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Introduction to Neuroscience

PS1000. Introduction to Neuroscience. Dr Claire Gibson School of Psychology, University of Leicester cg95@le.ac.uk. Functional Neuroanatomy – The Nervous System and Behaviour Development and Plasticity of the Nervous System. Development of the NS. 4 main stages Cell proliferation

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Introduction to Neuroscience

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  1. PS1000 Introduction to Neuroscience Dr Claire Gibson School of Psychology, University of Leicester cg95@le.ac.uk

  2. Functional Neuroanatomy – The Nervous System and Behaviour • Development and Plasticity of the Nervous System

  3. Development of the NS 4 main stages • Cell proliferation • Migration • Differentiation • Synaptogenesis • Neuronal cell death • Synapse rearrangement • Myelination ….more detailed 7 stages = PS2014/8

  4. 1. Cell Proliferation • 250,000 new cells per minute • Neurogenesis = production of new nerve cells • Proliferation occurs in the ventricular zone (cells then migrate to final destination) • Nerve cells themselves do not divide • The cells that produce neurons divide (via mitosis) and = layer of cells within the ventricular zone • Eventually some cells migrate away from ventricular zone and begin differentiating into either a neuron or glia cell.

  5. 1. Cell Proliferation – when is it complete? • Historical opinion - at birth. • But, the human brain weight increases following birth • simply due to growth in neuronal size, dendrite branching, increased myelin ??? • NO - Neurogenesis occurs even in adulthood • Neurogenesis is sensitive to experience • Learning enhances neurogenesis • Social isolation reduces neurogenesis

  6. 2. Migration • Newly formed neurones migrate from ventricular zone to their final destination • Radial glial cells • Failure in mechanisms of migration = behavioural disorders • Cell adhesion molecules (CAMs) • Promote the adhesion of developing elements of the NS • Guide migrating cells and growing axons

  7. 3. Differentiation • Cells reach their final destination – begin to express particular genes • These enable cells to take on characteristics of a particular neuronal type • PS2014/8

  8. 4. Synaptogenesis Cells undergo extensive growth of axons and dendrites = process outgrowth and proliferation of synapses (i.e. synaptogenesis) • Growth cones • Filapodia and lamellipodia – respond to the environment and pull the growth cone in a particular direction • Chemoattractants • Chemorepellants • Synaptogenesis occurs rapidly on dendrites and dendritic spines

  9. 5. Neuronal cell death • Normal part of development • PS2014/8

  10. 6. Synapse rearrangement • Not simply elimination • Involves loss of some and formation of others • Human cerebral cortex = net loss of synapses from late childhood until mid-adolescence • What determines which synapses are kept and which ones are lost? • Neural activity • Neurotrophic factor = a target-derived chemical that acts to ‘feed’ neurones

  11. Development of the NS • Due to the interaction of intrinsic and extrinsic factors • Intrinsic (i.e. genes) – originate from within the cell itself • Extrinsic – originate from outside the developing cell e.g. nutrients, experience

  12. Genes are the intrinsic factors that influence NS development • Genome (genotype) • The sum of all the intrinsic genetic information that an individual possesses • Determined at the moment of fertilisation • Remains constant throughout our lives • Phenotype • The sum of all the physical characteristics that make up an individual • Changes constantly as we mature and age • Determined by the interaction of genotype and extrinsic factors (including experience)

  13. So, will two identical twins with identical genotypes • Have the same phenotype? YES/NO • Behave exactly the same? YES/NO

  14. How does experience modify the NS? • An individual’s experience during development alters many aspects of behaviour, brain anatomy and neurochemistry • Much of the change resulting from experience involves reorganisation • Reorganisation = a shift in connections that changes the function of an area of the brain • E.g. blind people who read Braille, space in the brain devoted to the index finger increases • E.g blind people who excel at sound localisation have recruited the unused visual area of their brain to aid in sound localisation

  15. The ‘plastic’ brain • So, if experience can ‘reorganise’ the brain = the brain is described as being plastic • Plasticity = the lifelong ability of the brain to reorganise neural pathways based on new experiences • Why is this important? • To enable us to learn • As an adaptive mechanism to compensate for lost function and/or to maximize remaining functions in the event of brain injury.

  16. Damage and recovery to the CNS • Scientists are interested in the development of the NS • Hope to find clues about how to repair the NS when it is damaged by injury, disease or developmental error • PS2014/8

  17. Summary • Neurogenesis, migration, differentiation, synaptogenesis, neuronal death, synapse rearrangement, myelination • Intrinsic and extrinsic factors • Role of experience

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