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Biology of Vision Lecture #1

Biology of Vision Lecture #1. 1/24/13. Today. Introductions History of vision studies Diversity of visual systems Brainstorming - what should we cover? Learning styles. Karen Carleton. Email : kcarleto@umd.edu Phone: 301-405-6929 Office: 2130 Biosciences Research Bldg

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Biology of Vision Lecture #1

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  1. Biology of Vision Lecture #1 1/24/13

  2. Today • Introductions • History of vision studies • Diversity of visual systems • Brainstorming - what should we cover? • Learning styles

  3. Karen Carleton • Email : kcarleto@umd.edu • Phone: 301-405-6929 • Office: 2130 Biosciences Research Bldg • 2nd floor - don’t need key card during day • Office hours – Tues 2-4 or by appointment

  4. Lab research

  5. Teaching is like tapping Sir Ken Robinson If the teacher does a lousy job:

  6. Sometimes teaching is humming If the teacher does a good job, some students will hear:

  7. But what the teacher is trying to say:

  8. Patrick Creighton • Our class Learning Assistant • Goal – to improve learning through class activities

  9. Class philosophy • Learning is a collaborative activity • Active process • Learning goes both ways • Teaching is learning and learning is teaching • Communication is key • Ask questions • Send email

  10. Comparative approach • Comparing the diversity of eyes throughout the animal kingdom • We can find out: • How eyes evolve - primitive to complex • What makes a good eye • How environment shapes vision • How tasks shape vision

  11. Textbook • Land and Nilsson “Animal Eyes” • Eye design and optics • If you have 1st edition, probably OK • Will cover topics for first half of class

  12. Other interesting texts that I will draw from (NOT required)

  13. Some of the course topics • Light and the environment • Visual pigments • Eye structures (optics) • Molecular signal transduction • Eye disease • Neural processing • Development and evolution

  14. Assessments • Class participation 10% • Homework 50% • Class wiki - Biology of vision • Midterm 20% • Final 20%

  15. Class on Canvas Links to website Grades

  16. 1st homework due by Monday at 11 pm Class website

  17. Questions ??? ??? Clickers????

  18. Visual science is integrative Biology Chemistry Psychology Art Physics Evolution Development

  19. Vision through history • Vision is key sense • - Always of interest • Focus of early science • How do humans see? • What parts of the eye detect light

  20. Ancient views • Intromission • Objects modify their surroundings sending information to the eye • Object pushes on air which carries info to eye (Democritus 460-370 BC) • Particles from object travel to eye (Epicurus 300 BC) • Extromission • Eyes produce light which bounces off object and • -create fiery particles which we see (Plato 400 BC) • -closer objects will be brighter (Euclid 300 BC)

  21. Ancient views • Aristotle (384-322 BC) • Eyes don’t produce light • We can’t see in the dark • Only luminous objects produce light • Fire, sun • Sunlight bounces off objects and comes to our eyes

  22. Galen’s anatomy: 133-200 AD • Defined many of key structures of eye • Retina • Aqueous/vitreous humor • Lens • Choroid • Believed psychic pneuma sent down optic nerve to connect eye to soul

  23. Alhazen 965-1040 AD • Worked out eye optics • Sun bounces off objects  Light comes to eye • Book of Optics vol I was translated - studied by Kepler • Vols II and III • Not translated • Key understanding of perception including color constancy, binocular vision

  24. Leonardo Da Vinci (1452-1519) • Discovered workings of camera obscura • Image passes through pinhole • Keeps all in focus • Inverts the image • Basis for how pupil functions

  25. Kepler (1571-1630) Identified functional elements • Lens • Retina • Muscles Inverted image forms on retina http://www.lumen.nu/rekveld/wp/?p=352

  26. Isaac Newton (1643-1727)’s understanding of color • White light is composed of all colors of rainbow • Objects reflect these different colors

  27. Thomas Young (1773-1829) • Lens accommodation • Color vision • Three kinds of nerve fibers

  28. Santiago Ramon y Cajal (1852-1934) • Retinal anatomy by staining neurons to describe all major cell types Drawing of retinal cell types

  29. How common are eyes? • 1/3 animal phyla have no eyes • 1/3 have light sensitive organs • 1/3 have eyes

  30. What is an eye? • Is this an eye? • Can distinguish light from different directions Fig 1.4

  31. Eye = Detects light with spatial resolution • Multiple receptors in pigment cup • Sensitive to multiple directions • Create “image” of surroundings Fig 1.3

  32. Eyes evolve Origin of eyes • Life began 3.5 billion years ago • Eyes arose only 0.5 billion years ago

  33. What caused eyes to evolve? • Animals got larger • Larger eyes could better resolve surroundings • Predators move faster • Arms race that caused morphological evolution of prey http://www-eaps.mit.edu/geobiology/research/images/burgess.jpg

  34. Trilobites had compound eyes http://www.trilobites.info/eyes.htm

  35. Earliest vertebrate with eye • Arose about 25 MY after Cambrian explosion • Conodont were eel like - now extinct • Named for their teeth • Large single chambered eye

  36. Oldest extant vertebrate with eye • Lamprey • Raised in streams • Live in ocean • Return to streams to spawn • Has sophisticated eye

  37. One way to increase eye resolution • Add more receptors and take advantage of common light collection and shielding • Single chambered eye

  38. Another way to increase eye resolution • Multiply visual organ many times • Compound eye

  39. How many eye designs? a pit b compound c lens d cornea e apposition f superposition g single chamber mirror h compound mirror

  40. Brainstorming Break • What do you want to be sure to learn about this semester?

  41. HW#1 part 2: Maryland Biology Expectation Survey • To help us teach better • Try to understand students attitudes about learning • Take this survey at beginning and end of semester • Worth 5 pts extra on HW grade

  42. Give them name and email – they will send link to survey This is how we know who participates but it keeps your name separate from your answers - anonymous

  43. HW#1 part 1: Learning styles • Everyone learns using multiple approaches • Several different axes which describe how we learn • Richard Felder, NCSU • Each style is on a continuum

  44. 4 axes • Active - Reflective • Sensitive - Intuitive • Visual - Verbal • Sequential - Global

  45. Caveats • No style is “right” or “wrong” • Each has strengths and weaknesses • No one is one or the other • You can be one side sometimes and on the other side other times • Best if can be on both sides

  46. Active vs Reflective

  47. Ways to help • Active • Study in a group where lots of discussion • Try work problems to see how ideas work • Do something with new info • Reflective • Don’t just read - stop and think • Write short summaries • Think about new info

  48. Sensors vs Intuitors

  49. Ways to help • Sensing • Connect info to real world • Find specific examples of ideas and how they apply in practice • Intuitive • For fact based classes, find interpretations and theories that link facts • Connect things to yourself • Take time to read questions before hurrying to answer (compensate for impatience with detail)

  50. Visual vs Verbal More students are visual I will try to present as much visual information as possible

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