Class4_Development

Class4_Development - Outline Development Stages of neural development Effects of genetics on development Mutant mice Effects of experience on

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1 Development Outline • Stages of neural development • Effects of genetics on development – Mutant mice • Effects of experience on development – Occular dominance • Developmental disorders – Fragile X, Down, Autism Spectrum • Aging Stages of Neural Development 1. Neurogenesis – mitosis produces neurons 2. Cell migration – cells move to establish distinct populations 3. Differentiation – cells become distinctive neurons or glial cells Stages of Neural Development 4. Synaptogenesis – establishment of synaptic connections 5. Neuronal cell death – selective death of some nerve cells 6. Synapse rearrangement – loss or development of synapses, fine-tuning Neurogenesis • New neurons and glial cells are formed in a part of the neural tube called the ventricular zone • Neurons themselves do not divide (but they are a product of cell division)
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2 Cell Migration • During cell migration cells move away from the ventricular layer. • Radial glial cells act as guides for cells to migrate along. Figure 7.6 Glial Spokes Guide Migrating Cells (Part 1) Cell migration Gonadotropin Releasing Hormone • Gonadotropin releasing hormone (GnRH) – In females, GnRH is the master regulator of estrogen and progesterone secretion from ovaries – Activity of GnRH producing neurons controls menstrual cycles and fertility – In males, GnRH is the master regulator of testosterone secretion in testes and influences sperm production GnRH Neuron Migration Kallmann’s syndrome • Men with Kallmann’s syndrome develop without an olfactory bulb – Anosmic: can not smell • Coincides with small testes and infertility
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Cell Differentiation When cells reach their destinations they begin to express genes to make the proteins they need. This cell differentiation allows a cell to acquire its specific appearance and function. Cell Differentiation Two classes of influences on differentiation: Cell-autonomous – independent of other cells and driven by genes, intrinsic organization as seen in vitro • Neural environment – differentiation affected by other cells Sonic hedgehog • Sonic hedgehog is a gene that regulates cell differentiation • It’s not the presence or absence of sonic hedgehog that influences cell differentiation, but the relative concentration Sonic Hedgehog Gradient • Sonic hedgehog is produced in the base of the embryo, concentration decreases with distance – High concentration = motor neuron (MN) – Low concentration = interneuron (V1 or V2) Neuronal floor plate: FP Synaptogenesis Both axons and dendrites grow extensively, forming many synapses This process is guided by chemicals released by the target cells. Chemoattractants:
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This note was uploaded on 11/08/2010 for the course PSC Psychology taught by Professor Cossowings during the Spring '08 term at UC Davis.

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Class4_Development - Outline Development Stages of neural development Effects of genetics on development Mutant mice Effects of experience on

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