Infancy Physical Development Physical Growth and Development OT

Infancy: Physical Development Physical Growth and Development OT 500 Spring 2016

What Are the Sequences of Physical Development? � Cephalocaudal Development ◦ Upper part of the head to the lower parts of the body � Proximodistal Development ◦ Trunk outward – from body’s central axis toward periphery � Differentiation ◦ Tendency of behavior to become more specific and distinct

What Patterns of Growth Occur in Infancy? �Weight doubles at about 5 months; triples by first birthday �Height increase by 50% in first year �Infants grow 4 to 6 inches in second year; and gain 4 to 7 pounds �Growth for the most part appears continuous but actually it occurs in spurts

One week

6 weeks

2 months

3 months

4 Months

5 Months

6 months

7 months

8 Months

9 months

Growth Curves for Weight and Height Figure 5. 1

Changes in Body Proportions � Children’s heads are proportionately larger than adults’ ◦ Cephalocaudal development � Changes in proportion of arms and legs

What Is Failure to Thrive? � Growth impairment during infancy and early childhood � Causes may be organic or non-organic � Biologically based or non-biologically based ◦ Marasmus; Condition related to FTT; Diet low in essential nutrition � Linked to physical, cognitive, behavioral, and emotional problems � Deficiencies in caregiver-child interaction may play a role � Canalization – catch up growth once FTT is resolved

What Are the Nutritional Needs of Children? � Infants require breast milk or iron fortified formula � Solid foods may be introduced about 4 to 6 months ◦ Iron-enriched cereal, strained fruits, vegetables, and meats � Whole cow’s milk delayed until 9 to 12 months ◦ Teething biscuits in later part of first year

Why Do Women Bottle-feed or Breastfeed their Children? � � � Choice to breastfeed is influenced by ◦ Domestic and occupational arrangements ◦ Attitudes regarding benefits for bonding and infant health ◦ Fear of pain, unease with breastfeeding, and public breastfeeding ◦ Community and familial support; Level of education Colostrum early form of breast milk Advantages of breast milk ◦ Conforms to digestion process, possesses needed nutrients with a ◦ ◦ ◦ high level of nutrients into low volume Contains mother’s antibodies; Protects against childhood lymphoma Helps protect against infant diarrhea; Is less likely than formula to cause allergies Helps prevent obesity later in life Maternal health benefits Human newborns prefer it; It’s free

What Are the Disadvantages of Breast Milk? � Disadvantages of breast milk ◦ HIV, alcohol, drugs, and environmental hazards may be transmitted through breast milk ◦ Mother must be adequately nourished ◦ Physical demands on mother � Lack of social support � Return to work – pumping can be too demanding � Stress and mastitis � What about mothers who smoke? ◦ No harmful effects on infants have been noted ◦ Can reduce milk supply

Development of the Brain and Nervous System

Neurons (contain cell body, dendrites, axon; the axon is coated with myelin) � Neurons are the basic unit of nervous system; they receive and transmit messages; formation of neurons is complete at birth � Neurons vary according to function and location; As child matures, neuronal axons grow in length, Dendrites and Axon terminals proliferate so that connections or networks become more complex � Myelin makes messages more efficient; myelination occurs with maturation through childhood; Inhibition of myelination results in disease such as multiple sclerosis

Anatomy of a Neuron Figure 5. 3

Brain Development � The brain is the command center of organisms � Brain of neonate weighs less than one pound; By the child’s first birthday, the brain triples in weight, reaching nearly 70% of adult weight � Brain Structures include the ◦ Medulla : heartbeat, respiration ◦ Cerebellum: Maintains balance, control motor behavior, coordinate eye movements with body sensations ◦ Cerebrum: Allows human learning, thought, memory, language

Growth of Body Systems as a Percentage of Total Postnatal Growth Figure 5. 4

Structures of the Brain Figure 5. 5

How Does the Brain Develop? � Growth Spurts in Brain Development ◦ Prenatal - during 4 th and 5 th months �Proliferation of neurons ◦ 25 th week prenatal through end of second year after birth �Proliferation of dendrites and axon terminals

Increases in Neural Connections in the Brain Figure 5. 6

Brain Development in Infancy � At birth, brain areas well myelinated include ◦ Heartbeat and respiration ◦ Sleeping and arousal ◦ Reflex activity � Intentional physical activity coincides with myelination � Myelination of sensory areas ◦ Hearing – begins about 6 th month of pregnancy and continues to age 4 ◦ Vision – begins shortly before full term but develops rapidly

How Do Nature and Nurture Affect the Development of the Brain? � Brain development is affected by maturation (nature) and sensory stimulation and motor activity (nurture) ◦ Rats in enriched environment �More synapses per neuron ◦ Human infants have more neural connections than adults �If activated by experience, connection survives �If not activated, connection does not survive ◦ Adequate nutrition is necessary

