Biology of Vision Biology of Vision Lecture #1 Lecture #1 1/24/13
Jan 06, 2016
Biology of Vision Biology of Vision Lecture #1 Lecture #1
1/24/13
TodayToday
• Introductions• History of vision studies• Diversity of visual systems• Brainstorming - what should we
cover?• Learning styles
Karen CarletonKaren Carleton
• Email : [email protected]• Phone: 301-405-6929• Office: 2130 Biosciences Research
Bldg2nd floor - don’t need key card during
dayOffice hours – Tues 2-4 or by
appointment
Lab researchLab research
Teaching is like tappingTeaching is like tapping
If the teacher does a lousy job:
Sir Ken Robinson
Sometimes teaching is hummingSometimes teaching is humming
If the teacher does a good job, some students will hear:
But what the teacher is trying to But what the teacher is trying to say:say:
Patrick CreightonPatrick Creighton
• Our class Learning Assistant
• Goal – to improve learning through class activities
Class philosophyClass philosophy
• Learning is a collaborative activityActive process
• Learning goes both waysTeaching is learning and learning is
teaching
• Communication is keyAsk questionsSend email
Comparative approachComparative approach
• Comparing the diversity of eyes throughout the animal kingdom
• We can find out:How eyes evolve - primitive to complexWhat makes a good eyeHow environment shapes visionHow tasks shape vision
TextbookTextbook
• Land and Nilsson “Animal Eyes”Eye design and optics
• If you have 1st edition, probably OKWill cover topics for first half of class
Other interesting texts that I Other interesting texts that I will draw from (NOT required)will draw from (NOT required)
Some of the course topicsSome of the course topics
• Light and the environment• Visual pigments• Eye structures (optics)• Molecular signal transduction• Eye disease• Neural processing• Development and evolution
AssessmentsAssessments
• Class participation 10%• Homework 50%
Class wiki - Biology of vision
• Midterm 20%• Final 20%
Class on CanvasClass on Canvas
Links to website Grades
Class Class websitewebsite
1st homework due by Monday at 11 pm
QuestionsQuestions
Clickers????
Visual science is integrativeVisual science is integrative
Evolution
Psychology
Biology
Chemistry
Physics
Development
Art
Vision through historyVision through history
• Vision is key sense - Always of interest
• Focus of early science- How do humans
see?- What parts of the
eye detect light
Ancient viewsAncient views
• IntromissionObjects modify their surroundings sending
information to the eyeObject pushes on air which carries info to eye (Democritus 460-370 BC)Particles from object travel to eye (Epicurus 300 BC)
• ExtromissionEyes produce light which bounces off object and
-create fiery particles which we see (Plato 400 BC)-closer objects will be brighter (Euclid 300 BC)
Ancient viewsAncient views
• Aristotle (384-322 BC)Eyes don’t produce light
We can’t see in the darkOnly luminous objects produce light
Fire, sun
Sunlight bounces off objects and comes to our eyes
GalenGalen’’s anatomy: 133-200 ADs anatomy: 133-200 AD
• Defined many of key structures of eyeRetinaAqueous/vitreous humorLensChoroid
• Believed psychic pneuma sent down optic nerve to connect eye to soul
Alhazen 965-1040 ADAlhazen 965-1040 AD
• Worked out eye optics Sun bounces off objects Light comes to eyeBook of Optics vol I was translated - studied by Kepler• Vols II and IIINot translatedKey understanding of perception including color constancy, binocular vision
Leonardo Da Vinci (1452-1519)Leonardo Da Vinci (1452-1519)
• Discovered workings of camera obscuraImage passes through pinholeKeeps all in focusInverts the image
• Basis for how pupil functions
Kepler (1571-1630)Kepler (1571-1630)
Identified functional elementsLensRetinaMuscles
Inverted image forms on retina
http://www.lumen.nu/rekveld/wp/?p=352
Isaac Newton (1643-1727)Isaac Newton (1643-1727)’’s s understanding of colorunderstanding of color
• White light is composed of all colors of rainbow• Objects reflect these different colors
Thomas Young (1773-1829) Thomas Young (1773-1829)
• Lens accommodation
• Color visionThree kinds of nerve fibers
Santiago Ramon y Cajal (1852-Santiago Ramon y Cajal (1852-1934)1934)
• Retinal anatomy by staining neurons to describe all major cell types
Drawing of retinal cell types
How common are eyes?How common are eyes?
• 1/3 animal phyla have no eyes
• 1/3 have light sensitive organs
• 1/3 have eyes
What is an eye?What is an eye?
• Is this an eye?
• Can distinguish light from different directions
Fig 1.4
Eye = Detects light with spatial Eye = Detects light with spatial resolutionresolution
• Multiple receptors in pigment cup
• Sensitive to multiple directions
• Create “image” of surroundings
Fig 1.3
Origin of eyesOrigin of eyes
• Life began 3.5 billion years ago
• Eyes arose only 0.5 billion years ago
Eyes evolve
What caused eyes to evolve?What caused eyes to evolve?
