Basis of Behavior
346- Psychology of Exceptional Children
(1-20-15)
Categories of biological contribution to phenotypical development (Cattell, 1950)
Hereditary-direct parental contribution
Innate-mutation and segregation of genetic material
Congenital-acquired in uterus; occurring between conception and completion of the birth process
prenatal effects: acquired in uterus
natal effects: associated with the birth process
Constitutional-alteration of body by life experience
Hereditary Influences: Mechanisms of Genetic Transmission
Biological foundation
chromosome, genes, alleles, DNA
karyotype: arrangement of chromosomes in standard order
mitosis: common cell reproduction
meiosis: cell division from germ cells (46 chromosomes) to gametes (sex cells) (23 chromosomes)
Classical genetic principles: Gregor Mendel, 1866
dominant and recessive characteristics: relationships between genes
phenotype, genotype
Exceptions to Mendelian Inheritance
additivity: blood type
polygenetic inheritance: height, neural tube defects, possibly aspects of intelligence
imprinting
Angelman Syndrome and Prader-Willi Syndrome usually arise from deletion of genetic material from a site on chromsome 15 (15q11-13). If the deletion occurs on the chromosome 15 inherited from the mother Angelman syndrome results, if from the c15 passed from the father Prader-Willi syndrome results.
Seeming exceptions to Mendelian inheritance: sex-linked characteristics
Autosomes and Sex Chromosomes
X-linked characteristics
Hemophilia
Red-green color blindness
Baldness
Some forms of muscular dystrophy, anemia, albinism
X chromosome inactivation in females
Hereditary Influences
Recessive gene disorders (1000+ catalogued)
Phenylketonuria (PKU)
one of over 23 Overflow Aminocidurias
Gene for human phenylalanine hydroxylase is on chromosome 12.gene incidence app. 1 in 100
occurrence app. 1 in 10,000 to 15,0000 live birthsIQ usually below 50, often below 20
Disturbance in pigment formation yields affected children with fair, lightly pigmented skin, blond hair, and blue eyes. A "sweet" or "mousy" (animal-like) odor is reported. No specific dysmorphic features. App. 25% major motor seizures.
treatment by 65 days, mean IQ 93+16
treatment 1st month: 95
treatment 2nd month: 85
Termination of diet is followed by neuropsychological and behavior problems.
It is especially important that women with PKU return to a diet before becoming pregnant to decrease risks of congenital abnormalities and mental retardation in children exposed prenatally to high levels of maternal phenylalanine.
Glactosemia
inborn error carbohydrate metabolism
app. 1 in 62,000 live birthsClinical expression is variable: untreated infants may die of liver and kidney failure, some degree of mental retardation was common, vision impairments due to cataracts.
With careful dietary management, intellectual functioning is usually found to be in the normal range; speech, language, and visuospatial deficits may still be over represented.
Tay-Sachs Disease (Amaurotic Family Idiocy)
one of a number of recessive lipid diseases characterized by a regressive course
1-22-15
Family Microcephalus
anomaly of cranial formation: sever MR
Hypothyroidism (Inherited Cretinism)
absence, insufficiency, or error in production of thyroid hormone
Dominant Gene Disorders (1200+ catalogued)
Tuberous Sclerosis Complex (previously known as Epiloia: epilepsy + anoia [mindlessness], an inappropriate and pejorative label for the disorder since up to 30% may show normal range intelligence)
tumors of brain & skin
Tuberous sclerosis results from an autosomal dominant trait with variable penetrance and a high mutation rate (Harris, 1998, p. 297)
Huntington's Chorea
progressive neurological deterioration
Primary Microcephaly
likely mild MR or borderline intellectual functioning
Neurofibromatosis
(NFI) chromosome 17
Innate Influences
Autosomal nondysjuctions
Down's Syndrome (Trisomy 21, "Mongolism" was the term used by Edward Down, the British physician who gave the early, English language description of this pattern of developmental disorder)
App. 7,000 infants in the U.S. are born with Trisomy 21 (Harris, 1998, p. 272)
App. 1 in every 600 live births.moderate to mild MR, app. 10% in borderline to low normal range
"distinctive" face (facial stigmata): epicanthan fold, upturn, outward slanting eyes, wide nasal bridge, brachycephaly, large tongue and lips, furrowed tongue; short stature; broad hands with short fingers; congenital heart defects (50%)
Incidence correlated with maternal age.
Some cases result from paternal nondisjunction, which appears less correlated with the father's age.estimates set maternal nondisjunction in approximately 80% of cases, paternal nondisjunction in approximately 20% of cases (Jongbloet, Mulder, & Hamers, 1982)
Three main types:
95% cases due to meiotic nondisjunction of autosomal chromosome pair 21 resulting in triplication of the entire 21st chromosome.
