Infant Brain Development 1

8/4/2019 Infant Brain Development 1

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Infant Brain Development The Unfinished Brain



The Infinite Array� The brain and nervous system contain

billions of interconnected neurons.

� Neurons form trillions of connectionsand the pathways.

� The number and organization of these

connections influence everything, fromthe ability to recognize letters to the

maintenance of relationships.



Making Connections� Neurons develop rapidly before birth.

� At birth, infants have all, or most, of the brain cellsthey will ever have.

� Connections or "wiring" between these cells isincomplete - connections have to be built.

� Between birth and 8 months synapses form rapidly.

One neuron can connect with 15,000 other neurons.

� In the first 3 months of life, the synapses multiplymore than 20 times.

� At 3 months, the baby has more than 1,000 trillionsynapses.



Brain Plasticity in Early Childhood� Connections are made permanent from early

infancy to early childhood

� As we mature, the brain physically changesdue to outside experiences.

� The first three years see the most rapidchanges due to the bombardment of experience (everything is new!).

� At this time, the brain is most flexible andprepared to learn. (plasticity)



Pruning� Connections that are not used are

removed by "pruning"

� After the first birthday, pruning occurs

more quickly.� A 3-year-old child has twice as many

connections as an adult.

� By 10 years, a child has nearly 500trillion synapses, which is the same asthe average adult.



Experience Builds Connections Early childhood experiences physically

determine how the brain is "wired."

Early sensory experiences create newsynapses.

Repetition of experiences strengthen them.

The number of connections can go up ordown by 25 % or more, depending on theenrichment of the environment.

Those synapses that aren't used are pruned.



Window of Opportunity

At about age 10, the brain begins to dramaticallyprune extra connections and make order of thetangled circuitry of the brain.

� Pruning occurs for about 12 years but the brainmaintains flexibility for future learning

New synapses grow throughout life

Adults continue to learn, but they do not master

new skills so quickly

� Learning language is an example of this principle.



Language Acquisition

� At 3 months the brain has the potential todistinguish several hundred spoken sounds.

� Over the next few months the brain organizesitself to recognize only the sounds it hears.

� During early childhood the brain retainsplasticity for this information ± The ability to discriminate sounds it has discarded

� After age ten, this plasticity is lost

� This is why young children can easily learnforeign languages accent-free. ± Older children & adults can still learn language,

but more effort is required.



Genetics & Environment Interact � There is mounting evidence that early

experiences can dramatically alter the

way genes are expressed in thedeveloping brain.



Sensory Stimulation� Touch, sound, sight, taste, smell, all build

connections .

Some researchers, believe "the number of words an infant hears each day is the singlemost important predictor of later intelligence,school success, and social competence."

� Touch also is key to brain development

± Research on infant massage suggests that inpreemies, massage causes faster growth anddevelopment.



Security

� The most fundamental task of an infant is to learnhow to meet his needs

� If adults respond predictably to his cries and providefor his needs, the infant feels secure.

± He then focuses his attention on exploring, allowing hisbrain to develop.

� If his needs are met only sporadically, the infant willfocus his energies on meeting his needs.

± He will have more and more difficulty interacting withpeople and objects in his environment

± His brain will shut out the stimulation it needs to develophealthy cognitive and social skills.



Deprivation

� Infants in environmentally deprived facilitieshave brains smaller than those of children whogrow up in sensually rich environments

� Studies of over 1,000 abused and neglectedchildren found that children who were rarelytouched or spoken to had brains 20-30%smaller than most children their age.

� In some cases the brains of children from

deprived environments resemble the brains of Alzheimer's patients.

� Animals raised in zoos have brains that are 20-30% smaller than animals raised in the wild.



Trauma

� Childhood trauma can directly affect the waythe brain functions.

� Traumatized children continue to showphysical symptoms of fear even in the

absence of threatening stimuli ± have high resting heart rates, high levels of stress

hormones in their blood, and problems sleepingsuggests that their brains are in a permanent stateof "high alert".

� These children tend to develop emotional,behavioral and learning problems.



The Role of Cortisol

� Studies examined the effect of the stresshormone, cortisol, on brain development.

� Amount of cortisol in the body can bemeasured in the saliva allowing testing oninfants & children.

� If levels of cortisol are high, the heart rate,digestive system and ability to think are

affected.� At birth, the human adrenocortical system

is highly responsive to stimulation.



Cortisol & Brain Development � The brain is the major target of cortisol.

� Frequent and prolonged exposure to elevated

cortisol may affect the development of brainareas involved in memory, negative

emotions, and attention regulation.

� High cortisol levels in preschool children

coincide with poor "effort control" and self-regulatory competencies.



Learning to Cope With Stress

� Research on neural plasticity demonstratesthat experience shapes the developing brain

� Early experiences affect later emotional,behavioral and hormonal stress reactivity.

� This is accomplished by preventingelevations in cortisol in reaction to threateningand mildly painful events.

� A sense of control is the key factor inmodulating cortisol response to potentiallythreatening o painful events. ± The presence of a trusted caregiver during stress

reduces the production of cortisol.



Sleep� There is a strong correlation between the

amount of sleep a child gets and normal braindevelopment.