Motor Development

Motor Development in Infancy � � � Follows cephalocaudal and proximo-distal patterns Develop postural control , balance and stability; further development of the musculoskeletal system Many infant motor primitive reflex patterns are “Integrated”; replaced by higher level, voluntary controlled movements; Develop automatic reactions like righting, equilibrium, and protective reactions Gross motor skills develop; coordination, muscle strength, endurance, and agility; Fine motor skills including reaching and grasping, hand use, dexterity, visual- motor coordination, bilateral coordination MAJOR MOTOR MILESTONES: �Rolling over supine to prone, 3 -4 months �Rolling over prone to supine 4 -6 months �Sits up 5 -7 months; Belly crawls 5 -7 months �Crawls on hands and knees 7 -9 months �Pulls to stands and cruises holding onto something 9 -11 months �Walks 10 -14 months

Control of the Hands; Fine Motor Skills Newborns track objects with eyes but do not reach for them � Grasp reflex (dominates until about 3 rd month) � ◦ Grasp but do not release intentionally � Voluntary grasping about 3 months ◦ Ulnar grasp, then radial grasp; gross fisted grasp patterns ◦ Pincer grasp with thumb opposition around 9 -13 months ◦ Able to transfer toys from one hand to the other around 4 -6 months ◦ Voluntary release with some control around 10 -14 months; can stack 2 one inch block around 15 months � Visual – motor coordination developing; copy simple horizontal and vertical lines 2 -2. 5 years of age

Pincer Grasp Figure 5. 7

Other gross motor skills ◦ Walk backwards ◦ Run ◦ Kick a ball ◦ Jump (clearing both feet together) ◦ Jump down from a raised surface ◦ Catch a large ball ◦ Move a push riding toy ◦ Climb up stairs; Climb down stairs ◦ Ride/Pedal a trike ◦ Climb in and out crib ◦ Climb into a car seat

Motor Development in Infancy Figure 5. 8

Creeping Figure 5. 9

Walking Figure 5. 10

What Are the Roles of Nature and Nurture in Motor Development? � Maturation (nature) ◦ Myelination and differentiation is needed for certain voluntary motor activities � Experience (nurture) ◦ Experimentation to achieve milestones ◦ Slight effect in training to accelerate motor skills � Reaction range ◦ Limits for the expression of inherited traits

Native American Hopi Infant Strapped to a Cradle Board Figure 5. 11

Sensory and Perceptual Development

Development of Visual Acuity and Peripheral Vision � Neonates are nearsighted ◦ Greatest gains in visual acuity between birth and 6 months ◦ By about 3 to 5 years of age, approximate adult levels � Neonates have poor peripheral vision ◦ Perceive stimuli within 30 degree angle ◦ By 7 weeks increases to 45 degrees ◦ By 6 months of age, equal to adult (90 degrees)

What Captures the Attention of Infants? How Do Visual Preferences Develop? � Neonates attend longer to stripes than blobs ◦ By 8 to 12 weeks, prefer curved lines over straight � Infants prefer faces ◦ Discriminate maternal and stranger faces ◦ Prefer attractive faces ◦ Pay most attention to edges ◦ Depth Perception: Develops around 6 months (onset of crawling) Research using the Visual Cliff; Gibson and Walk (1960) show infants will not go off the deep end!

The Development of Perceptual Constancies? (Size, shape) � � � Perceptual constancy – perception of object remains stable although sensations may differ under various conditions Size constancy – perception of object’s size remains stable although retinal size may differ due to distance; abilty documented in early infancy Shape constancy – perception of object’s shape remains stable although shape on retina may change due to looking at objects from various perspectives; ability seen as early as 4 -5 months of age.

How Does the Sense of Hearing Develop in Infancy? � Neonates can orient toward direction of a sound ◦ 18 months locate sounds as well as adults � � Infants exposed to moderate noise levels as background habituate to it and are less likely to waken due to noise By 1 month, infants perceive differences between similar speech sounds By 3½ months discriminate caregivers’ voices Infants perceive most speech sounds present in world languages ◦ By 10 to 12 months, lose capacity to discriminate sounds not found in native language

Development of Coordination of the Senses � Infants recognize that objects experienced by one sense are the same as those experienced by another ◦ Looked longer at novel items than those previously handled

Do Children Play an Active or Passive Role in Perceptual Development? Role of Nature and Nurture � � Neonates’ role in perceptual development is largely passive early on Later, a child’s role in perception becomes more active as they gain some control over what they look at, where they go; start to develop interests and preferences so that their attention becomes selective, and irrelevant information ignored � � Some in-born ways of responding to sensory stimuli; may be some sensitive periods for vision Nature and nurture equally important in perceptual development