Textbook Notes (368,107)
Canada (161,650)
Psychology (9,695)
PSYB65H3 (479)
Ted Petit (185)
Chapter 13


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Ted Petit

CHAPTER 13 NEURAL DEVELOPMENT AND DEVELOPMENTAL DISORDERS BRAIN AND DEVELOPMENT brain dvpmt completed sometime in adulthood Overview of modules -> module 1 many signif. Behavl changes that happen in childhood correspond w/ periods of brain growth/orgzn critical periods of dvmpt (prenatal, postnatal) of CNS how they relate to various behavl changes seen in infancy childhood teenage -> module 2 #CNS dvmptl disorders emergent at birth sometime later in childhood MODULE 13.1 NEURAL DEVELOPMENT Early Development [1] virtually every human being started off as an egg cell from fusion of two haploid cells sperm cell egg cell [2] EARLY EMBRYONIC STAGE (approx 3 weeks after conception) [D] NEURAL PLATE = patch of cells on embryo's dorsal surface that gradually become NS forms from ectoderm of embryo [D] ECTODERM= outermost of 3 cell layers that're in early embryo; will form: NS skin's epidermis cells of dorsal ectoderm in neural plate are stem cells => [D] STEM CELLS = embyronic cells capable of dvping into any cell in body .... that're PLURIPOTENT => [D] PLURIPOTENT = cells capable of dvping into diff. Types of cells by diff types of cells, it means only those cells that are in NS [3] DEVELOPMENT PROGRESSING IN EMBRYO neural plate starts to form groove, which 24 days after conception fuses to arise NEURAL TUBE [D] NEURAL TUBE = tube formed out of ectoderm in embyronic day 24 will gradually become spinal cord & brain => diff. Sections of this tube become diff pts of NS ex. Interior surface becomes ventricles central canal of spinal cord B/WEEN THIRD AND FIFTH MONTHS OF GESTATION dominant events occurirng here are 1- rapid cell proliferation => [D] PROLIFERATION = process of cell division that results in new neurons 2- neural migration (euronal migration is the method by which neurons travel from their origin or birth place to their final position in the brain.) EMBRYONIC DAY 40 3 prominant bumps on neural tube's anterior portion >- eventually form CNS's forebrain midbrain hindbrain p404 [1] GLIA neurons migrate from interior ventricular zone to their final destination by following certain types of glial cells NOTE ABOUT CNS DVMPT stages of proliferation & migration BEGINNING OF SECOND MONTH OF GESTATION signif. Growth of telencephalon dvps from cortical plate migration happens from inside out ie. W/ the inner surface turned outward deepest neuron layer that dvp first subseq. Layers must mgirate thro. Already dvped neurons to reach their final loc. [2] DIFFERENTIATION occurs after neurons migrate along w/ diff'n, neurons are starting to dvp axons dendrites pretty much complete at birth => virtually all of it is done prenatally >- contrast: NEURITE DEVELOPMENT occurs prenatally, and postnatally axons & dendrites must get to their approp. Targets & estblish fcnal synaptic connexions unknown as to what is precise mchsm as to how axons grow toward target what is known is that tips of growing axons & dendrites follow chem's which makes them arrange themselves in an orderly manner in position relative to their initial place on cortical plate [3] ABNORMALITIES IN CNS significant cases can result if there is prob. W/ any phase of prenatal dvmpt, having drastic impact on final form that brain takes on LAST 4-5 MONTHS OF GESTATION brain particularly vulnerable ADVERSE EVENTS can arise from a) issues w/in neurons ex. genetic/chromosomal abnormalities or p405 b) external factors ex. Intrauterine trauma ex. Toxin exposure (ex. Pb, alcohol) what effect this disruption has dep. On disruption's nature (characteristics) duration (how long it lasts for) extent (how intense was its effect) [1] what type of CNS deformity results can hint at when disruption happened (ex) (Nolte, 1999) one CNS deformity present from birth happens due to neural tube failing to close happens in 1 in 1000 live births if it does not close completely, this is fatal resultant condition = CRANIOACHISCHISIS = fatal defect of neural tube that results when neural tube completely fails to close CNS appears as groove in top of head and body WHAT IS RESULT OF PARTIAL CLOSE OF NEURAL TUBE? can get syndromes like: (ex) ANCEPHALY =typically fatal failure of rostral portion of neural plate to fuse >- characteristic: general absence of cerebral hemispheres not all neural tube defects are fatal >- (ex) SPINA BIFIDA = neural tube defect that is not necess fatal, but varies wrt its severity >- characteristic: spinal cord defects happens when what subtype of spina bifidia a person has symptoms dep. On which pt of neural tube did not close results in neurological difficulties assoc. Not w/ cognitive difficulties, but w/ movmt this is consistent w/ syndrome having its main effect on spinal cord if this failure ocurs later on in dvpmt, then can have other abnormalities as well, which differ in their severity
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