� The brain needs a period of deep,uninterrupted, physiological rest

� Children between birth and age twelve whodo not receive enough sleep do poorly on

extended performance testing, creativity andhigher-level problem solving.

� May also relate to cortisol levels



The Basis of Learning The past decade has seen a massive

amount of research on infant brain

development & learning Babies know more than we once

thought



A Summary of Infant Skills

2-day-old infants recognize their mother's voiceand prefer it over other sounds.

3-month-olds can discriminate primary colors, &prefer red & yellow over blue & green.

6-month-olds recognize a mobile 2 weeks afterbeing exposed to it for 2, 15-min. intervals.

7-month-olds can match angry or happy facialexpressions with the corresponding vocalexpression.

9-month-olds will imitate simple actions whichthey see being performed on objects, one weeklater.



Formation of Memory Two types of memory: (Restak)

Wide sense" memory with acquired

knowledge. does not associate time or place

Strict sense memory

capable of association with time or place



Wide Sense Memory Wide sense' memory seems to be present

from birth.

Infant can learn, modify reactions, andexhibit surprise when something new occurs

We just know something

Might appear to be innate

Located in part of the brain that developsearly.



Conditioned Learning

Newborns can be taught via conditioning operant conditioning is one type of

associative learning in which there is a

contingency between the response andthe reinforcer.

"Place a pair of earphones on a newbornbaby and that baby will soon learn to suckin a pattern so as to hear her mother'svoice over the earphones . . .



True Memory Memory in the "strict sense" comes into

being with the development of higher

levels of the brain. The amygdala and frontal lobes are

important in memory

They develop relatively late in infancy,at about ten months of age.



Memory & Learning

Sound perception develops first and fastest

Researchsearch by Jusczyk et al. at JohnsHopkins investigated infants' long-term

memory for the sound patterns of words. This study shows that infants have apreviously unknown type of unconsciousmemory for detailed sound patterns

Even if infants don't understand what theyhear, "their nervous system is payingattention."



The Research

Researchers studied 8-month-old infants over the course of 10visits in 2 weeks.

They played them a half-hour audio tape of children's stories.

Two weeks after the last visit, the infants were brought to thelab.

Researchers read them lists of words, some of which camefrom the stories

Mixed in were foils that sounded similar but had not beenmentioned in the stories.

Story words kept the infants' attention about 15% longer thanthe foils, an indication that the infants remembered the story

words.

A control group of infants that had never heard the stories paidequal attention to words of either list.



Learning Language is Incremental

The same researchers found that infants first learn to distinguish sound patterns of theirnative languages.

This ability develops faster than any other

aspect of language. Infants listened longer to their own names

than to any other name, even the ones withsimilar sound patterns.



Infant Brain Makes Sense of Language

A French study found that 3-month-old babiesrespond to spoken sentences

Used functional magnetic resonance imaging(f MRI) visualize infants' reactions to speech.

Measured brain activity as they spoke "sense" and"nonsense" to the 2- and 3-month-olds.

The sense consisted of short French sentences;the nonsense of the same sentences, recorded

and played back in reverse. Earlier studies found infants just 4 days old could

distinguish between their native language and aforeign language.



The Language Spurt

At about 18 months there is a sudden dramaticincrease in word use

Vocabulary increases to about 100 words and quicklyexpands

This change, called the naming explosion orvocabulary spurt, is a key stage in development

Traditionally explained as the result of progressionsin conceptual development

Woodward et al at the University of Chicagoinvestigated this phenomenon

Showed that children comprehend words equally wellat 13 months, when they use just five to ten words



The Research

They exposed 13- and 18-month-old infants to

unfamiliar objects like a big plastic paper clip and aplastic strainer

Called one of them by a made-up name, toma.

One person repeated the word nine times in

different situations Another person, unaware which object was the

toma tested the child's comprehension through aplay activity

Presented two objects on a tray and asked the childto 'put the toma in the box.

Found little difference in rates of word learning andretention between the two groups of infants.



Categorizing Babies can also categorize words

A study from Johns Hopkins:

"New findings suggest that infants as youngas 9 months use words to begin shaping theirview of the world, arranging objects intomental categories, in a process previously

associated more with preschoolers than withmere babes."



Development of ReasoningSkills

Babies know more than we believe

Children begin to develop reasoning skills as

young as seven months of age. Study conducted at the University of Chicago on

seven-month-old babies to assess their reasoningskills

Used visual habituation to determine infant understanding of the actions of inanimate objects.

Measured their attention span to different events.



The ResearchStudy

The longer a baby watches, the more likely he istrying to understand something unexpected

The first test - babies watch a videotape of an

object that moves behind a screen blocking thebabies' view of the action.

Another object moves off the screen after thefirst object enters.

The second test - the screen is removed to showthe two objects colliding or not colliding beforethe second object moves.



Results

Babies watch longer when objects dont collide Researchers concluded that they are surprised

because it violates a principle they have learned: forobjects to cause other objects to move, they must

touch each other. If babies are surprised when humans move without

touching, that would indicate that they expect humansand objects to react to each other in the same way.

The findings support the conclusion that by sevenmonths, infants differentiate between people andobjects in their reasoning about simple causalsequences

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Infant Brain Development 1