Chapter 7 (1).docx

Chapter 7 • The effects of environmental influences during infancy and early childhood are often more lasting and pervasive than during any later phase of the life cycle • The National Down Syndrome Society is the largest national organization advocating for Down Syndrome and has a hotline Physical Development • Major systems for physical development: gastrointestinal, renal, endocrine, skeletal, reproductive, neurological • Systems that are closely related to the learning process: neurological, skeletal, and muscular o Functionally related and thought of as one – the neuromotor system • Neurological and motor functions are influenced by important stimuli, and responses are provided by the endocrine system Neuromotor Development • Neurological system: is composed of the brain, spinal cord, and peripheral neurons, including the autonomic system (functionally related to the endocrine system o Neurological pathways extend to muscle and skin tissues and provide for transmission of neurological sensations from the environment to the central nervous system o Also serves as a means for neurological control and response between the central nervous system and the muscles o Neurological functioning cannot usually be studied directly • Indirect investigation often occurs by observing a variety of performance areas and comparing a child’s functioning with age- appropriate levels Head and Brain Characteristics • Achild’s neurological development and capacity are related to head and brain size • The brain grows very rapidly during the prenatal period o This rapid growth continues after birth o A2 year olds brain is approximately 90% of adult brain size  May be indirectly assessed by measuring the head circumference o Normal circumference ranges for each gender and each difference stage  Example: the mean head circumference for male infants at birth is 34.5 centimeters and reaches 49 centimeters by age 2  Example: Female infants have a mean head circumference of 34 centimeters at birth and reach 48 centimeters by the age of 2 o Head sizes considerably larger or smaller are cause for concern  If this occurs, medical testing to determine whether a pathological condition is present that threatens physical health or intellectual functioning must be done • Example: microcephaly – the head circumference is below the norm by two standard deviations or more  Limited brain size tissue abnormalities, or both may result from a genetic condition or from brain infections and other environmental circumstances that slow the growth of brain tissue  Hydrocephalus – a condition characterized by exceptionally large head size even though the brain may be inadequately developed or normal • Related to an increase in the amount of cerebrospinal fluid that circulates in the brain cavity and spinal column area. Puts pressure on the surrounding structures and leads to damage of brain tissue and ultimately to intellectual disabilities, regardless of initial capacity • During the early years, sulci, or convolutions, in the lobes of the brain deepen and become more prominent and numerous during this period • Reflects the process of learning, memory, and the ability to reason and form conceptualizations • Some information concerning the size and shape of the brain can be obtained by x-ray or MRI procedures Myelinization • Myelinization involves the development of a protective insulating sheath surrounding the brain and neurological pathways o Allows nerve impulses to travel along the nerve pathway rapid and without diffusion o Proceeds in a cephalocaudal and proximodistal fashion  Provides for the pattern of acquisition of gross-motor control before fine-motor control • Anewborn has a incomplete myelin sheath, which accounts for nonspecific reactions to stimuli and a lack of motor coordination • By the age of 2, a major portion of the myelin sheath is formed, and the child’s motor capacity is relatively mature Reflexes and Voluntary Behaviour • Development of reflex behaviour is thought to have evolved early in human history out of necessity for protection • Much of the reflexive behaviour of early infancy gradually fades as voluntary control develops through association pathways of the nervous system • Although involuntary movement on one side of the body may mirror voluntary movement in the opposite side o This action is pronounced in children who suffer damage to the central nervous system o This does not suggest damage unless persisted beyond the preschool years • Predominance of the one-sided voluntary function generally is established fully by the age of 4 Emotions and the Central Nervous system • The limbic system of the brain is located in the central portion of the tissue and surrounds the hypothalamus o Functions specifically to mediate emotional and temperamental dimensions of behaviour o Sensations such as pleasure or discomfort and the individual meaning associated with such experiences, originate and are stored in this system o Other behaviour related to the system: excitement, anger, fear sleep and wakefulness • The feeling response rules most others in early childhood in terms of determining behaviour, indicating that the limbic system is functioning and that associations with voluntary control areas are not fully accomplished Sensory Organs and Cranial Nerves • Development and integrity of cranial nerves and specialized sensory organs o These maturational processes are essential to the child’s ability to receive stimuli from the environment and integrate them into the perceptual and memory components of the central nervous system • Cranial Nerves: distinct neural pathways that provide for the specialized sensory function and motor performance of the sensory and other essential and surrounding muscle