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Development of the NS start with a single cell that begins to divide!
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Neurulation Gives rise to neural tube (which gives rise to the CNS)
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Neurulation http://worms.zoology.wisc.edu/frogs/neuru/keller_ neur.html http://worms.zoology.wisc.edu/frogs/neuru/keller_ neur.html
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CNS development What determines what and where a neuron should be? very complicated – numerous models; pluripotent (versatile) to begin with role of nearby chemical factors that can influence things
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How do neurons get to where they need to be? cortex has multiple layers with different size/shape neurons - radial glia in cortex
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Neuronal migration in cortex http://rakiclab.med.yale.edu/pages/corticalNeuron Migration.php http://rakiclab.med.yale.edu/pages/corticalNeuron Migration.php http://www.youtube.com/watch?v=ZRF- gKZHINk&feature=PlayList&p=B3AD14F3484810F E&playnext=1&playnext_from=PL&index=24 http://www.youtube.com/watch?v=ZRF- gKZHINk&feature=PlayList&p=B3AD14F3484810F E&playnext=1&playnext_from=PL&index=24
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Other regions - growth cones and “lamellipodia” cell attractants and repellants
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http://www.youtube.com/watch?v=Fgmt2RBow0I& feature=related
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Once neuron reaches destination; it needs to form synaptic connections make neurotransmitter elongate its axon make postsynaptic and presynaptic receptors JUST TO NAME A FEW THINGS!!!
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Some things that happen during CNS development apoptosis – “programmed cell death” what controls apoptosis many things! activity drugs? environment?
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Amazing it all works!!!! two disorders where brain development does not go quite as planned autism and Fetal Alcohol Syndrome similar in that these both involve changes in brain during developmental; developmental disorders differences one is preventable!
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Autism characteristics: Delayed or unusual speech patterns High pitched or flat intonation Lack of slang or "kidspeak" Difficulty understanding tone of voice and body language as a way of expressing sarcasm, humor, irony, etc. Lack of eye contact Inability to take another's perspective (to imagine oneself in someone else's shoes) hypo or hypersensitive to environmental stimuli http://www.youtube.com/watch?v=FuWWie1DlJY
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Additional personality characteristics Engage in repetitive behaviors and ritualized activities, ranging from lining up items to following a rigid routine; OCD symptoms Have one or a few passionate interests, Have difficulty in making and keeping multiple friends, Prefer activities that require relatively little verbal interaction.
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Incidence of autism
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Evidence for CNS? possible deficits in complex or higher order cognitive abilities evoked potentials auditory and visual ERPs altered processing of emotional facial expressions - ERPs
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Developmental Issues Following Fetal Alcohol Exposure
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Definitions Teratogen: a substance capable of interfering with fetal development Teratology: the biological study of birth defects Behavioral Teratology: the study of how agents can affect behavior (so affects brain)
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Historical View of Alcohol as a Teratogen “Foolish, drunken, or harebrain women most often bring forth children like unto themselves” Aristotle in Problemata “Foolish, drunken, or harebrain women most often bring forth children like unto themselves” Aristotle in Problemata “Behold, thou shalt conceive and bear a son: And now, drink no wine or strong drink.” “Behold, thou shalt conceive and bear a son: And now, drink no wine or strong drink.” Judges 13:7
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“… the idea of germ poisoning by alcohol in humans may be safely dismissed…” “… the idea of germ poisoning by alcohol in humans may be safely dismissed…” Journal of Studies on Alcohol, 1, 1940 “The offspring of alcoholics have been found defective not because of alcoholism of the parents but because the parents themselves came from a defective stock.” “The offspring of alcoholics have been found defective not because of alcoholism of the parents but because the parents themselves came from a defective stock.” Journal American Medical Association, 132:419, 1946 Journal American Medical Association, 132:419, 1946 Ethanol drip was used to treat premature labor. Ethanol drip was used to treat premature labor. 1973: First scientific paper naming Fetal Alcohol Syndrome 1973: First scientific paper naming Fetal Alcohol Syndrome Alcohol as a Teratogen: 20 th Century
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Fetal Alcohol Syndrome Fetal alcohol syndrome is the leading preventable cause of mental retardation. What is it, how does it affect people, what can we do about it?
