Infant Brain Development

The Unfinished Brain

The Infinite Array

• The brain and nervous system contain billions of interconnected neurons.

• Neurons form trillions of connections and the pathways.

• The number and organization of these connections influence everything, from the 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 cells they will

ever have.• Connections or "wiring" between these cells is incomplete -

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 multiply more than

20 times. • At 3 months, the baby has more than 1,000 trillion

synapses.

Brain Plasticity in Early Childhood

• Connections are made permanent from early infancy to early childhood

• As we mature, the brain physically changes due to outside experiences.

• The first three years see the most rapid changes due to the bombardment of experience (everything is new!).

• At this time, the brain is most flexible and prepared 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 500

trillion synapses, which is the same as the average adult.

Experience Builds Connections

• Early childhood experiences physically determine how the brain is "wired."

• Early sensory experiences create new synapses.

• Repetition of experiences strengthen them.• The number of connections can go up or

down by 25 % or more, depending on the enrichment of the environment.

• Those synapses that aren't used are pruned.

Window of Opportunity

• At about age 10, the brain begins to dramatically prune extra connections and make order of the tangled circuitry of the brain.

• Pruning occurs for about 12 years but the brain maintains 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 to

distinguish several hundred spoken sounds.• Over the next few months the brain organizes

itself to recognize only the sounds it hears.• During early childhood the brain retains plasticity

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 learn

foreign 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 the developing 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 single most important predictor of later intelligence, school success, and social competence."

• Touch also is key to brain development– Research on infant massage suggests that in

preemies, massage causes faster growth and development.

Security• The most fundamental task of an infant is to learn

how to meet his needs• If adults respond predictably to his cries and provide

for his needs, the infant feels secure. – He then focuses his attention on exploring, allowing his

brain to develop.

• If his needs are met only sporadically, the infant will focus his energies on meeting his needs. – He will have more and more difficulty interacting with

people and objects in his environment – His brain will shut out the stimulation it needs to develop

healthy cognitive and social skills.

Deprivation

• Infants in environmentally deprived facilities have brains smaller than those of children who grow up in sensually rich environments

• Studies of over 1,000 abused and neglected children found that children who were rarely touched 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 way

the brain functions. • Traumatized children continue to show

physical 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 sleeping suggests that their brains are in a permanent state of "high alert".

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

The Role of Cortisol• Studies examined the effect of the stress

hormone, cortisol, on brain development.• Amount of cortisol in the body can be

measured in the saliva allowing testing on infants & 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 brain areas 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 demonstrates that

experience shapes the developing brain• Early experiences affect later emotional, behavioral

and hormonal stress reactivity.• This is accomplished by preventing elevations in

cortisol in reaction to threatening and mildly painful events.

• A sense of control is the key factor in modulating cortisol response to potentially threatening 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 brain development.

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

• Children between birth and age twelve who do not receive enough sleep do poorly on extended performance testing, creativity and higher-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

voice and 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 after

being exposed to it for 2, 15-min. intervals. • 7-month-olds can match angry or happy facial

expressions with the corresponding vocal expression.

• 9-month-olds will imitate simple actions which they see being performed on objects, one week later.

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, and exhibit surprise when something new occurs

• We just “know” something• Might appear to be innate• Located in part of the brain that

develops early.

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 and the reinforcer.

• "Place a pair of earphones on a newborn baby and that baby will soon learn to suck in a pattern so as to hear her mother's voice 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 & LearningSound perception develops first and fastest

• Researchsearch by Jusczyk et al. at Johns Hopkins investigated infants' long-term memory for the sound patterns of words.

• This study shows that infants have a previously unknown type of unconscious memory for detailed sound patterns

• Even if infants don't understand what they hear, "their nervous system is paying attention."

The Research• Researchers studied 8-month-old infants over the course of

10 visits 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

the lab. • Researchers read them lists of words, some of which came

from the stories • Mixed in were foils that sounded similar but had not been

mentioned in the stories. • Story words kept the infants' attention about 15% longer

than the foils, an indication that the infants remembered the story words.

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

Learning Language is Incremental

• The same researchers found that infants first learn to distinguish sound patterns of their native 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 with similar sound patterns.

• CNN Interactive: http://www.cnn.com/TECH/9701/22/t_t/babies.birds/

Infant Brain Makes Sense of Language

• A French study found that 3-month-old babies respond to spoken sentences

• Used functional magnetic resonance imaging (fMRI) 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 a foreign language.

The Language Spurt• At about 18 months there is a sudden dramatic

increase in word use• Vocabulary increases to about 100 words and

quickly expands• This change, called the naming explosion or

vocabulary spurt, is a key stage in development• Traditionally explained as the result of

progressions in conceptual development• Woodward et al at the University of Chicago

investigated this phenomenon• Showed that children comprehend words

equally well at 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 a plastic 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 a play activity

• Presented two objects on a tray and asked the child to 'put the toma in the box.‘

• Found little difference in rates of word learning and retention between the two groups of infants.

Categorizing• Babies can also categorize words• A study from Johns Hopkins:• "New findings suggest that infants as

young as 9 months use words to begin shaping their view of the world, arranging objects into mental categories, in a process previously associated more with preschoolers than with mere babes."

Development of Reasoning Skills

• 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 reasoning skills

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

• Measured their attention span to different events.

The Research Study• The longer a baby watches, the more likely he

is trying to understand something unexpected• The first test - babies watch a videotape of an

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

• Another object moves off the screen after the first object enters.

• The second test - the screen is removed to show the two objects colliding or not colliding before the second object moves.

Results• Babies watch longer when objects don’t collide• Researchers concluded that they are surprised

because it violates a principle they have learned: for objects 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 humans and objects to react to each other in the same way.

• The findings support the conclusion that by seven months, infants differentiate between people and objects in their reasoning about simple causal sequences