structure o Functional maturity by the age of 3 and can be tested by assessing sensory organ functions Taste and smell • Optimal functioning levels for taste and smell are reached during infancy • Achild is able to respond accurately to the sensation that a taste or smell arouses and learns associations between certain tastes and smells and culturally accepted values Hearing • Children with hearing loss seem to have more difficulty with learning • The sense of hearing relies on intact tissue structures between the external ear and the brain cortex, including the important cranial nerves involved in hearing functions • And infants hearing apparatus is mature at birth except in two areas: o (a) Myelinization of the cortical auditory pathways beyond the midbrain o (b) Resorption of the connective tissue surrounding the ossicles of the middle ear • The infants reactions to sound is generalized and involves movements of the entire body • As myelinization proceeds, the child begins o exhibit an ability to localize sound direction • By 2 to 3 months, the child can respond by turning the head toward the sound • An infant does not have fully develop hearing like an adults o Adult like hearing is not present until about age 7 and involves complex cortical functioning, including the ability to listen, to respond with discrimination, to imitate sounds accurately, and ti integrate the meaning of sounds. Visual • Visual acuity is rather limited at birth, although vision is fully developed by about age 6 • The new born can differentiate only generally between light and dark • By 6 months, an infant can recognize objects and people o Can also follow movement in the environment o Complete coordinated eye movements should be evident by the sixth month • Amblyopia: When a child is unable to see a single object when looking at it with both eyes (binocularity) o Sees two separate, overlapping objects instead of a single, unified perception o He/she blocks the perception of one eye in order to see a single object through the preferred eye  This leads to gradual deterioration of the neural pathways form the eye o the central nervous system • Integration of incoming visual stimuli with existing neurological functioning’s is very important in early learning • By about 2 to 3 years of age, the child begins to remember and recall visual images o The child begins to enjoy producing geometric shapes and figures o Recognizing symbols typically appears by the time the child is 4 years old o Colour recognition established by 5 Summery • The ability to maintain focal attention also appears in early childhood • An inadequacy in one dimension of the development of the nervous system is typically accompanied by inadequacies in the system generally o The child who has developmental delays in motor performance during early childhood frequently also exhibits delays in emotional development, language development, and cognitive development  Each of these dimensions rely in the general adequacy of the nervous system Effects of the Environment • Each of the child’s neuromotor capabilities has an optimal time during the developmental cycle for appearance and integration into the system as a whole • The child’s development of these specific capabilities during such periods is vulnerable to disruptions that can produce either temporary or permanent problems • Investigations on the effect of early environmental experience represent important research in the field of intellectual disabilities and behavioural science in general • Extreme environmental deprivation can result in pervasive developmental delays and potential intellectual disabilities • Considerable evidence suggests how sensory deprivation of visual stimuli during early life effects a child o For example: significant delays appear in the development of both motor and cognitive performance in infants and toddler who are blind • Belief that a wealth of sensory stimulation during the first 2 years, regardless of type, should promote favorable development of a child’s cognitive and intellectual sills • Limited environmental stimulation, a lack of systematic or order interpretation and mediation, or limited motivation may bring about stimulus deprivation and, with it, limitations in the development of intelligence • Anumber of factors prevent a systematic accumulation of data on the effects of deprivation o The ethics of using human subjects o Occurrences of natural events that result in environmental deprivation are unsystematic and involve such situational variation that investigation of these instances provides data of only limited values  Because of these impediments to studying deprivation, many researchers have turned to study stimulus enrichment in an effort to gather evidence about the influence of environmental sensory stimuli on the development of intellectual functioning • Research has investigated the influences of both visual and auditory stimulation during the early months of life and have demonstrated that controlled stimulation has marked effects on the rate and quality of specific aspects of development • CarolinaAbecedarian Project research involved comprehensive intervention in a variety of family environment areas and also included direct infant stimulation • We can safely conclude that sensory stimulation is beneficial in affective the rate and perhaps the quality of all traits that depend on development of the neuromotor system Professional and Parental Intervention • Health care workers are the professionals most often in contact with young children, particularly physicians and public health nurses o These individual frequently depend on the aid comprehensive services to families with multiple problems and needs • Screening is a very important process in the overa