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Chapter 5

Chapter 5

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Konstantine Zakzanis

PSYB20 Chapter 5 CHILD’S GROWTH pages 156-167 BRAIN DEVELOPMENT IN FANCY - At birth, 1/4 size of mature brain. 6 months, half. 2 years, 75% - Cerebrum: Two connected hemisphere; largest part of brain. ▪ Embodies shared attributes of animals & uniquely human attributes - Cerebral Cortex: Covering layer of human cerebrum ▪ Contains 90% of brain’s cell bodies ▪ Specific function > Specific cortex NEURONSAND SYNAPSES - Neurons: 100-200 billion at birth, most already present at 7 months gestation - Neuron proliferation: When neurons multiply at rapid rate during embryonic stage - Brain cells can be regenerated - Brain size increase as neurons & connections increase - Glial cells: provide structural support, regulate nutrients, and repair neural tissue ▪ Some glial cells responsible for Myelination  Covering parts of neurons with fatty wrapping (myelin), makes it easier to transmit information  Mostly occur during first 2 years but some continues into adulthood - Neural Migration: movement of neurons within the brain that ensures all brain areas have sufficient number of neural connections ▪ Absence of sufficient neurons associated with mental disabilities and disorders - Synapses: Specialized sites of intercellular communication where info is exchanged between nerve cells, usually by means of chemical neurotransmitters, from axons to dendrites. ▪ Crucial for learning and survival ▪ Grows by creating new synapses after receiving input from the environment, allowing for more complicated and sophisticated communications - Synaptogenesis: forming of synapses. ▪ Begins early in life and continues to adulthood. - Not all neurons & synapses are necessary or functions through life ▪ Two processes that regulates this: a) Neuronal Death: (programmed cell death) to provide space for crucial loco of info transmission b) Synaptic Pruning: brain’s disposal of axons& dendrites of not so stimulated neurons frees up space for new synaptic connections ▪ Goal of both is to increase speed, efficiency, and complexity of transmission and to form new synapses as new experiences are encountered - By adulthood: 1 trillion neurons making 100-1000 connection = 1 quadrillion synapses. SEQUENTIAL DEVELOPMENT OF BRAIN - There is an orderly sequence to brain development during infancy ▪ 2 months: motor reflex drop out, motor cortex begins to oversee voluntary movements ▪ Similar processes occur in vision, olfaction, and audition. HEMISPHERE SPECIALIZAITION – begins early in life - Two hemispheres, both anatomically and functionally different, connected by corpus callosum. - One side of the brain can take over the functions of the other side (plasticity) - Lateralization: specialization of each hemisphere in specific perceptual & cognitive tasks. - RIGHT - Functions - Effects when damaged - Visual special information - Difficulty in attending to - Non-speech sound recognition visual-spatial perception tasks - Face perception - Spatial disorientation - Emotion processing - Difficulty in facial perception and - Activated in expression of emotions expression associated with withdraw to external - Trouble producing emotional tone of environment (distress, disgust, fear) utterance - Trouble understanding emotional state base on speech - Difficulty in processing auditory and musical pitches - LEFT - Functions - Effects when damaged - Language processing - Have trouble understanding content - Activated in expression of of speech emotions associated with approach to - Trouble speaking clearly external environment (joy, interest, anger) - Right side of the brain takes over language functions of people who are deaf and uses sign language (plasticity) ▪ Evidence that the brain can adapt to external influences Consequences of Brain Lateralization - Infants whose left hemisphere differentiates among speech sounds and whose right hemisphere differentiates among non-speech sounds exhibit better language skills at age three than infants who do not show such strong lateralization ▪ However, responses to hearing speech and matching it to objects are multidimensional and involve a multitude of processes. ▪ That is to say the brain’s complicated. Why? Cause why the fuck not. - Lateralization underlies dyslexia 5-10%:American population ▪ Difficulties in integrating visual and auditory information ▪ Some suggest this arises due to abnormal lateralization patterns (Both sides instead of just R side)  Left hemisphere becomes loaded leading to deficit in language skills. - Handedness ▪ Most infants show preference for right hand ▪ Suggests handedness develops in the womb ▪ People who are ambidextrous (use both hands) may have less lateralized brains. BRAIN’S PLASTICITY: EXPERIENCEAND BRAIN’S DEVELOPMENT - Environment plays a role in brain development - Plasticity ▪ Capacity of the