Seminar topics 2008

 

Sign up for one of the seminars by sending an e-mail to a.stockman@ucl.ac.uk, giving also second and third choices.  Seminars will be assigned on a first-come, first-served basis. Note that the topic chosen must be distinctly different from the topic chose for the essay title. Topics already assigned are followed by the initials of the presenter.

 

Presentations should each be about 12 minutes in length.  Please time your presentations before you give them.  A data projector will be available in the room.  If you need any further help with references, please e-mail the seminar organizers.

 

 

 

Seminar 1. Retina seminar (TS)

A. What roles do opsins play in the initiation, and determination of the duration, of the light responses in rods and cones?
B. How are the center-surround receptive fields of the retina formed and what are their significance?
C. What do retinal amacrine cells do? HQ
D. What is light adaptation? Y
E. Why are there different classes of ganglion cell in the retina?
F. Discuss the evolution of colour vision.
G. How are distinct ON and OFF pathways generated and maintained in the retina?
H. How is the electroretinogram generated and recorded? Y

References:
General retina (everyone should be aware of the Web textbook): http://webvision.med.utah.edu
First steps in seeing. R. W Rodieck

Phototransduction references:
Leibrock, C. S. (1998). "Molecular basis of dark adaptation in rod photoreceptors." Eye 12: 511-520.
Pugh, E. N., S. Nikonov, and Lamb, T.D. (1999). "Molecular mechanisms of vertebrate photoreceptor light adaptation." Current Opinion on Neurobiology 9: 410-418.
Lamb, T. D. (1999). Photopigments and the biophysics of transduction in cone photoreceptors. Color vision: From Genes to Perception. K. Gegenfurtner and L. T. Sharpe. Cambridge, Cambridge University Press: 89-101.
Pugh, E. N. and T. D. Lamb (2000). Phototransduction in vertebrate rods and cones: molecular mechanisms of amplification, recovery and light adaptation. Handbook of biological physics, Vol. 3, Molecular mechanisms of visual transduction. D. G. Stavenga, W. J. de Grip and E. N. Pugh. Amsterdam, Elsevier: 183-255.
Arshavsky, V. Y., T. D. Lamb, and Pugh, E.N. (2000). "G proteins and phototransduction." Annual review of Physiology 64: 153-187.

 

Seminar 2. Psychophysics seminar (AS)

A. Compare and contrast the properties of rod and cone vision. Why do we need two systems? CvS
B. How do we see colour, and what are the limitations of our colour vision? LS
C. Describe the more common types of colour "blindness" and their causes. WLW
D. Show examples of visual illusions. For some of them, provide an explanation of what the illusion tells us about the visual system.
E. What do the psychophysical changes that occur with light adaptation tell us about how the visual system light adapts?
F. What monocular and binocular cues allow us to see depth? AR
G. Describe the mechanisms of light adaptation. SP
H. Show illusions of colour and explain what they tell us about colour vision.

References:
Rodieck, R. W. (1998). The First Steps in Seeing. Sinauer.
Kaiser, P. K. and R. M. Boynton (1996). Human Color Vision, Second Edition. Washington, DC, Optical Society of America.
Sharpe, L. T et al. (1999). Opsin genes, cone photopigments, color vision and colorblindness. In Color vision: From Genes to Perception. K. Gegenfurtner and L. T. Sharpe. Cambridge, Cambridge University Press: 3-51.
Hood, D. C. (1998). "Lower-level visual processing and models of light adaptation." Annual Review of Psychology 49: 503-535.
Any introductory texts on "Sensation and Perception" will cover topics D and E in some detail. For E, also look for books in the library on "Visual illusions", of which there are several.

Webvision at http://webvision.med.utah.edu/


Seminar 3. Visual cortex and pathways seminar (SS)

A. Does activity in the 'dorsal' visual pathway reach visual awareness? JB

References:

Milner  Vision without knowledge. Phil. Trans. R. Soc. Lond. B, 1997 352: 1249-1256.

Goodale & Milner  Separate visual pathways for perception and action Trends in Neuroscience 1992  15: 20-25

 

B. What is the difference between consciousness and attention? CG

References:

Crick and Koch   Consciousness and Neuroscience  Cerebral Cortex 1998 8:97-107.

Lamme  Why visual attention and awareness are different. Trends in Cognitive Sciences 2003 7:12-18.

 

C.  What is the 'unit' of attentional selection?

References:

Duncan J, Converging levels of analysis in the cognitive neuroscience of visual attention.  Phil Trans R Soc Lond B, 1998 353: 1307-1317.

O'Craven KM, Downing PE, & Kanwisher N, fMRI evidence for objects as

the units of attentional selection.  Nature, 1999 401: 584-587.

 

D. What is the 'biased competition' theory of attention?

References:

Desimone R, Visual attention mediated by biased competition in extrastriate visual cortex.  Phil Trans R Soc Lond B, 1998 353: 1245-1255.

Chelazzi L, Miller EK, Duncan J, & Desimone R, Responses of neurons in macaque area V4 during memory-guided visual search.  Cereb Cortex, 2001 11: 761-772.

 

E. What is the 'spotlight' of attention? TM

References:

Brefczynski JA & DeYoe EA, A physiological correlate of the 'spotlight' of visual attention.  Nature Neuroscience, 1999 2: 370-374.

Vidyasagar TR, A neuronal model of attentional spotlight: parietal guiding the temporal.  Brain Research  Reviews, 1999 30: 66-76.

 

F. What is the 'premotor' theory of attention?

References:

Corbetta, M., et al. A common network of functional areas for attention and eye movements. Neuron 21, 761-773 (1998).
Moore, T., Armstrong, K.M. & Fallah, M. Visuomotor origins of covert spatial attention. Neuron 40, 671-683. (2003).

 

G. What is "blindsight'? HS

References:

Stoerig, P. & Cowey, A. Blindsight in man and monkey. Brain 120, 535-559. (1997).
Weiskrantz, L. Roots of Blindsight. Progress in Brain Research 144, 229-241. (2004).

 

 

Additional attention references:

Kastner S. and Ungerleider L.G. (2001) The neural basis of biased competition in human visual cortex.  Neuropsychologia  39, 1263-76

Chun M.M. and Marois R. (2002) The dark side of visual attention.  Curr. Opin. Neurobiol.  12, 184-189.

Moore T.et al. (2003) Visuomotor origins of covert spatial attention.  Neuron  40, 671-683.

Reynolds J.H. and Chelazzi L. (2004) Attentional modulation of visual processing.  Annu. Rev. Neurosci.  27, 611-647
Shipp S. (2004) The brain circuitry of attention.  Trends Cogn. Sci.  8, 223-230.