is remarkably similar to the pattern of human postnatal expansion
•Myelination of axons allows faster conduction of neural impulses.
•Direction of myelination tends to follow direction of conduction
mportant for the motor development of movement If you stike the mylenation..can cause damage*the direction of mylenation goes in same direction as conductions..You will promote schwann cell mylenation... some type of exercise promotes mylenation
Nervous System in Older Adults
•Aging involves loss of neurons, dendrites, synapses, neurotransmitters, and myelin.
•One theory of aging suggests that breaks in neural network links cause detours and therefore slowing.
•Exercise promotes improved cognitive function.
You also have many intermidiates to get to it.. which makes things much slower
You can release neural transmitter but the receptor might be the problemmulitplescoloris; often see motor developement One of the theories is that you can use you synaps nand neurons...the plastity of your system will help you innervated you..because you need to stimulate it and have the "muscle memory" i guess..
sensory neuronit has lots of receptors especially in the joint...proprioceptionIt fine tunes movement
Development and Aging of Body Systems: Summary
•Systems interact as they develop and age.
•During periods of rapid change, a system might be more sensitive to extrinsic factors
•Extrinsic factors play a greater role (genetic factors lesser role) as one moves through life.
•Model of constraints shows that a system can act as rate limiter (during growth) or as accelerator (of aging).
As you age you are more susceptible to extrinsic factors...at the beginning its more genetics