brain, particularly in its developmental stages, to respond and adapt to input from the external environment - 2 types of experience influence brain development a) Normal expected experiences (e.g. visual stimulus)  Trigger synaptic development and pruning  Critical for normal brain development  When interfered, basic abilities are impaired b) Unique experiences encountered in particular families, communities and cultures  Respond by developing synaptic connection that encode specific and unique experiences - Size, structure and biochemistry can all be modifies by experience ▪ Enriched environment increase neural complexity (measure by no. of dendrites)  More dendrites= more synapses= more information transportation ▪ Key chemicals essential for healthy brain also increase with enriched environments ▪ Adults are also affected, but not to the extent younger one experience. - Music promotes spatial temporal reasoning ▪ However, there is a large debate with this topic. - Brain can undergo structural changes based on unique experiences even in adulthood ▪ Posterior hippocampi, through to deal with spatial representation of the environment, was larger in taxi drivers than control - Lack of stimulation or exposure to traumatic events can damage brain, causing malfunctions ▪ Cortex and limbic system of abused kids are 20-30% smaller than normal ▪ Reduced connectivity or communication in regions of brain as well as reduced cortical activity. TABLE 5-1 Techniques for styding human brain function and structure Technique What it Shows Pros and Cons EEG - Lines that chart the + detects rapid changes in - Multiple electrodes summated electrical electrical activity, allowing pasted on outside of head fields resulting from analysis of stages of activity of billions of cognitive processing neurons _ Poor spatial resolution of the source of electrical activity - Sometimes combine with MEG which localizes electrical activity by measuring magnetic fields associated with it. PET & SPECT - An image of the amount + allows functional and - Position and photon are and localization of any biochemical studies emission from molecule that can be + provides visual image radioactive substances injected in radioactive corresponding to anatomy form _ requires exposure to radioactivity _ Provides spatial resolution better than EEG but shittier that MRI _ cannot follow changes faster than 30 seconds. MRI - Traditional MRI + Requires no exposure to - Exposes the brain to a provides high resolution radioactivity magnetic field and image of brain anatomy + Provides high spatial measure radiofrequency - fMRI provides images of resolution of anatomical waves changes in blood flow details (under1mm) - DTI shows water flow in Provides High temporal neural fibres, revealing resolution (slower than 1/10 the wiring diagram. of a second) _ Super expensive to operate TMS - Normal function of a +Shows which brain regions - Temporarily disrupts particular brain region are necessary for given tasks electrical activity of a can be studies by _Long term safety not well small region of brain b observing change after established exposing it to an intense TMS is applies to a magnetic field specific location Chapter 5 – 169-175 Locomotion: Development of locomotion has 3 phases and transitions 1) long puzzled researchers Hold a baby upright and let his feet touch the flat surface tilting his body from side to side the baby responds by reflexily moving his legs in a rhythmic stepping motion that resembles walking 1 year of age the baby begins to walk without support there have been many theories developed regarding walking maturation theorist say :walking developed by motor cortex cognitive theorist say: it’s a respond to cognitive plans or representations that are the consequences of watching other people walk also practicing it by stepping in itself Thelen’s dynamic systems theory: says that walking skills are determined by interplay of variety of emotional. Perceptual, attentional, motivational, postural and anatomical factors According to this theory the newborn stepping response disappears for a 10 month interval before true walking emerges because anatomical factors that is the baby’s size and weight become too much of a load on the emerging motor system Thelen provided such support by holding infants on a motorized treadmill, they performed alternating stepping movements they were similar to more mature walking Upright walking is just the beginning by the time kids are about 7 years old they have acquired the more complex skills of running, galloping and hopping Running is established by the time the kid is a year and a half Galloping emerges at about the same time Hopping requires balance this emerges around 2-3 years of age How Locomotion may affect other aspects of development Important concept of locomotion is increased independence New found independent in turn changes the way that others respond to the child Researchers