PSY 3061 1st Edition Lecture 14Outline of Last Lecture I. Answers from last quizII. Lateral inhibitionIII. ColorsOutline of Current Lecture I. Stages of neurodevelopmentII. Induction of neural plateCurrent LectureI. Stages of neurodevelopmenta. Induction of neural plateb. Neural proliferationc. Migration and aggregationd. Cell differentiatione. Axon growth and synapse formationf. Neuronal cell death and synaptic rearrangementII. Induction of neural platea. Three cell layers of the developing embryoi. Ectoderm: dorsal layer, neural plate forms hereii. Mesoderm: middle layer, promotes neural plate development in ectodermiii. Endoderm: inner layer, not strongly involved in neural developmentb. Mesoderm releases chemicals onto ectoderm  induces rapid thickening of the ectodermc. Uneven cell division at the head-end of the ectoderm results in a neural groove  neural crest becomes more apparentd. Neural crests have closed in upon the neural groove resulting in a neural tube (central canal)e. Anterior portion of the neural tube will become the forebrain, midbrain, and hindbrainf. Posterior portion of the neural tube becomes the spinal cordIII. Neural proliferationa. Mitosis  interphase, prophase, prometaphase, metaphase, anaphase,telophaseb. Neural cells proliferate at the ventricular zone of the fluid filled neuralThese 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.tubec. Cells migrate from the site of proliferation to become different structures of the brainIV. Cell migrationa. Cells generated at ventricular zone then migrate either outwardly (radially) or along the length of the neural tube (tangentially)b. Radial migration by glial cellsc. Glial cells extend from inner to outer surfacesd. Migrating cells from the ventricular zone ride along these glia like a train rides a monoraile. Cells of certain types stick together in certain areas to form cohesive groups  occurs because of cell adhesion moleculesf. Cell migration happens in an inside out fashion  oldest cells end up towards the inner layers and younger cells towards the outer layerg. Differentiationi. Once a cell reaches its target destination it begins to take on the shape and function of other cells in that locationii. Changes in ship driven by a change in gene expressioniii. Neighboring cells send a message to new cells to promote expression of particular genesiv. Gap junctions allow cytoplasm to pass between adjacent cellsV. Axon growth, synapse formationa. Over time, dendrites and axons grow outward and form connectionsb. How does the brain form the correct synapsesi. Chemoaffinity hypothesis1. Unlike mammals, amphibian retinal ganglion cells can grow back if severed2. Sperry cut the optic nerve for one eye in a frog to see if the nerve could “find its way home” 3. Growth cone is either attracted or repelled by certain chemical gradients4. Doesn’t explain why cells take complicated routes to certain targetsii. Topographical gradient hypothesis1. Sheets of developing neurons are often characterized by two intersecting chemical gradients which can define thelocalization of each neuroniii. Chemoaffinity and topographical are both based on chemical gradient signalsTopographical gradient hypothesis just extends chemoaffinity into multidimensional