4% cases involves translocation of a portion of chromosome 21q to another chromosome
1-2% mosaic form, may be under recognized, two cell lines, one trisomic and one normal, usually less severe impairment
Trisomy 22, 18, 13, 14, 15, 8Trisomy 18: Trisomy E; Edward's Syndrome
Trisomy 13: Patau Syndrome, Bartholin-Patau
MR and physical defects
Sex Chromosome Nondysjunctions
Klinefelter's Syndrome (47, XXY)
Turner's Syndrome (45, XO)
Est. to be among most common chromosomal abnormalities, showing in 3% of early fetuses; but live birth frequency of 1 in 2,500 to 5,000 female births--suspected that 99% of affected fetuses spontaneously abort
short stature; "streak ovaries", failure of gonadal differentiation; characteristic neuropsychological profile:
intelligence usually in normal range
"spatial deficit": problems with space-form perception, spatial skill, left-right discrimination, visuomotor coordination, visual memory, lower Performance IQ than Verbal IQ scores
XYY Syndrome: so called "super male" syndrome
Structural Abnormalities
Ring Chromosomes (usually Ring 18): MR
Chi du Chat's Syndrome (short arm one #5)
Williams Syndrome (Williams-Beuren) (#7)
"elfin" face ("Williams syndrome face")
characteristic social disinhibition and friendliness toward adults, including strangers
impaired visuospatial abilities, poor performance on facial discrimination tasks, hyperactivity, mental retardation, extreme acuteness of hearing
hemizygous deletion on chromosome 7 in 97% of cases evaluated
Prader-Willi Syndrome
most involve deletions or rearrangement of chromosome 15
40% deletion, 30% rearrangement, 30% no discernable chromosomal abnormality, possibly point mutation
mild to borderline MR, poor visual-spatial skills, appetite disorder, physical features
Mutations
Tuberous Sclerosis Complex
25% of clinical cases may reflect spontaneous mutations
Cardio-facio-cutaneous (CFC) syndrome
a sporadic, complex developmental disorder: involves craniofacial features, cardiac anomalies, hair and skin abnormalities, postnatal growth deficiency, hypotonia, and developmental delay
heterogeneous de novo missense mutations in three genes within the mitogen-activated protein kinase (MAPK) pathway cause CFC syndrome. In the majority of cases there is a mutation in the BRAF gene, located on 7q (Rodriguez, et al., 2006)
familial ideopathic epilepsy:
an inherited epilepsy of newborns
found to be one of the "channelopathies", or disorders of ion channel function, associated with mutations in genes coding for a potassium channel
unstable triplicate expansions: new mechanism of dynamic mutation due to heritable unstable DNA elements
Fragile X syndrome
FMR-1 (fragile X mental retardation) gene
Prevalence of fragile X estimated to be 1 in 1,250 males and 2 in 2,500 females; found in all human gene pools. One of the more common known causes of mental retardation.
Affected individuals show a repetitive DNA base sequence (CGG) of at least 230 repeats at the Xq27.3 site; 52 to 230 repeats produce an asymptomatic permutation carrier state; 6 to 54 repeats represent the normal range.
Behavioral phenotype: mental retardation, ADHD, gaze aversion, speech and language delays in children with normal IQ
possibly Huntington's chorea
Congenital Influences
Prenatal
General Condition of the Mother
Malnutrition
Specific Dietary Deficits
Vitamin D: Rickets
Iodine: Cretinism
Maternal Illness
TORCH group (Toxoplasmosis, Rubella, Cytomegalovirus, Herpes, Syphilis)
the "Rubulla bulge" refers to children born with Rubulla related birht defects resulting from 1964 epidemic of "German measles"; an estimated 20,000 to 30,000 children were affected with approximately 8,000 born deaf, 3,500 born blind, 1,790 cognitively impaired. (Thompson & O'Quinn, 1979)
Rubulla as been virtually eliminated in the U.S.
HIV
Blood Type Incompatibility
Rh- mothers; Rh+ children
ROGAM
1-27-15
Drugs: quantitative vs. qualitative effects
Thalidomide
Progestines: Progestine-induced hermaphroditism
Alcohol: Fetal Alcohol Syndrome
Nicotine
Chemical Toxins: PCB's and IQ
Radiation
Natal
Anoxia
Fetal Distress
Cerebral Palsy
Prematurity (& Postmaturity)
Gestation age vs. gestation weight
Birth Weight (premature)--% Disability (IQ<70, CP)
<1,500 grams ----------------4%
<1,000 grams ----------------10%
< 750 grams -----------------18%
Constitutional
Illness
Toxic Exposure
Brain Injury
Learning (experiential) influences on development
Mechanisms of Learning
respondent (classical or Pavlovian conditioning):
associative learning based on contiguous pairing
esp. relevant for maintenance of homeostasis and possible
development of emotional behavioroperant (instrumental)
learning from consequences (rewards, punishments)/contingencies
esp. relevant for influencing the level of performance/frequency of actionsobservational (vicarious learning, modeling)
learning from noting the actions and experiences of others, may be
symbolic (based on stories, reading, etc.)
esp. relevant for language acquisition and social development
Social Interaction
Among the major effects of social engagement are:
1) attachment phenomenon
2) language development
3) cognitive development (Vygotsky)
4) social skill acquisition
5) self-image, gender identity, values & attitudes
The agents of social development include:
1) parents
2) siblings & extended family
3) peers
4) subgroups (clubs, church/synagogue/mosque, gangs)
Interaction of Biology and Experience
Temperamental traits (possibly more biological) interact with child rearing patterns (possibly more experiential)
to produce unique outcomes, for good and ill.
Children influence, as well as are influenced, by their environments.
Risk and protective factors are often interactive: their joint effects are seldom simply additive or linear.
2 risk factors are usually worse than 1, but often are more then "twice" as bad as 1.
Particular combinations of risk factors are often especially destructive (or more benign):"difficult temperament" + inconsistent parenting is an especially unfortunate combination.
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