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Before We Continue

Before We Continue. Lets Recap!. Identify the gray matter and white matter. B. A. C. D. The Brain. A. E. F. B. G. H. I. J. K. SfN’s Brain Facts. The Brain. SfN’s Brain Facts. Review. Dendrite. Greek for branches of a tree. The three components of a neuron are …

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Before We Continue

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  1. Before We Continue Lets Recap!

  2. Identify the gray matter and white matter. B A

  3. C D The Brain A E F B G H I J K SfN’s Brain Facts

  4. The Brain SfN’s Brain Facts

  5. Review Dendrite • Greek for branches of a tree. • The three components of a neuron are … • The functional cell that allows us to think, act, & learn. • Name for the electrical impulses neurons use to send messages, • The net charge of a neuron at rest. • Proteins embedded into the cell membrane that allow for ions to move into or out of cells. • Type of ions that depolarize the cell. • How many neurons does the brain have? • Name a device that measures brain waves. • A neuron releases Neurotransmitters into a synapse with another axon. Assuming, this will pass stimulate to the next neuron, explain how the signal will be sent. Dendrite, cell body & axon neuron Action potential negative Protein channels positive 100 billion electroencephalograph

  6. 1)The Neuron receives a signal at its dendrites. • (2) This signal travels and opens specific ion channels in the axon that allow positive ions inside the cell. • (3)Ion channels open sequentially, with the first open ion channels at the axon hillock, or base of the axon. • 4)The Action Potential travels down the axon extremely fast, at speeds up to several hundred miles per hour. • (5)Once the action potential reaches the end of the axon, it causes the release of neurotransmitters out of the neuron at the nerve terminal. • The neurotransmitters diffuse a short distance and bind specific receptors on the surface of a second neuron where it will either stimulate or inhibit it from generating another action potential.

  7. More Review Hypothalamus • The biological clock is located in what part of the brain? • True or False: The Cerebellum is crucial for motor learning. • What Brain Region processes Fear and anxiety? • Name the primary drug used to treat Parkinson’s Disease. • To the Nearest pound, what is the weight of the human brain? • The abbreviation PET stands for what brain imaging technique? • Nitric oxide is the major regulator of what intracellular messenger molecule? • Name the contact points where one neuron communicates with another. true amygdala L Dopa 3 lbs Positron emission topography Cyclic GMP (cyclic guonosinemonophosphate Synapse

  8. More Questions Acetylcholine • Excitatory Neurotransmitter who, when unable to bind to muscle receptors, causes myasthenia gravis. • Name the part of the brain that is important for emotional learning and memory and its dysfunction is related to anxiety disorders. • What part of the brain helps control movement and cognitive processes that require precise timing? • Which lobe of the cerebral cortex processes visual information? • The Greek word meaning to “clasp together” gives us what neuroscience term? • Name the deep brain regions responsible for relaying and filtering sensory information. • Name the large bundle of nerve fibers linking the left and right cerebral hemispheres. Amygdala Cerebellum Occipital Synapse Thalamus Corpus Callosum

  9. Limbic System Androgens • The amygdala and septum are part of this group of brain structures that regulate emotion. • Name the hormones, which include testosterone, that are important for male sexual development. • Which branch of the autonomic nervous system mobilizes energy and resources during times of stress and arousal? • This region of the brain, located in the frontal lobe of the left hemisphere, is important for the production of speech. • This liquid is found within the ventricles of the brain and the central canal of the spinal cord. • What is the name of the class of neurotransmitters that are chains of amino acids? • Benzodiazepines (Valium) is used to increase the activity of this NT in the treatment of Huntington’s Disease. • Glutamate & Asparate are both amino acid NTs though to be involved in this important function (like right now). Sympathetic Brocca’s Cereborspinal Fluid Peptides GABA Learning & Memory

