Brian and behavior ch 9
Brian and behavior ch 9 Nsci3300
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This 0 page Class Notes was uploaded by Caoimhe Notetaker on Tuesday November 10, 2015. The Class Notes belongs to Nsci3300 at Tulane University taught by Paul Colombo in Summer 2015. Since its upload, it has received 43 views. For similar materials see Brian and behavior in Psychlogy at Tulane University.
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Date Created: 11/10/15
Chapter 9 development of nervous system 11082015 General ideas 0 Amazing nature of neurodevelopment The important role of experience 0 The dire consequences of neurodevelopment error Fertilized egg is totipotent has ability to develop into any class of cell Begin to specialize after about 4 days pluripotent can still become wide range but not ANY Further specialize multipotent different cells within a speci c class Most developed cells eventually become unipotent one speci c cell Phases of neurodevelopment Cell multiplication l 0 Cell zygote 0 Cell division 0 Differentiationl make way to appropriate sites and align with surrounding ces establish appropriate functional relation with other cells 0 Developing neurons accomplish these three things in 5 phases 1 lnductions of neural plate Neural proliferation Migration and aggregation Axon growth and synapse formation Neuron death and synapse rearrangement U39lhUUN Induction of neural plate Tissue that is destined to develop into human nervous system Growing neural plate folds to form neural groove then lips of neural groove fuse to form neural tube inside of which becomes cerebral ventricles and spinal cord A small patch of ectodermanl tissue on the dorsal surface of developed embryo induced by chemical signals from an area of underlying mesoderm layer l organizer Tissue taken from the dorsomesoderm of one embryo the donor and implanted beneath the ventral ectoderm of another embryo the host induces the development of an extra neural plate on ventral surface of host Cells of neural plate embryonic stem cells 0 Unlimited capacity for self renewal o Pluripotent Neural proliferation Once the lips of the neural groove have fused to create the neural tube cells of the tube begin to proliferate o Proliferationgreatly increase in number 0 Does not occur simultaneously or equally in all parts of the tube 0 Ventricular zone most proliferation 0 Complex pattern of proliferation controlled by chemical signals from Midline of ventral surface oor plate and midline of dorsal surface roof plate of tube Migration and aggregation 0 Once cells have been created through cell division they migrate to the appropriate target location 0 O 0 During this period cells are still in immature form Two major factors govern migration Time and location Most cells engage in both radical migration and tangential migration Radical in a straight line outward toward outer wall of tube Tangential right angle to radical Two methods by which developing cells migrate Somal translocation extensions grow in direction of migration and cells move along the extending processes Glial mediated temporary network of glial cells radial glial cells cells engage in radial migration by moving along radial glial network Each wave of cortical cells migrates through already formed lower layer of cortex before reaching destination insideout pattern Neural crest cells develop into the neurons and glial cells of the peripheral nervous system Once they ve migrated they must align themselves with other developing neurons aggregation Mediated by cells adhesion molecules CAMs Gap junctions between adjacent cells have been found to be particularly prevalent during bran development 4 Axon growth and synapse formation 0 Once neurons have migrated to positions and aggregated into neural structures axons and dendrites begin to grow from them 0 O 0 Growth cone tip of axondendrites extends and retracts ngerlike cytoplasmic extensions called llopodia Chemoaffinity hypothesis of axonal development Growth cones are in uenced by a series of chemical signals along route Fasciculation O O The tendency of developing axons to grow along paths established by preceding pioneering axons Topographic gradients hypothesis The growing axons are guided to their destinations by two intersecting signal gradients n Anterior posterior and medial lateral Synaptogenesis depends on presence of glial cells particularly astrocytes Synapses from tons of connections and the pruning of unused connchons 5 Neuron death and synapse rearrangement Neuron death normal and important part of neurodevelopment O O O O O 0 Active process apoptosis Removes excess neurons in a safe neat orderly way If genetic programs for apoptotic cell death are blocked the consequence can be cancer If programs are inappropriately activated consequence can be neurogenetic diseases Nerve growth factor neurotrophin promotes growth and survival Cell death results in massive rearrangement of connections As cells die the space left vacant is lled by sprouting axon terminals of surviving neurons Post cerebral development in Human Infants Prefrontal cortex is the last part of brain to reach maturity Brain volume quadruples between birth and adulthood most in rst 2 years Result form synaptogenesis myelination of axons increase branching of dendrites Synaptogenesis in the prefrontal cortex occurs at a relatively steady rate Myelination increase the speed of axonal connection myelination of prefrontal cortex continues into adulthood Dendritic branching in the cortex duplicated the original pattern of neural migration Mature dendrites can still change their shape Various parts of adult prefrontal cortex seem to play roles in 0 Working memory 0 Planning and carrying out sequence of actions 0 Inhibiting responses that are appropriate in come contexts but not others 0 Following rules for social behavior Young people don t being to demonstrate these functions until prefrontal development has progressed Perspective errors in 7 month 12 month children toy and screen Effects of experience Permissive experiences those that permit the into in genetic programs of brain development to be expressed and maintained Instructive experiences those that contribute to the info in genetic programs and in uence the course of development Critical period experience MUST occur at this time to effect development Sensitive period experience will greatly effect development but can weakly effect development outside this period Neuroplasticity in adults Neurogenesis does occur in adults Enriched adult environment increase neuron production Disorders of neurodevelopment Autism 0 Almost always apparent before age 3 and typically does not increase in severity after that age 0 Core symptoms not all present 00000 O O O Reduced ability to interpret emotions and intentions of others Reduced capacity for social interaction and communication A preoccupation with a single subject or activity Older parent increase likelihood of autistic children 80 autistic male 50 suffer retardation 35 have sever seizures Spectrum disorder Asperger s low on spectrum a Linguistic and cognitive function preserved Main signs Delayed development of language and social interaction Minor anomalies of ear structure Autism heterogeneous Impaired in some areas ne or superior in others Autistic savants 10 are savants and 50 of savants are autistic Triggered by several genes interacting with environment Spend less time looking at faces remember faces less well Might be de cient in mirror neuron function 0 Williams syndrome 0 O O O 0 000000 Social empathetic and talkative Almost opposite of autistic High language abilities considering low IQ avg 60 High language abilities often lead to teachers overestimating their cognitive abilities and they don t receive help they need Strength in music but cannot learn to read music Some have perfect pitch and an uncanny sense of rhythm Remarkable ability to recognize faces Severe attention problems Bad spatial ability cant draw objects Health issues heart conditions Thinning of cortex and white matter greatest at orbitofrontal Resemble elves leprechauns and pixies in image and abilities
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