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Fetal Alcohol Syndrome: Diagnostic Criteria Pre- and/or postnatal growth deficiency Pre- and/or postnatal growth deficiency Evidence of central nervous system dysfunction Evidence of central nervous system dysfunction Specific pattern of facial features Specific pattern of facial features
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Streissguth, 1994 FAS: Characteristic Facial Features
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FAS – Only the tip of the iceberg Fetal alcohol syndrome Fetal alcohol syndrome Fetal alcohol effects Fetal alcohol effects Clinical suspect but appear normal Clinical suspect but appear normal Normal, but never reach their potential Normal, but never reach their potential Adapted from Streissguth
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Fetal Alcohol Spectrum Disorders (FASD) ARND: Alcohol-Related Neurodevelopmental Disorder ARBD: Alcohol-Related Birth Defects
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Statistics Approximately 1 FAS birth out of 1000 live births in the US Approximately 3-6 FASD births out of 1000 live births in the US Estimated costs 2.8 billion/year
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Cause of FASD The sole cause of FASD is women drinking alcoholic beverages during pregnancy. Alcohol is a teratogen. “Of all the substances of abuse (including cocaine, heroin, and marijuana), alcohol produces by far the most serious neurobehavioral effects in the fetus.” —IOM Report to Congress, 1996.
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more than 130,000 pregnant women/yr in US drink at levels that may increase risk of FAS rates of frequent and binge drinking in pregnant women have NOT declined in the last 8 years Data from recent CDC report
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FSIQVIQPIQ 40 55 70 85 100 115 Standard score IQ scale NC PEA FAS * * * ** * * General Intellectual Performance
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2 1 3 1 2 3 Group 0 2 4 6 Rule Violations NC PEA FAS P<0.001 Move only one piece at a time using one hand and never place a big piece on top of a little piece Starting position Ending position Mattson, et al., 1999 Executive functioning deficits
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hyperactivity, response inhibition deficits, attentional problems, motor coordination deficits, executive function (planning) problems, Behavioral characteristics associated with Fetal Alcohol Spectrum Disorder
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Poor judgement Attention deficits Arithmetic disabilities Memory deficits Problems with abstract thought Impulsivity Easily victimized unfocused or distractible difficulty handling $$ difficulty learning from experience difficulty under- standing consequences poor frustration tolerance Clinical Implications…..
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Secondary Disabilities of Persons With an FASD = Age 6+ = Age 12+ = Age 21+ Percent of Persons With FAS or FAE Who Had Secondary Disabilities
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Evidence for CNS damage plenty of data cerebellum cerebral cortex corpus callosum basal ganglia
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Brain damage resulting from prenatal alcohol photo: Clarren, 1986
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*** ** CerebrumCerebellum 75 80 85 90 95 100 PEA FAS <p 0.001 p < 0.010 Cerebrum Cerebellum Corpus Callosum Mattson et al., 1994 Change in brain size
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Corpus callosum abnormalities Mattson, et al., 1994; Mattson & Riley, 1995; Riley et al., 1995
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Risk Factors Dose of alcohol Dose of alcohol Pattern of exposure - binge vs chronic Pattern of exposure - binge vs chronic Genetics Genetics Maternal characteristics Maternal characteristics Reactions with other drugs Reactions with other drugs Nutrition Nutrition Developmental timing of exposure Developmental timing of exposure
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Body and Brain Develop in Different Stages in Pregnancy
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Growth retardation Facial characteristics Heart, skeletal defects Microcephaly Reductions in basal ganglia and cerebellar volumes Callosal anomalies Hyperactivity, attentional problems Inhibitory deficits Impaired learning Perseveration errors Feeding difficulties Gait anomalies Hearing anomalies Animal models – Example of the comparability of effects Driscoll, et al., 1990; Samson, 1986;
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Alcohol-Exposed Rodent Models Show Same Behavioral Deficits Hyperactivity Motor Deficits
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Interventions protective factors interventions and stable environment and guardianship (for kids as they grow up) numerous programs exist – maybe not enough but progress is being made
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Pharmacotherapy and/or environmental manipulations environmental enrichment
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EE Reduces many of the behavioral deficits reported increases dendritic spines (in controls and drug treated)
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Pharmacological manipulations drugs that increase cholinergic activity reduce glutamate activity just naming a few – seem to reduce some of alcohol’s effects on the developing brain
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