Visual Cortex!
Vision Science Lectures in Ophthalmology
Curtis Baker Receptive fields of retinal ganglion cells
Retinal ganglion cells are optimized
for detecting contrast:
•  Centre-surround antagonism:
–  results from the concentric
spatial arrangement of the ON
and OFF subregions
•  Consequence is that retinal
output sent to the brain by
ganglion cells is driven by light
contrast, i.e. differences in
luminance
Chaudhuri, Fig 9.14
retina-LGN-cortex
KSJ, Fig 27-4
V1 neurons: orientation selectivity
KSJ,
Fig 27-11
V1 neurons: direction selectivity
neurons as stimulus filters!
simple cell receptive field
wrong spatial frequency
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optimal grating
wrong orientation
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near and far cells
KSJ, Fig 28-14
ocular dominance columns
KSJ, Fig 27-16
Population responses: optical imaging
CCD Camera
Stimulus Generator
Illuminator
Data Collection and Analysis
Real-time Video
Processor
(courtesy of Chang’an Zhan)
orientation columns
KSJ, Fig 27-14
cytochrome compartments
KSJ, Fig 28-1
cytochrome oxidase blobs
KSJ, Fig 27-15
-  input from LGN koniocellular layers
-  in centers of ocular dominance columns
-  receptive fields: non-oriented, colour-opponent
Russo-Japanese war
Glickstein M “The discovery of the visual cortex”
Scientific American, pp 118-127, Sept 1988
retinotopic map in V1
KSJ, Fig 27-9
retinotopic maps from fMRI
Sereno et al, 1995
field sign maps
Sereno et al, 1995
extrastriate visual areas
larger receptive fields, less retinotopy
functional specializations
single units: Zeki, V4 vs MT/V5
brain imaging: stimuli that selectively activate
(e.g., motion/flicker -> MT/V5)
KSJ, Fig 25-9
lesion effects
experimental approach (Mishkin & Ungeleider):
primates: lesion brain areas, test perception
temporal cortex (ventral):
object recognition, memory (“what”)
parietal cortex (dorsal):
spatial localization (“where”)
KSJ, Fig 25-11
dorsal & ventral streams: many
extrastriate areas
KSJ, Fig 28-2
dorsal and ventral streams:
neurophysiology
KSJ, Fig 25-12
effects of damage!
striate cortex (V1) -> blindness
V2 -> "quadrant" blindness
other extrastriate areas -> selective losses, e.g.:
MT / V5 -> motion-blindness
FFA (fusiform face area) -> prosopagnosia
fusiform cortex ("colour area" ?) -> achromatopsia
References
Primary Reading:
Chaudhuri A (2011) Sensory Perception. Oxford: Oxford Press.
Chap. 10: The visual system: Cortical Processing and Object Perception
Kaufman PL, Alm A (Ed) (2003) Adler's Physiology of the Eye, 10th ed. St.Louis: Mosby.
Chap. 26: Overview of the Central Visual Pathways
Chap. 29: The Primary Visual Cortex
Chap. 30: Extrastriate Visual Cortex
Kandel, Schwartz, and Jessell , Principles of Neural Science (4th Ed.)
Chap.27: Central Visual Pathways
Chap.28: Perception of Motion, Depth, and Form
General references for further reading:
Bruce, V., Green, P.R., and Georgeson, M.A., Visual Perception - Physiology, Psychology, and Ecology, 4th ed,
Psychology Press, 2003. A well illustrated and modern view of vision, with excellent integration of
computational, neurophysiological and psychological approaches. Probably the best advanced textbook on vision.
Carpenter, R.H.S., Neurophysiology, Edward Arnold, 1984. This is a very well-written, though not
comprehensive, introduction to elementary aspects of neurophysiology, and has quite good chapters on sensory
physiology.
Wandell, B.A., Foundations of Vision, Sinauer Associates, 1995. A relatively up to date book, with an emphasis
on human psychophysics, but connecting to neurophysiology and computational approaches.
specific references:
Cowey, A., and Heywood, C.A. (1997). “Cerebral achromatopsia: Colour blindness despite wavelength
processing”, Trends in Cognitive Sciences 1:133-139.
Sereno, M.I., Dale, A.M., Reppas, J.B., Kwong, K.K., Belliveau, J.W., Brady, T.J., Rosen, B.R., and Tootell,
R.B.H. (1995). Science 268: 889-893
web sites:
http://neurovision.berkeley.edu/Demonstrations/VSOC/vsoc/vns/index.html VNS (Visual Neuron Simulator) - PC and Mac versions of program to simulate response of a V1 neuron
Viperlib - library of perceptual illusions, demos - http://viperlib.york.ac.uk/index.asp
http://www.mvr.mcgill.ca - home page of McGill Vision Research