BRAIN & PERCEPTUAL DEVELOPMENT
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Transcript of BRAIN & PERCEPTUAL DEVELOPMENT
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BRAIN & PERCEPTUAL DEVELOPMENT
Feldman Modules 3-2 & 3-3
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• At birth, the brain is at about 30% of it’s adult weight.
• At age 2, the brain is at about 70% of its adult weight.
• Brain reaches 90% of adult weight by age 6
BRAIN DEVELOPMENT
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Prenatal : neurogenesis – 2nd trimester, fetal period
Post Natal (after birth) (cycle) Synaptogenesis – dendrite formation
Synaptic pruning
Myelination
BRAIN DEVELOPMENT
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SYNAPTIC TRANSMISSION
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The human brain has 100 – 200 billion neurons at birth.
During the first two years, fibers from these form synaptic connections at a rapid rate and some neurons die as a result.
BRAIN DEVELOPMENT - SYNAPTOGENESIS
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Experience determines brain development.
Neurons not stimulated lose their synaptic connections.
Neurons often stimulated strengthen connections by growth of new dendrites
BRAIN DEVELOPMENT – SYNAPTIC PRUNING
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BRAIN DEVELOPMENT – GLIAL CELLS AND MYELINATION
Glial cells multiply rapidly during the first two years. (About half the brain’s volume)
Glial cells produce myelin to coat neuron axons. Myelination improves the efficiency of neural transmission.
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CEREBRAL CORTEX
The order in which cortical regions develop corresponds to the order in which capacities emerge in the growing child.
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CEREBRAL CORTEX In the first year, there is a burst of
synaptic growth in the auditory and visual areas.
Areas supporting language show dramatic growth during toddlerhood.
One of the last regions to develop are the frontal lobes.
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BRAIN DEVELOPMENT
Rapid frontal lobe growth at ages 3-6
Myelination of cerebellum-cortex links, reticular formation, corpus callosum
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• Specialization of functions in the two hemispheres of the cortex is called lateralization.
• For most people, language, logic and positive emotion are processed by the left hemisphere. Spatial and wholistic tasks and negative emotions are right hemisphere.
• Lateralization is very plastic.
CEREBRAL CORTEX – LATERALIZATION & PLASTICITY
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• Brain growth spurts, as measured by weight, size and EEG, occur:
3 to 4- months – reach for objects 8 months – crawl, search for objects 12 months – walk 1.5 -2 years – talk Ages 9, 12, 15, 18-20
BRAIN DEVELOPMENT – SENSITIVE PERIODS
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• Results in deficits in:
Concentration
Attention
Anger and other impulse control
BRAIN DEVELOPMENT - UNDERSTIMULATION
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• Does not result in geniuses.
• May cause infant withdrawal.
• May lead to disappointed parents.
• May cause strain between infants and parents.
BRAIN DEVELOPMENT - OVERSTIMULATION
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BRAIN DEVELOPMENT IN ADOLESCENCE
Reward and pleasure centers (limbic system) mature before judgment centers (pre-frontal cortex) do.
Baird & others (1999) found that 10-18 year olds process emotional information using the amygdala, 20-40 year olds use the frontal lobe.
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BRAIN CHANGES IN ADULTHOOD
Production of new neurons throughout life
Growing new dendrites through the 70’s
Brains rewire themselves – functional plasticity
Myelination between cortex & limbic system in 40’s & 50’s
Decrease in lateralization
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MANKATO NUN STUDY Early-life idea density at 22 linked to
fewer incidences of mild cognitive impairment
Positive emotions linked to longevity Teachers showed more moderate
intellectual declines Sisters with high folic acid levels
showed little Alzheimer-like damage
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MENTAL DISABILITIES IN OLDER ADULTHOOD Normal age related cell death in the
brain does not lead to loss of ability to engage in everyday activities.
Dementia: a set of disorders occurring almost entirely in old age and leading to impairment of many aspects of thought and behavior
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DEMENTIAS Alzheimers: most common form
Close to 50% of people over age 80 are affected
Starts with memory loss, faulty judgment, anxiety, aggressive outbursts, reduced initiative, social withdrawal, depression Later purposeful movement may degenerate, may lose speech, lapse into a coma
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ALZHEIMER Neurofibrillary tangles: twisted threads
from collapsed neural structures
Amyloid plaques: deposits of deteriorated protein surrounded by clumps of dead nerve cells
Lowered levels of acetylcholine and serotonin (Drugs limiting acetylcholine breakdown reduce dementia symptoms.)
