Psyc 2012 1st Edition Lecture 8 Outline of Last Lecture I. Exam 1 study guide- TBDOutline of Current Lecture II. Neural Development: developmental neurogenesis, brain development and environmentA. Today’s lecture goalIII. The Human BrainA. Developmental NeurogenesisIV. Gross Development of the human nervous system- early stages of developmentA. ZygoteB. Blastula or blastocystC. GastrulaV. Formation of the NS in 6 main processesA. Cell proliferationi. Neural stem cell proliferationii. PNET- primitive neuroectodermal tumorB. Cell migrationi. Neural cell migration1. Tangential migration of neural crest cellsC. Cell differentiation i. Two types of differentiation1. Chemical differentiation2. Morphological differentiationa. Chemoattractantsb. Cell adhesion moleculesD. Synaptogenesisi. Cellular activities in both neurons create proper synaptic structureE. Cell death and synaptic pruningi. Key pointii. Neural cell death and neurotrophinsF. Myelinationi. Does not progress evenly throughout the brainCurrent LectureWeek 4- Lecture 8- 2/10Neural development: developmental neurogenesis, brain development and environmentThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Goal: to learn how a structure as complex and incredible as our brain is formed.Plasticity- the ability to change; important concept to keep in mind. How adaptable is the brain?The Human BrainHas about 100 billion neurons, and about 1,00 synaptic connections per neuron.It has even more glial cells, about 10 glial cells per each neuron.All of these cells have a specialized structure and function.Where do all these cells come from and how do they become specialized during development?Developed neurogenesis: the process by which neurons are formed and differentiated during development. This has two main components-1) Forming neurons 2) Specializing neurons; also called differentiation. Gross Development of the human nervous system- early stages of developmentZygote: from fertilization to 4 days old. The zygote begins dividing and forms a ball with multiple cells. Blastula or blastocyst: a hollow ball of cells that forms around 4-5 days. In this stage, any of the cells can become any specialization. Gastrula: 3-layered ball of cells because one end tucks in on itself, forms in 7-10 days. The 3 layers of the gastrula will eventually form different tissues. Ectoderm: the outer layer that forms the skin and NSMesoderm: the middle layer that forms muscle, blood and bone; everything between the guts and skin. Endoderm: the inner layer that forms deep internal organs, like the lungs, liver, intestines, etc. The endoderm then forms other neural structuresNeural plate: part of the back ectoderm that forms the neural tube by folding in on itself.Neural tube: a hollow tube of cells that eventually forms the spinal cord and brain. Neural crest: the cells that eventually migrate out, from either sideof the tube, and form the peripheral nerves. This is the start of the NS. Incomplete folding can result in anencephaly, which is a lack of brain formation that results in fetal death, or spinal bifida, which can cause paralysis as a result of the spinal cord not forming. Formation of the NS in 6 main processes1) Cell proliferation 2) Cell Migration3) Cell differentiation and maturation4) Synaptogenesis5) Cell death and synaptic pruning6) MyelinationKnow which processes are pre-birth, post-birth, or continuousCell proliferation: the formation of 2 daughter cells from 1 parent cellNeural stem cell proliferationStarts shortly after conception and is mostly complete 4-5 months after conception. Forms over 100 billion neuronal precursor cellsMore neurons are formed than are neededWe can’t form new brain neurons after birthPNET- primitive neuroectodermal tumorA rare but dangerous tumor found only in children; they are born with thetumor. Forms because neural stem cells refuse to stop proliferating like normal; this is very rare. Causes hallucinations, seizures, and brain development problems.5-year survival rate is 50%Tumors don’t normally form from brain cells or brain stem cells.Cell migration: the movement of cells from one place to another. This applies to generic stem cells, which crawl along the structures in an ameba. Neural cell migrationStarts around 8-9 weeks post-conception and it complete 2-3 months before birth. Two main types of migration-Tangential: moving up and down or around.Radial: moving outwards from the center.Two main migration events in neural development-Tangential migration of neural crest cells; in order to form Schwann cells and neurons, in peripheral nerves. *This is important to know for the test. Radial migration of cerebral cortical neurons; in order to form the layers of the cerebral cortex. *Check diagram on online lecture notes for further clarification. Cell differentiation: the process by which unspecialized stem cells or precursor cells takeon their final specialized state, and become neurons. Two types of differentiation-Chemical differentiation (pre-birth): hormones and other chemical signals activate master regulatory genes; genes that make a protein which then turns on neuron-specific proteins. Pre-birthNeuron specific proteins include- NT receptors, voltage-gated ion channels, non-gated pumps, peptide NT, NT synthesis enzymes, etc. Proteins are the main “doers” in cellsDifferent sections of DNA turn on in order to create certain proteins. Types of master regulatory genes- muscle, nerve, skin, and every other type of cell. Morphological differentiation: cell taking on its adult form; dendrites andaxons begin to form. Pre-birth to post-birth2 main processes as cells go through maturation-They grow dendrites- increase in length and branching of dendrites. This increases the surface area for synapse formation. They extend axons- extension happens in millimeters and requires 2 cues; 1) target cells secrete chemoattractants to guide the axon to them 2) cell adhesion molecules then grasp the axon and adhere it to the target cell. Synaptogenesis: the formation of a functional synapse between an axon from a presynaptic neuron and the dendrites of a postsynaptic neuron. Starts during prenatal development and continues into late childhood. Cellular activities in both neurons create proper synaptic structure:Pre-synaptic neuron needs to synthesize and store NT vesicles. Post-synaptic neuron needs to