Animal vision nsta 102911

Animal vision presentation by Dr. Ishara Mills-Henry at NSTA-Hartford Oct. 29, 2011.

1. Through the eyes of an animal:
how animals see
Ishara Mills-Henry, Ph.D.
Science of the Eye Program
MIT

3. ????

7. What do animals see?

8. What do animals see?

9. The Retina
From www.howstuffworks.com
Retina

10. Retina
 Humans are considered trichromats
 Blue, Red, and Green Cone Photorecpetors
 Rod photoreceptors – are important for vision in dim light

11. Rods – Low light
Cones – Color vision
Three Main Parts:
a. Outer Segments
b. Cell body
c. Synaptic terminal

12. Visual Responses
•Optokinetic Response/Reflex
–Maintain image on retina stable
–Innate reflex
•Optomotor Response/Reflex
–Locomotive behavior
–Hypothesized to play a role in control of speed and direction of
body movement
–Innate reflex
•Escape or Avoidance Response
–Avert danger
–Innate reflex
Ability to test: Colors, Spatial frequency, and Motion detection

13. Observing our eye movements
•Umbrellas
•Groups of three
One person twists an umbrella
while the other tries to focus on
the umbrella without moving
their eyes.
The third person can observe.
The umbrella should have a pattern or make stripes on a solid
color umbrella with tape

14. Eye movements (microsaccades)
http://www.michaelbach.de/ot/mot_eyeJitter/index.html from Pinna B & Spillmann L (2002) A new illusion of floating motion in depth. Perception 31:1501–1502.
Involuntary eye movements – This illusion makes us aware of the small movements our eyes make. Our eyes
these movements even if we think we are focusing on an object. This is to prevent the photoreceptors in the
retina from desensitizing. If photoreceptors desensitize they will no longer pass the signal to the brain of the
object we are seeing. It would reduce the visibility of an object.

15. • Drum lined with black
and white stripes
• Light source
illuminates drum

16. Optokinetic Response
Vertebrates exhibit numerous reflex behaviors that are driven by visual stimuli. The
OKR response encompasses smooth eye rotations which track moving patterns followed
by sharp movements called saccades.

17. Optomotor Response
•Zebrafish (http://baierlab.ucsf.edu/omr.html)

18. Escape or Avoidance Response

19. Compound Eyes
•From http://universe-review.ca/R10-33-anatomy.htm
• Repetitive facets called ommatidia
• Image formation probably more of a
mosaic than individual images
•(But the glasses are still fun)

20. House crickets (Acheta domesticus)
•Omnivorous scavengers
•Feed on organic materials, as well as
decaying plant material, fungi, and
some seedling plants
•Active mostly at night
•Have UV (332 nm), blue (445 nm), and
green (515 nm)
•Habitat: Forest and grasslands
•See polarized light (navigation
purposes)
• Detect visual cues for
place memory

21. Phototaxis
•Movement towards or away from light

22. Drosophila
Habitat: rotting fruit
Phototaxis
Eight photoreceptors arranged in a
pattern
Vision: myopic/poor spatial quality but
able to detect movement quickly
Smaller lenses captures less light

23. Mealworms/Darkling Beetles
(tenebrio moliter)
•Over 20,000 species
•Larval stages are used as a food
source fish, reptiles, and birds.
•Adult darkling beetles – active
both day and night
•Habitat: burrows in grain
•Eat mostly vegetation – fresh and
decaying
•Spectral response – 520 nm and
334 – 365 nm (UV)
Do they exhibit negative or positive phototaxis?
Does the larval stage behavior differ from the adult stage?

24. Planaria
(Schmidtea mediterranea)
•Flatworms
•Usually used to study
regeneration
•Habitat: Under rocks in river beds
•Eye contains pigment and
photoreceptor cells

25. Emperor Scorpions (Pandinus imperator)
•Found in the tropical forests
and savannas of Africa
•Docile, although can become
territorial and cannibalistic
•Nocturnal –hunts for prey at
night
•Habitat: under rocks, logs, and
other forest debris

26. Scorpion Fluorescence
•Scorpions fluorescence under
UV light.
•Exoskeleton contains
compounds that exhibit
flourescence
•Recent studies suggested its for
detection and avoidance of the
UV light.
•Ability to discriminate between
species?
•Mating, navigation, ?)

27. More Interesting Information
Flight Simulator for flies?
May yield info for Robot Vision
http://www.youtube.com/watch?v=e5uPr_3SsHA&feature=player_embedded

28. What can animals with compound
eyes teach us?
Better Cameras and motion
detection systems?

29. Measuring Responses
• Place electrode on eye
• Light stimulus flashes
over the eye

30. Responses
Ganglion Cell Spike
Recordings
a = Hyperpolarization
of photoreceptors
b = On- Bipolar cells
depolarization
d = OFF-Bipolar cells
depolarization