1. Spectral sensitivity of cones
“Blue”
cones
“Green”
cones
“Red”
cones
˙ Three types of opsins
˙ Color blindness is
caused by lack of one
or more cone types
Relateive response
Wavelength (nm)
Figure by MIT OCW. After figure 9.20 in: Bear, Mark F., Barry W. Connors, and Michael A.
Paradiso. Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams &
Wilkins, ISBN:

2. Color space is 3d ˙ Any color can be synthesized by mixing
three primary colors.
˙ Young-Helmholtz
trichromacy theory
Image removed due to copyright reasons. Please see figure 9-21 in: Bear, Mark F., Barry W.
Connors, and Michael A. Paradiso. Neuroscience: Exploring Brain. 2nd ed. Baltimore, Md.:
Lippincott Williams & Wilkins, ISBN:

3. Retinal ganglion cells
Output cells of the retina
Send a million axons in the optic nerve
Background rate of spiking
Rate of spiking is modulated up or down
by visual stimulation

4. Visual neurophysiology
Anesthetized cat
Video: visual stimulus seen by cat
Audio: extracellular recording

5. Receptive field
The area of retina (or of visual space) in which a stimulus can cause changes in the activity of a neuron.
The “preferred stimulus” is that which causes the most increase in rate of action potential firing.

6. Center-surround antagonism
OFF-center ganglion
Cell output:
Ganglion cell
Receptive field
Patch of
retina
Center
Surround
Dark spot
Figure by MIT OCW. After figures 9.23 a, b, and c in: Bear, Mark F., Barry W. Connors, and Michael
A. Paradiso. Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams &
Wilkins, ISBN:

7. Visual stimuli Moving spot Flashed spot Annulus
Spot with changing ciameter
Moving bar

8. Transient vs. sustained
M-type
Ganglion cell
(ON center)
P-type
Ganglion cell
(ON center)
Light in
receptive
field center ON
OFF
Action
potentials
per second
note: offset of visual stimulus can
lead to suppression of spiking below
background rate (not shown here)
Figure by MIT OCW. A fter figure 9.27 in: B ear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

9. P and M ganglion cells ˙ Smaller P-type (90%) ˙ Larger M-type (5%)
˙ Sustained
˙ Stimulus form
˙ Color-opponent
˙ Larger M-type (5%)
˙ Transient
˙ Stimulus movement
Figure by MIT OCW. After figure 9.26 in: Bear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

10. Color aftereffect ˙ Psychological evidence of red-green
and blue-yellow
opponency
˙ Hering’s opponent
process theory
Figure by MIT OCW. After figure 9.29 in: Bear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

11. Neural basis of color opponency
Images removed due to copyright reasons. Please see figure 9.28 in: Bear, Mark F., Barry W.
Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.:
Lippincott Williams & Wilkins, ISBN:

12. Dual process theory Resolution of the debate with a hybrid theory
Photoreceptors
- Young-Helmholtz trichromacy
Ganglion cells
- Hering color opponency
Further reading: S.E. Palmer, Vision Science, MIT Press (1999).

13. Sensitivity to spatial differences
Four categories of OFF-center ganglion cells responding to an edge
Ganglion cell
Receptive field
OFF-center ganglion
Cell output:
Patch of
retina
Center
Surround
Responses of cells near the edge a
exaggerated contrast-enhancement
Dark spot
Figure by MIT OCW. After figure 9.24 in: Bear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

14. Simultaneous contrast illusion
Figure by MIT OCW. After figure 9.25 in: Bear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

15. Mach and Chevreul

16. Lateral inhibition Horizontal cells Amacrine cells
Images removed due to copyright reasons. Please see figures 9.22 a, b, and c in: Bear,
Mark F., Barry W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the
Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, ISBN:

17. Convolution Mathematical idealization of retinal computation
Image removed due to copyright reasons.

18. Engineering applications
Silicon retinas
- Kwabena Boahen (U penn)
Retinal prosthetics
- John Wyatt (MIT)

19. Central visual system

20. Retinofugal projection
Eye
Optic Nerve
Optic Chiasm
Stalk of Pituitary Gland
Optic Tract
Cut Surface of Brain Stem
Figure by MIT OCW. After figure 10.2 in: Bear, Mark F., Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.: Lippincott Williams & Wilkins, 2001.
ISBN:

21. Right and left visual hemifields
Binocular Visual Field
Fixation Point
Right Visual Hemifield
Left Visual Hemifield
Right Eye
Right Optic Nerve
Left Eye
Right Optic Tract
Left Optic Nerve
Left Optic Tract
Optic Chiasm
˙ The left visual
hemifield is “viewed”
by the right
hemisphere, and vice
versa.
Figure by MIT OCW. After figure 10.3 in: Bear, Mark F.,
Barry W. Connors, and Michael A. Paradiso.
Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.:
Lippincott Williams & Wilkins, ISBN:

22. Retinogeniculocortical pathway
Retina LGN V1
pathway for conscious
visual perception
Images removed due to copyright reasons. Please see figures 10.4 a and b in: Bear, Mark F., Barry
W. Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.:
Lippincott Williams & Wilkins, ISBN:

23. Lateral geniculate nucleus
˙ dorsal thalamus
˙ major targets of optic
tracts
Images removed due to copyright reasons. Please see figure 10.8 in: Bear, Mark F., Barry W.
Connors, and Michael A. Paradiso. Neuroscience: Exploring the Brain. 2nd ed. Baltimore, Md.:
Lippincott Williams & Wilkins, ISBN:

24. Retinotopy Neighboring retinal cells project to neighboring LGN cells.
There are maps of visual space in the LGN.
Magnification of map for central vision.

25. LGN input is segregated
Left LGN
Right LGN
Left Temporal
Retina
Left Nasal
Retina
Right Temporal
Retina
Right Nasal
Retina
˙ contra: layers 1,4,6
˙ ipsi: layers 2,3,5
˙ retinotopic map in
each layer
˙ maps are aligned
Figure by MIT OCW. After figure 10.9 in: Bear,
Mark F., Barry W. Connors, and Michael A.
Paradiso. Neuroscience: Exploring the Brain.
2nd ed. Baltimore, Md.: Lippincott Williams &
Wilkins, ISBN:

26. LGN function?? Receptive fields like retinal ganglion cells
80% of excitatory synapses from conrtex
Neuromodulatory input
- alertness
- attention
- sleep