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 : kcarleto@umd.edu• 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