  10. Dopamine Norepinephrine • A lack of this NT can be supplemented with L-Dopa in the treatment of Parkinson’s. • An excitatory chatcolamine NT involved in the fight or flight response. Regulates Heart rate and blood pressure. • NT involved in OCD and Depression. • Name a difference between neurotransmitters and hormones in regard to their effective range. • Which region in the brain secretes endocrine hormones? Serotinin NT-Short distance Hormone-long distance Hypothalamus

  11. Brain Development (Brain Facts pages, 13-17)

  12. Why is it important to understand development?

  13. Background Knowledge (not in Brain Facts) Review on basic Development • Lets start at the beginning, a zygote is formed. • The zygote must go through cell division

  14. Embryo Developement • Sperm fertilizesegg & forms a zygote

  15. Zygote: Fertilized Egg • Zygote undergoes cleavage: a series of rapid cell divisions that results in the formation of many cells.

  16. Zygote Blastula Cleavage • A ball of cells forms with a fluid-filled center. This hollow ball of cells is called a Blastula.

  17. Zygote Blastula Cleavage

  18. Blastula Gastrula Gastrulation • Gastrulation occurs when a blastula, made up of one layer, folds inward and enlarges to create a gastrula.

  19. The 3 layers of the GASTRULA: • Ectoderm (outer): • Skin, sensory organs, nerves • Mesoderm (middle) • Muscles, circulatory, reproductive, excretory systems • Endoderm (inner): • Digestive tract, respiratory system

  20. 1.)The Journey of Nerve Cells Origins of the Nervous System Review • The neural plate forms from which embryonic cell layer? • About how long after conception does the neural plate form? • When the neural plate sides rise, fold towards each other, and close, the is__________ formed. • By 4 weeks, the top (anterior) of the tube thickens into 3 bulges that form the ______, _______, & _______. ectoderm About 3-4 weeks neural tube hindbrain midbrain forebrain

  21. General Brain Development 1. The appropriate number of neurons migrate to their appropriate places. 2. Axons and dendrites form connections. 3. Axonsrecognize a target cell. 4. Connectionsmature and change with different activity/experiences.

  22. Chapter Outline: 1a.) The Journey of Nerve Cells –Proliferation/Induction 1b.) The Journey of Nerve Cells – Migration 1c.) The Journey of Nerve Cells – Maturation/Making Connections 2.) Paring back/Selective Elimination 3.) Critical periods & Plasticity

  23. 1.)The Journey of Nerve Cells Origins of the Nervous System Induction • What is the process by which a single cell line becomes many different, specialized cells? • How can this process occur in the germ layers when they all possess the same genes? Differentiation Cellular signals from the mesoderm layer turn genes on and off.

  24. 1.)The Journey of Nerve Cells Origins of the Nervous System Induction • Molecules released from the mesoderm can trigger cells from which layer to become nervous tissue? • Specifically, what is the process called? • What happens to the majority of ________ cells that do not receive the mesoderm signal molecules. ectoderm Neural induction ectoderm They become skin

  25. 1.)The Journey of Nerve Cells Origins of the Nervous System Remember the three germ layers? • Ectoderm • Mesoderm • Endoderm Of these three, which will develop into both the nervous system and skin cells? Skinandneural tissue arise from one layer, the ectoderm, in response to signals provided by the adjacent layer, the mesoderm.

  26. Inhibitory control may direct neural development. • Many molecules interact to determine whether the ectoderm becomes neural tissue or develops into skin. • Studies in frogs show that one major mechanism depends on specific proteins that inhibit the activity of other proteins. • In areas where no inhibition occurs, the tissue becomes skin. • In areas where proteins secreted from the mesoderm do lead to inhibition, the tissue becomes neural.

