Vision Exam Questions PDF

+-----------------------------------+-----------------------------------+ | **[QUESTION]** | **[ANSWER]** | +===================================+===================================+ | What is the visual light spectrum | 380 -- 740 nm | | wavelength range?...

+-----------------------------------+-----------------------------------+ | **[QUESTION]** | **[ANSWER]** | +===================================+===================================+ | What is the visual light spectrum | 380 -- 740 nm | | wavelength range? | | +-----------------------------------+-----------------------------------+ | Images in the eye are formed by | Refraction | | **\_\_\_\_\_**, which is the | | | bending of light rays | | +-----------------------------------+-----------------------------------+ | What is the cornea? | The transparent external surface | | | of the eye that bends incoming | | | light | +-----------------------------------+-----------------------------------+ | What is the pupil? | The opening through which light | | | enters the eye | +-----------------------------------+-----------------------------------+ | What is the iris? What does it | The colored portion of the eye; | | do? | it can vary the size of the pupil | +-----------------------------------+-----------------------------------+ | What does the lens do? | Helps focus light on the retina | +-----------------------------------+-----------------------------------+ | What is the retina? | Layer of neurons at the back of | | | the eye; has photoreceptors (rods | | | and cones) | +-----------------------------------+-----------------------------------+ | What is the fovea? | The part of the retina with the | | | most cones (highest visual | | | acuity) | +-----------------------------------+-----------------------------------+ | What carries visual information | Optic nerve | | from the eye to the brain? | | +-----------------------------------+-----------------------------------+ | What do the ciliary muscles do? | Accommodation -- causing nearer | | | or farther images to come into | | | focus by adjusting the shape of | | | the lens | +-----------------------------------+-----------------------------------+ | What is the difference between | **HYPEROPIA** is farsightedness | | hyperopia and myopia? | when your eyeball is short (use a | | | convex lens to correct). | | | **MYOPIA** is nearsightedness | | | when your eyeball is long (use a | | | concave lens to correct) | +-----------------------------------+-----------------------------------+ | 1. In the retina, what is the | 1. **GANGLION CELL LAYER, | | order of cell layers in which | BIPOLAR CELL LAYER, | | light hits first | PHOTORECEPTOR LAYER,** | +-----------------------------------+-----------------------------------+ | 2. In the retina, what is the | 2. **PHOTORECEPTORS, (HORIZONTAL | | order of cells in which the | CELLS), BIPOLAR CELLS, | | light is processed? | (AMACRINE CELLS), GANGLION | | | CELLS** | +-----------------------------------+-----------------------------------+ | Which cells generate action | Ganglion cells (all other cell | | potentials? | types in the eye generate graded | | | potentials) | +-----------------------------------+-----------------------------------+ | What do Horizontal cells do? | Modify responses of bipolar cells | +-----------------------------------+-----------------------------------+ | What do Amacrine cells do? | Modify responses of ganglion | | | cells | +-----------------------------------+-----------------------------------+ | 3. What pigment, what receptive | 3. Rods v. Cones | | field size, and what is the | | | best setting for each of the | a. **RODS**- contain | | photoreceptors? | **RHODOPSIN**, have | | | **LARGE RECEPTIVE | | | FIELDS**, and work best | | | in **DIM LIGHT**. They | | | are in the **PERIPHERY** | | | of the retina and do not | | | distinguish color. | | | | | | b. **CONES**- contain | | | **IODOPSIN**, have | | | **SMALL RECEPTIVE | | | FIELDS**, and work best | | | in **BRIGHT LIGHT**. They | | | are in the central retina | | | (**FOVEA**) and | | | distinguish color. | +-----------------------------------+-----------------------------------+ | 4. Explain how transduction | 4. **LIGHT CLOSES NA+ CHANNELS, | | happens in the rods. | HYPERPOLARIZES**, and **TURNS | | | RODS OFF** (Rods are | | | generally firing in the | | | dark!!). When rods | | | (photoreceptors) are turned | | | off, **BIPOLAR CELLS** can | | | turn on and send a signal to | | | the **GANGLION CELLS** to | | | depolarize and conduct an | | | action potential. | | | | | | c. At high illumination in | | | sunlight, all sodium | | | channels are closed, | | | because the rods are | | | saturated. This shows | | | just how sensitive rods | | | are to light! | +-----------------------------------+-----------------------------------+ | 5. When light strikes rhodopsin, | 5. **RETINAL**, a vitamin on the | | what is activated? | protein Opsin. There is a | | | **RPE65** conformation change | | | from bent to straight. This | | | is TRANSDUCTION from light to | | | chemical energy. | +-----------------------------------+-----------------------------------+ | 6. If the RPE65 is defective, | 6. You have **LEBER'S CONGENITAL | | what disorder do you have? | OPTIC DEGENERATION**, in | | How can this be cured? | which photoreceptors | | | degenerate and the patient | | | goes blind. STEM CELLS have | | | cured this disease. | +-----------------------------------+-----------------------------------+ | What is the Visual Pathway? | Retina Optic Chiasm Lateral | | | Geniculate Nucleus (thalamus) | | | Visual Cortex (occipital lobe) | +-----------------------------------+-----------------------------------+ | 7. GY has an injury to the | 7. In **BLINDSIGHT, V1 IS | | occipital cortex. He can't | BYPASSED**, but other | | see light, but he accurately | information can still reach | | points to it 99% of the time. | V2 and V5 because of the many | | Why? | minor pathways into | | | extrastriate cortex. GY | | | cannot make mental images, | | | but he has some kind of | | | unconscious vision that helps | | | him "see" his surroundings. | +-----------------------------------+-----------------------------------+ | What are the Magnocellular | d. Magnocellular cells detect | | "M-cells" cells in the LGN? What | **MOTION, LOCATION**, and | | do they detect? (M channel) | brightness contrast. This is | | | the **WHERE PATHWAY**. They | | | can easily tell if something | | | is moving toward or away from | | | us. Again, these cells are | | | big and you don't need a lot | | | of them! | | | | | | e. Thus, this channel and | | | pathway is important for | | | **ANALYSIS OF OBJECT | | | MOTION**. This channel is | | | orientation selective, | | | directional sensitive for | | | movement, and there is no | | | color sensitivity, as | | | expected!\ | | | M cells Magnocellular Layers | | | **DORSOLATERAL | | | PARIETOTEMPORAL CORTEX** | +-----------------------------------+-----------------------------------+ | What are the Parvocellular | a. Parvocellular cells are | | "P-Cells" cells in the LGN? What | important for distinguishing | | do they detect? | **SMALL FINE DETAIL**. The | | (Parvocellular-Interblob Channel) | small receptive field acts | | | similarly to a pixel. The | | | smaller, the more detail. | | | This is the **WHAT PATHWAY**. | | | You need a lot of pixels. | | | | | | b. Thus, this channel and | | | pathway is important for | | | **ANALYSIS OF OBJECT SHAPE**. | | | This channel has high | | | orientation sensitivity, no | | | color sensitivity, and small | | | receptive fields, as | | | expected.\ | | | P cells Parvocellular Layers | | | **INFERIOR OCCIPTOTEMPORAL | | | CORTEX (V4)** | +-----------------------------------+-----------------------------------+ | 8. Explain Koniocellular | a. Koniocellular cells are | | "K-cells" cells. (Blob | important for **COLOR | | Channel) | ANALYSIS** | | | | | | b. Thus, this channel and | | | pathway is important for | | | **ANALYSIS OF OBJECT COLOR** | +-----------------------------------+-----------------------------------+ | 9. Neurons in the retina and LGN | 8. Receptive Fields are what | | have two types of receptive | make the cell fire. The | | fields. What are the | bipolar cell responds with | | differences between them? | changes in polarization. The | | | ganglion cell