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ALZHEIMER RISK FACTORS Familial: early onset, rapid progress
Genes on chromosomes 1, 14, and 21 Dominant Related to Down syndrome
Sporadic: no obvious family history Abnormal gene on chromosome 19
leads to excess ApoE4 blood protein that carries cholesterol and is linked to amyloid formation
Some have no known genetic markers
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ALZHEIMER RISKS Toxic substances Viruses Defects in the blood-brain barrier Vitamin and mineral deficiencies Excess dietary fat Cardiovascular disease Head injury Elevated aluminum levels
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PROTECTIVE FACTORS
Vitamin C and E Anti-inflammatory drugs (aspirin,
ibuprofen) Education Active lifestyle
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CEREBROVASCULAR DEMENTIA 5 to 10% of cases Series of small strokes leaves areas
of dead brain cells Risks include high blood pressure,
cardiovascular disease, diabetes Also smoking , heavy alcohol use,
high salt intake, very low dietary protein, obesity, inactivity, and stress
In most cases caused by atherosclerosis
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PARKINSON DISEASE Subcortical dementia
Involves dopamine-producing neurons in the substantia nigra of the brain
Symptoms include muscle tremors, slowed movements, and partial facial paralysis
Drug treatment is partially successful
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REVERSIBLE DEMENTIA Depression Prescription drugs Surgery Environmental changes Social isolation
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SENSORY & PERCEPTUAL DEVELOPMENT
Sensation is detection Perception is organization &
interpretation
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THE NEWBORN – SENSORY CAPACITY
Newborns are sensitive to touch and to pain. Facial expressions show that they distinguish
sweet, sour and bitter. Newborns like the smell of bananas,
vanilla,strawberry & chocolate, but dislike rotten eggs & fish.
6-day olds (but not 2-day olds) prefer the smell of their mother’s breast pad
Infants prefer the sounds of human speech, recognize mom’s voice.
Vision is the least developed sense at birth.
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HEARING – PRENATAL & INFANT The fetus can hear even before birth.
DeCasper & Spence, 1986 – Cat in the Hat research
Newborns need more volume, are less pitch sensitive, not as good at sound localization, and have auditory preferences
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SMELL - INFANT Newborns like the smell of banana,
vanilla, & strawberry & dislike the smell of rotten eggs & fish.
6-day olds (but not 2-day olds) prefer the smell of their mother’s breast pad
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TASTE - INFANT Research adding saccharin to amniotic
fluid showed greater swallow & potential taste sensitivity in fetuses
At 2 hours of age, babies make different faces to sweet, sour, salty & bitter
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VISION Birth, vision is 20/400 – 20/600 1 year – 20/20 visual acuity
By 2 months can focus on objects and discriminate colors as well as adults
Eye movements also under control for scanning and tracking
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DEPTH PERCEPTION
2-3 months – sensitive to binocular cues
6-7 months sensitive to pictorial (monocular) depth cues
Crawling promotes 3-dimensional understanding (affordance of falling)
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THE VISUAL CLIFF
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SENSORY & PERCEPTUAL DEVELOPMENT
The Ecological View (Gibson)
The purpose of perception is for us to adapt to and interact with the environment.
All objects have affordances or opportunities for interaction that fit with out abilities to perform activities.
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SENSORY & PERCEPTUAL DEVELOPMENT – RESEARCH METHODS
Visual preference – length of time the infant looks; reflection in the eyes;
Franz looking chamber
Habituation & dishabituation Decreased responsiveness (looking, sucking, heartrate,
respiration)
Orienting & tracking Turning head or tracking with eyes
Equipment videotape, computer, recording heart rate, etc.
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PATTERN PERCEPTION
• Newborns prefer patterned to plain stimuli
• As infants develop contrast sensitivity they prefer more complex patterns.
• Infants first respond to parts of a pattern, then to the whole pattern.
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FACE PERCEPTION
Newborns prefer simple drawings of faces with features arranged naturally.
2-5 months they prefer a complex face to other complex patterns
2 months, look longer at mother’s face
3 months, discriminate photos of two strangers
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INFANTS – PERCEPTUAL CONSTANCY
Size constancy ( 3 mos. – 11 years)
Shape constancy ( 3 mos.)
By 12 months, perceptual property of closure
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DIFFERENTIATION THEORY
Infants look for stable or invariant features of the environment
Over time, the baby differentiates or detects finer and finer stable features
Some theorists believe that in some sense, the infants impose meaning on the patterns that they perceive.
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VISUAL EXPECTATIONS
Infants form expectations about what they are going to see as early as 3 months
Spelke at 4 months infants recognize the solidity
& continuity of objects At 6-8 months, (but not 4), they perceive
gravity & support
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Perceptual/Cognitive Development• Baby Mathematics
– Shown a numerically impossible outcome, infants stare longer (Wynn, 1992)
1. Objects placed in case.
2. Screen comes up.
3. One object is removed.
4. Possible outcome: Screen drops, revealing one object.
4. Possible outcome: Screen drops, revealing two object.
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SENSES IN ADULTHOOD All of the sensory systems with the
possible exception of touch experience gradual decline as a person ages.
Vision Hearing Taste Smell
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VISION IN ADULTHOOD
Middle Adulthood
Presbyopia, loss of accommodation (ability to adjust focus at different distances) between ages 40 and 59
50’s & 60’s – blood supply to eye declines, need more light, smaller visual field
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VISION IN ADULTHOOD Late Adulthood
Dark adaptation is more difficult Glare sensitivity increases Continuation of degeneration of function
from Middle Adulthood Possible retinal degeneration
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DISEASES OF THE EYE Cataracts – 30% of people by age 70
Glaucoma – pressure from fluid buildup in the eye damages the optic nerve; 1% in 70’s, 10% in 90’s; treated with eye drops
Macular degeneration – deterioration of retina; 1 in 6 people 75+; leading cause of blindness in older adults
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TASTE & SMELL
Ability to taste appears to start decline in the 60’s, leading to a preference for spicy and junk food
Older adults (60 +) lose some of their sense of smell and may enjoy food less