  27. 1.)The Journey of Nerve Cells Origins of the Nervous System No Inhibition Ectoderm SKIN

  28. 1.)The Journey of Nerve Cells Origins of the Nervous System Inhibition from Mesoderm Proteins Ectoderm SKIN Nervous Tissue

  29. 1.)The Journey of Nerve Cells Origins of the Nervous System Neuron or Glial cell? • Once the ectoderm is destined to become neural tissue, it has two possibilities • Neuron: Signaling Cell • Glial Cell: Neuron Support Cell • depends on its • Cellular interactions • Position • Environmental cues

  30. 1.)The Journey of Nerve Cells Origins of the Nervous System SONIC HEDGEHOG Protein • Example, a key factor in spinal cord development is a secreted protein called sonic hedgehog. • The protein, initially secreted from mesodermal tissue (lying beneath the developing spinal cord), marks adjacent (closest) neural cells to become a specializedclass of glialcells. • Cells farther away are exposed to lowerconcentrations of sonic hedgehog, and they become the motorneurons. • An even lowerconcentration promotes the formation of interneurons

  31. 1.)The Journey of Nerve Cells Origins of the Nervous System MESODERMAL TISSUE Sonic Hedgehog Protein Graded Effect GLIAL CELLS Motor Neurons Interneurons

  32. MIGRATION 3-4 Weeks after conception: • Once neural induction has occurred, the next step for new neurons migration • Ectodermstarts to thicken and buildupalong the middle. • Cells continue to divide, forming a flat neuralplate • Parallelridges form & rise across neural plate’s surface. • Within a few days, the ridgesfold in toward each other and fuse to form a hollow neural tube. • The top of the tube thickens into threebulges that form the hindbrain, the midbrain, and the forebrain. • At week7, the first signs of the eyes and the brain’shemispheresappear.

  33. 1.)The Journey of Nerve CellsOrigins of the Nervous System 3-4 • ______ weeks after conception, one of the germ layers (_________) of the human embryo starts to thicken and build up along the middle, forming the ____________ ectoderm Neural plate

  34. 1.)The Journey of Nerve CellsOrigins of the Nervous System • As this flat neural plate grows, ________________rise across its surface. • The ridges fold in toward each other and fuse to form the hollow ___________ (by day 28). Parallel ridges neural tube

  35. 1.)The Journey of Nerve CellsOrigins of the Nervous System • The top of the tube thickens into three bulges that form the __________, __________, and __________. hindbrain midbrain forebrain Video: Neural Tube Formation

  36. 1.)The Journey of Nerve CellsOrigins of the Nervous System BRAIN DEVELOPMENT. The human brain and nervous system begin to develop at about three weeks’ gestation with the closing of the neural tube (left image). By four weeks, major regions of the human brain can be recognized in primitive form, including the forebrain, midbrain, hindbrain, and optic vesicle (from which the eye develops). Irregular ridges, or convolutions, are clearly seen by six months. Brain Facts Page 10

  37. FIGURE 3.5 Brain Development. This schematic outline of brain development shows its relation to the ventricles. Views (a) and (c) show early development. Views (b) and (d) show later development. View (e) shows a lateral view of the left side of a semitransparent human brain with the brain stem “ghosted in.” The colors of all figures denote corresponding regions.

  38. 1.)The Journey of Nerve Cells Origins of the Nervous System Migration • As neurons are produced, they move from the neural tube’s ventricularzone, or inner surface, to near the border of the marginalzone, or outer surface. • After neurons stop dividing, they form an intermediatezonewhere they gradually accumulate as the brain develops.

  39. 1.)The Journey of Nerve Cells Origins of the Nervous System

  40. 1.)The Journey of Nerve Cells Origins of the Nervous System Brain Facts Page 11

  41. 1.)The Journey of Nerve Cells Origins of the Nervous System How do they know where to go? • Neuron migration requires multiple guidance mechanisms, including the recognition of the properpath and the ability to move longdistances. • 90 % of migration in humans, are glia, which project radiallyfrom the intermediatezoneto the cortex. • Glia are providing temporary scaffolding for ushering neurons to their destination.

  42. 1.)The Journey of Nerve Cells Origins of the Nervous System How do they know where to go? • This process of radial migration occurs in an “inside-out” manner; that is, the cells that arrive the earliest (the oldest ones) form the deepest layer of the cortex, whereas the late-arriving(the youngest) neurons form the outermost layer. • In another mode, inhibitory interneurons migrate tangentiallyacross the brain.

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