• Animals got largerLarger 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
Trilobites had compound eyesTrilobites had compound eyes
http://www.trilobites.info/eyes.htm
Earliest vertebrate with eyeEarliest vertebrate with eye
• Arose about 25 MY after Cambrian explosion
• Conodont were eel like - now extinctNamed for their teethLarge single chambered eye
Oldest extant vertebrate with Oldest extant vertebrate with eyeeye
• LampreyRaised in streamsLive in oceanReturn to streams to spawn
• Has sophisticated eye
One way to increase eye One way to increase eye resolutionresolution
• Add more receptors and take advantage of common light collection and shieldingSingle chambered eye
Another way to increase eye Another way to increase eye resolutionresolution
• Multiply visual organ many timesCompound eye
How many eye designs?How many eye designs?
a pitb compoundc lensd corneae appositionf superpositiong single chamber mirrorh compound mirror
Brainstorming BreakBrainstorming Break
• What do you want to be sure to learn about this semester?
HW#1 part 2: Maryland HW#1 part 2: Maryland Biology Expectation SurveyBiology Expectation Survey
• To help us teach better• Try to understand students
attitudes about learning• Take this survey at beginning and
end of semesterWorth 5 pts extra on HW grade
Give them name and email – Give them name and email – they will send link to surveythey will send link to survey
This is how we know who participates but it keeps your name separate from your answers - anonymous
HW#1 part 1: Learning stylesHW#1 part 1: Learning styles
• Everyone learns using multiple approaches
• Several different axes which describe how we learn
• Richard Felder, NCSUEach style is on a continuum
4 axes4 axes
• Active - Reflective• Sensitive - Intuitive• Visual - Verbal• Sequential - Global
CaveatsCaveats
• No style is “right” or “wrong”Each has strengths and weaknesses
• No one is one or the otherYou can be one side sometimes
and on the other side other times
Best if can be on both sides
Active Active vs vs Reflective Reflective
Learn by doing something active with new info - discuss, apply or explain
Learn by thinking quietly about new info
“Let’s try it out and see how it works”
“Let’s think it through first”
Like group work Like to work alone
Ways to helpWays to help
• ActiveStudy in a group where lots of discussionTry work problems to see how ideas workDo something with new info
• ReflectiveDon’t just read - stop and thinkWrite short summariesThink about new info
Sensors Sensors vs vs Intuitors Intuitors
Like learning facts Discover possibilities and relationships
Solve problems with well established methods - don’t like surprises
Like innovation - don’t like repetition
Patient with details, good at memorizing facts and hands-on work (lab work)
Good at grasping new concepts, abstract ideas
Practical and careful Work faster and more innovatively
Want connection to real world
Don’t like plug and chug and rote memorization
Ways to helpWays to help
• SensingConnect info to real worldFind 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 yourselfTake time to read questions before
hurrying to answer (compensate for impatience with detail)
Visual Visual vs vs Verbal Verbal
Like to see pictures, diagrams, flow charts, timelines, demonstrations
Like written or spoken explanations
More students are visual
I will try to present as much visual information as possible
Ways to helpWays to help
• VisualFind other ways to present or
summarize materialThink about concept maps linking key
pointsColor code notes with highlighters
• VerbalWrite summaries or outlines of materialWork in a group where you can explain
info to each other
Sequential Sequential vsvs Global Global
Learn in linear steps, each following the last
Learn in large jumps, gather material and then suddenly “get it”
Follow logical thinking Solve problems in novel ways once grasp big picture - not always sure how solved it
Ways to helpWays to help
• SequentialMost courses taught sequentially. If prof skips
around, ask them to fill in steps or try to fill in yourself
Outline material in logical orderStrengthen global thinking by relate new topic to
other things you know
• GlobalGet the big picture first - how does it relate to
what you already knowSkim entire chapter and then go back to get
detailsWork on one thing at time till you get big picture
How do you prefer to gather How do you prefer to gather information?information?
• InductiveStart from facts and observations
Infer overarching principles
• DeductiveStart with principles
Infer consequences and applications
• Research suggests inductive learning is deeper and better retained
GoalsGoals
• To have you know more about how you learn
• For you to know how I learn / teach
• To make the course so we all learn better
Take ILS.
Enter results on the survey monkey by Monday night 11 pm
Sample resultsSample results
ACT X REF 11 9 7 5 3 1 1 3 5 7 9 11 <-- -->
SEN X INT 11 9 7 5 3 1 1 3 5 7 9 11 <-- -->
VIS X VRB 11 9 7 5 3 1 1 3 5 7 9 11 <-- -->
SEQ X GLO 11 9 7 5 3 1 1 3 5 7 9 11 <-- -->
Enter your results on Enter your results on anonymous survey monkey by anonymous survey monkey by
Monday 11 pmMonday 11 pm