observed that early walking is related to increased parent child interaction and more testing of wills between mothers and their children Researchers have adopted a perception action coupling approach to understanding the growth of such independent mobility, according to this view motor or action systems are functionally interrelated to sensory or perceptual systems such that changes in one aspect influence the development of the other aspect  The onset of locomotion can change the way babies understand their perceptual world Another link between perception and action is done through experiments on the use of vision in balance control ( moving room) Moving room is a room in which the walls and ceilings can be moved back and forth while the floor itself stays immobile Researchers said how young infants and children use visual input produced by moving a room to control their balance, despite the lack of vestibular info that would tell someone about a loss of balance Bertenthal & Bai: speculated that self produced locomotions is critical for infants use of visual info in such situations based on their observations that crawling infatns but not similar age pre crawling ones used moving room input to control their balance The Role of experience and culture Cross cultural studies provided us with info about ways of caring for infants can alter their motor development, when parents or other caregivers give babies special physical attention including manipulation, message, exercise and other practice skills the infants achieve motor millstones somewhat earlier than children not given such care and opportunities For instance moms in Zambia carry their new babies with them everywhere in a sling on their backs, then when they are able to sit the mothers leave their infants sitting along therefore this gives them to practice motor skills Jamaican moms message the babies stretch the arms and legs and give them practice in stepping and their children too are motoric ally advanced Mexician infants are swaddled therefore they have less advanced motor skills Zelazo & colleagues: asked moms of newborns to give their infants practice in the stepping reflex a few mins a day not only did these babies make more walking responses aat 2-8 weeks of age also they walked earlier than a control group of babies Karen Adolph: collected diary records of infants walking activates, these records showed that walking infants practiced keeping balance in an upright stance and locomotion for more than six hrs a day Benson said that infants born in summer and fall months acquired motor skills latern than infants born in the winter or spring months because the former group would begin to develop locomotor skills In the winter to early spring Seasonlity affects have been looked at: Osaka Japan and EdmontonAlberta, in the case Barlett found that these seasonality effects failed to occur in the geographic region of more extreme cold with temperature, Bartlett explains: this difference by noting that even though Edmoton is colder Denver because the infants examined in this study were from the urban environment, thus this study highlights the possibility that constrains imposed by the environment can influence motor development Physical Growth  Study of physical growth is guided by 2 classical principles which are cephalocaudal development and proximal development pattern  Cephalocaudal development: the notion that human physical growth occurs from the head downward that is from brain and neck to trunk and legs  Proximal distal pattern: the tendency for human physical development to occur from the center outward fro example: from internal organs to arms and legs  In a longitudinal study Galloway and Thelen found that young infants reached for objects approximate two weeks earlier with their feet than they did with their hands thus demonstrating more complex motor skills with parts of the body further away from head than body parts closer to the head  Height & weight are principle measure of overall growth  Babies growth faster in their fist half year of life than ever again  Nearly double their weight in the first three months, triple their weight by the end of the first year  Their shape changes as well, as newborns top-heavy light bulb shaped bodies become increasingly cylindered and infants center of mass moves from sternum to below the belly bottom Do genes height and weight  Researchers say that ones height and weight is strongly influenced by genetic factors  Data a longitudinal study that compares many adoptive and biological parents and their adopted and natural children indicates that genetic factors may determine as much as two thirds of the variance of these characteristics  Another researcher scientist found that strong relation between the weights of adopted kids and their biological parents but no relation between adoptees and adoptive parents weights 
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