The Central Visual System

Please answer the following 20 multiple choice questions.

1) The majority of the refractive power of the eye lies at the level of the  
     A) Lens  
     B) Cornea  
     C) Retina  
     D) Fovea  
    
2) All of the following are specialisations of the fovea EXCEPT  
     A) Absence of blood vessels  
     B) Pushing aside of ganglion cells and bipolar cells  
     C) Higher density of rod photoreceptors  
     D) Higher ratio of ganglion cells to photoreceptors  

3) Layers 3, 4, 5, and 6 of your left lateral geniculate nucleus are destroyed. You would have problems seeing  
     A) Color in your left visual field  
     B) Fast-moving stimuli in your right visual field  
     C) Fine details of objects in your right visual field  
     D) Fast-moving stimuli in your left visual field  

4) "Ganglion cells that are neighbours in the retina have axon terminals that are neighbours in central visual structures." This organisation is an example of  
     A) Retinotopic mapping  
     B) Antagonistic receptive fields  
     C) Center-surround organisation  
     D) The mapping of colour  

5) Through which order of structures will visual information pass from the retina to cortex?  
     A) Optic nerve, optic chiasm, optic tract  
     B) optic tract, optic chiasm, optic nerve  
     C) optic chiasm, optic nerve, optic tract  
     D) optic tract, optic nerve, optic chiasm  

6) At the optic chhiasm, the fibers from the retina across from one side of the brain to the other, a process called  
     A) Crossover
     B) Hemisection  
     C) Decussation  
     D) Fasciculation  

7) What is the purpose of the decussation at the optic chiasm?  
     A) To give a representation of both left and right visual hemifields to each side   of the brain  
     B) To have each visual hemifield processed by the contralateral side of the brain  
     C) To analyze the monocular segments with both sidees of the brain  
     D) To analyze the binocular visual field with both sides of the brain  

8) The MAJOR target of the optic tract in the human is the  
     A) Superior colliculus  
     B) Suprachiasmatic nucleus of the hypothalamus  
     C) Lateral geniculate nucleus of the thalamus  
     D) Visual cortex  

9) Beyond the optic chiasm (i.e. after axonal decussation), a lesion in any tract (i.e., optic tract of optic radiation) will cause which of the following symptoms?  
     A) Complete blindness  
     B) Tunnel vision  
     C) Loss of vision in the contralateral eye  
     D) Loss of the contralateral visual hemifield  

10) What is the biggest clue that information from different retinal ganglion cell types are kept separate in the LGN?  
     A) The presence of an LGN on each side of the brain  
     B) The fact that M-cells project only to layers 1 and 2 of the LGN  
     C) The fact that the LGN laminae are not flat but are bent around the optic tract  
     D) The fact that the LGN receivesfeedback input from the cortex  

11) Which of the following is NOT another name for primary visual cortex?  
     A) MT  
     B) Area 17  
     C) V1  
     D) Striate cortex  

12) The projection from the LGN to cortex is called the  
     A) Optic tract  
     B) Optic chiasm  
     C) Optic nerve  
     D) Optic radiation  

13) Which of the following is NOT a target of the optic tract  
     A) Suprachiasmatic nucleus of the hypothalamus  
     B) Superior colliculus  
     C) Visual cortex  
     D) Pretectum  

14) The fact that opn spiny stellate cells are found in layer IVC suggests that layer IVC is involved in what type of projections?
      A) Projecting back to the LGN  
      B) Projecting to the superior colliculus
      C) Projecting to the hypothalamus  
      D) Projecting to neighbouring layers of the cortex

15) Layers V and VI are incolced in long-range projections from cortex. WHich type of neuron would most likely be involved in such connections?  
     A) Pyramidal cells  
     B) Siny stellate cells  
     C) Smooth stellate cells  
     D) Clial cells  

16) Which layer of cortex receives the majority of input from the LGN?  
     A) Layer III  
     B) Layer IVB  
     C) Layer IVC  
     D) Layer V  

17) The majority of ganglion cells are _______, which have _______ receptive fields  
     A) M cells, large  
     B) M cells, small  
     C) P cells, large  
     D) P cells, small  

18) One of the first symptoms of glaucoma is loss of peripheral vision. This symptom is most likely due to  destruction of the axons of ______ cells with _______ receptive fields.  
     A) Ganglion, smaller  
     B) Ganglion, larger  
     C) Photoreceptor, smaller
     D) Photoreceptor, larger  

19) After a large earthquake, 100 million people are trapper in a large cave full of man-eating creatures. The only available light source is extremely weak, coming from bioluminescent (glowing) bacteria on the rocks. After 10 million years of living under these conditions, you would expect the population of this lost people to contain a high percentage of ______ in their retinas, compared with people living on the surface of the earth.  
     A) Rod photoreceptors  
     B) Cone photoreceptors

20) Visual cortex is divided into ________ layers.  
     A) Two  
     B) Four  
     C) Five  
     D) Six