1. A.1 Neural Development IB Biology 2015-2016

3. The basics: The Nervous System https://www.youtube.com/watch?v=qPix_X-9t7E

4. Embryogenesis The study of the fertilized egg to a fully formed organism Typically done using animal models; same phylum as humans (Chordata, subphylum Vertebrates) –Fish, amphibians, reptiles, birds, mammals

5. What happens after fertilization? Three distinct tissues layers begin to form: LayerLocationEnd Result EctodermOutermost layerThe brain and nervous system MesodermMiddle layerThe skeletal, reproductive, circulatory, excretory, and muscular systems EndodermInner layerThe lining of the gut and other organs

6. You will need to annotate this diagram!

7. Neural Tube Formation From those layers, one of the first organs to develop is the neural tube –Will eventually become the brain and spinal cord – which is obviously SUPER IMPORTANT! As embryogenesis continues, the neural plate folds in, closes, and becomes a neural tube. This elongates and becomes the brain and spinal cord. http://media.pearsoncmg.com/intl/ema/9781447959007_BiolHL_Damon/Animations/ch12p496/index.htmlhttp://media.pearsoncmg.com/intl/ema/9781447959007_BiolHL_Damon/Animations/ch12p496/index.html

9. Neural tube formation A progressive process: does not take place simultaneously all along the body –The brain develops much sooner than the caudal (tail) end –What happens if the caudal end never fully closes? Spina Bifida Ciarlo's Story

10. Neurogenesis The neurones of the central nervous system (CNS) originate in the neural tube Neurogenesis is the process by which neuroblasts mature into neurones –Splits into two major types of cells: Glial Cells (support, nourish, protect neurones, among other things) Neurones (messengers)

12. Axon Growth As the neurone grows, it will send out one long axon moving towards it’s destination Unfavorable surface? Axon contracts Favorable surface? Axon persists forward An axon can move forward 1mm/day!

13. Axon Growth When an axon reaches it’s final destination, a synaptic connection must form with the target cell The target cell sends signals into the environment for the neurone to respond to One type of signal is a cell adhesion molecule (CAM)

14. Axon Growth- CAMs CAMs are located on the surface of cells The growth-cone of the axon has a CAM- specific receptor (like a lock and key) If they match, the chemical message takes place, activating enzymes to elongate the axon (growth and movement)

15. Voluntary muscle movement Mammalian motor neurones extend beyond the neural tube and out of the CNS (brain and spinal cord) –Can be up to 1m!!! Use same CAM process

16. Many, many synapses A single nerve makes many connections at first; needs to find best fit If the connection does not work or is not efficient, that connection will be eliminated This has mainly been studied with muscles and neurones from the spinal cord –The areas Where the connections persist are called neuromuscular junctions Neural Pruning –Children 2-3 years old have 15,000 synapses per neurone… TWICE as many as an adult brain!! –Neural Pruning eliminates simple childhood connections and allows them to be replaced with complex adult connections –Microglia – type of glial cells that prune unused connections Learning Language

17. Brain Plasticity: Your brain is PLASTIC

18. Functional vs. Structural Plasticity Functional Plasticity: the ability of the brain to move functions from a damaged area to an undamaged area

19. Functional vs. Structural Plasticity Structural Plasticity: the fact that the brain change it’s physical structure as a result of learning

20. What about a stroke? https://www.youtube.com /watch?v=wLw-7bvVQ1M

21. How to control someone else’s arm with your brain https://www.youtube.com/watch?v=rSQNi5sAwuc https://www.youtube.com/watch?v=_7_XH1CBzGw What is so special about the brain?

22. Practice