Study Guide for Chapter 4

1.         You should be able to trace the path of visual information from the optic nerve to optic chiasm to LGN & superior colliculi to visual cortex. You should also be able to indicate lesions sites and their resulting deficits using perimetry charts.

2.         What is the function (as far as is known) of the superior colliculus?  What is the preferred stimulus for cells in the superior colliculus?

3.         What are multisensory cells?

4.         What is the structural and functional architecture of the LGN? (In other words, how many layers are there and what is their input? What kinds of cells are found in the layers—e.g. parvocellular or magnocellular?)

5.         What is a retinotopic map?

6.         What do the different layers of the LGN contribute to perception in terms of the quality of information? (Not each specific layer, but different aspects of the visual scene, such as color, acuity, etc. with respect to magno-, parvo-, and inter layers)

7.            Overall, how would you describe the contributions the LGN makes to vision? What is the reticular activating system?

8.         What is cortical blindness? What is a scotoma? What is cortical magnification?

9.         How many layers are there to the visual cortex? Which layer is the most complex? How many sub-layers are in this layer?

10.       What does orientation selectivity mean? How is this determined?

11.       What  response properties define simple cells, complex cells, and hypercomplex cells? (In other words, what are the essential features of each of these types of cells?)

12.       What is direction selectivity? What about size selectivity?

13.       What are monocular and binocular segregation? What is ocular dominance? What does it mean when a cell is a binocular cell?

14.       To what do blobs respond?

15.       What is a column? A hypercolumn?

16.       What kind of visual processing is accomplished beyond the primary visual cortex? (For this one, try to keep in mind that not much is known—it is truly the “wild frontier”--thus your answer to this will necessarily be brief.)

17.       You  need to understand what it means to discuss the “duality” of vision. What is the parietal (dorsal) stream and what type of information does it deal with? What is the temporal (ventral) stream and what does it deal with? Also, be aware that this “dual stream model” is not the only acceptable explanation for the functioning of the visual system.

18.       You should be able to describe “blindsight” in a general way (as described in Box 4.2 in your text).

19.       What is achromotopsia? Prosopagnosia? Akinetopsia? What do these disabilities tell us about vision and the brain?

20.       What is a feature detector? What are some of the problems with the feature detector hypothesis?

21.       How do neurons overcome the ambiguity problem?

22.       What does it mean to say the vision is constructive?

23.       In what ways is vision context-dependent? How does this relate to learning?