Lecture6_revised

Lecture6_revised - Psychology 110: Biological Psychology...

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Psychology 110: Biological Psychology Lecture 6: Development and plasticity
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Recap of course so far we’ve seen how neurons generate electrical signals and how these electrical signals are transmitted through the nervous system we’ve explored the chemical component of neuronal transmission, the synapse. we’ve looked at some of the techniques available to study the workings of the nervous system. over the next couple of lectures we’re going to explore how the nervous system changes as we grow and learn.
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Cellular mechanisms of neuronal development 1. Neurogenesis The mitotic division of non-neuronal cells to produce neurons 2. Cell migration The movement of nerve cells or their precursors to establish distinct neuronal populations 3. Differentiation Cells become distinct types of neurons 4. Synaptogenesis The establishment of synaptic connections between axons and dendrites 5. Neuronal death The selective death of many neurons 6. Synapse rearrangement The refinement of synaptic connections
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Neurogenesis Cells of the inner layer of the neural tube divide to form a layer of cells called the ventricular zone. The cells continue to divide to form daughter cells. Eventually daughter cells leave this area and become neurons. Neurons themselves do not divide. ~22 days old
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Cell migration Early in development, radial ‘glial’ cells span the width of the emerging hemispheres. Glial cells constitute about half the cells in the brain. They act as ‘support cells’ to the neurons (literally in some cases!). Glial cells hold neurons in place, supply nutrients and chemicals, produce myelin and destroy and remove dead neurons.
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Cell migration Neurons creep from the inside to the outside of the nervous system (where they will form the cortex) using the glial cells like guide rails.
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Cell migration Time lapse photograph of a cerebellar neuron migrating up a glial cell. Cell migration occurs in six waves, each wave forming a successive layer of cortex.
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Differentiation Once the neuron reaches its final destination it begins to differentiate, by turning on (‘expressing’) certain genes, that lead to the building of specific proteins. This then leads to the neurons specific characteristics. This differentiation is dependent on both cell-autonomous processes (i.e. dependent on the individual cell only under the control of its own genes) and cell-cell interactions (i.e. dependent on the neuron’s environment).
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Cell-autonomous differentiation Cerebellar purkinje cells develop their characteristic dendritic trees even if they are grown isolated in glass dishes.
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Cell-cell interactions Notocord Ventral spinal cord Dorsal spinal cord The notocord releases a protein (called ‘sonic hedgehog’) that causes the nearby neurons (in the ventral spinal cord) to differentiate into motoneurons (indicated by gold color). Cell-cell interactions provide flexibility. For example, if a limb bud is
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This note was uploaded on 10/16/2010 for the course PSYCH 110 taught by Professor Staff during the Fall '08 term at Berkeley.

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Lecture6_revised - Psychology 110: Biological Psychology...

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