responds with | | | frequency of action | | | potentials. | | | | | | f. **ON-SURROUND/OFF-CENTER* | | | *: | | | If you stimulate a little | | | in the surround, you are | | | a little excited. If you | | | stimulate a lot in the | | | surround, you are | | | maximally excited. If you | | | stimulate a little in the | | | center, you are a little | | | inhibited. If you | | | stimulate a lot in the | | | center, you are maximally | | | inhibited. If you | | | stimulate both in its | | | entirety, the signals | | | cancel out. Excitation | | | sends signals to the | | | brain. | | | | | | g. **ON-CENTER/OFF-SURROUND* | | | *: | | | If you stimulate a little | | | in the center, you are a | | | little excited. If you | | | stimulate a lot in the | | | center, you are maximally | | | excited. If you stimulate | | | a little in the surround, | | | you are a little | | | inhibited. If you | | | stimulate a lot in the | | | surround, you are | | | maximally inhibited. If | | | you stimulate both in its | | | entirety, the signals | | | cancel out. Excitation | | | sends signals to the | | | brain. | +-----------------------------------+-----------------------------------+ | 10. What is the function of V1? | 9. **V1 breaks down the visual | | | image into components** | +-----------------------------------+-----------------------------------+ | 11. What is the function of V2? | 10. **V2** is the second visual | | | cortex. This perceives | | | complex form and is important | | | for **"FILLING IN THE | | | GAPS".** Much of vision is | | | extrapolating (predicting) | | | from what is actually "seen". | +-----------------------------------+-----------------------------------+ | What is the function of V4? | **V4** also perceives complex | | | form. It responds to **CONCENTRIC | | | AND RADIAL STIMULI**, **ANYTHING | | | ROUND**. It is also involved in | | | **COLOR** perception along with | | | the koniocellular cells, which | | | are spread throughout the | | | thalamus | +-----------------------------------+-----------------------------------+ | 12. What is the importance of V5? | 11. Motion detection; rods are | | | most sensitive to motion. If | | | you have akinetopsia, you | | | have motion blindness | +-----------------------------------+-----------------------------------+ | What is the difference in Simple | h. Simple cortical cells are | | Cortical Cells and Complex | line detectors. They are part | | Cortical Cells? | of the recognition/location | | | system. They are more | | | responsible to **NEW FLASHES | | | OF LIGHT**, than to static, | | | steady illumination or | | | diffuse illumination. One | | | orientation and location | | | specific. If it is not that | | | orientation, it will not fire | | | | | | i. Cortical cells act just like | | | simple cells except they | | | don't care about **WHERE** in | | | the visual field something is | | | coming from. They are more | | | concerned with recognizing | | | external objects. They take | | | input from all. Anytime | | | simple cells fire, complex | | | cells automatically fire. | +-----------------------------------+-----------------------------------+ | 13. The process that acts to | 12. Lateral inhibition | | enhance the boundaries of | | | visual objects in order to | | | produce contrast is called... | | +-----------------------------------+-----------------------------------+ | 14. What is the Trichromatic | j. The **TRICHROMATIC | | hypothesis? | HYPOTHESIS** says there are | | | three types of cones (small, | | | medium, and large), each | | | responding to a part of the | | | spectrum and its own separate | | | pathway to the brain. | | | Afterimages are NOT | | | supported/explained by this | | | theory. | +-----------------------------------+-----------------------------------+ | 15. What is the Opponent-Process | 1. The **OPPONENT-PROCESS | | hypothesis? | HYPOTHESIS**- three color | | | axes have opposed pairs of | | | colors. Cells in the retinal | | | ganglion and thalamic | | | parvocellular layers fire to | | | some wavelengths, and are | | | inhibited by others. | | | | | | a. When one member of the | | | color pair is "fatigued", | | | inhibition of its | | | corresponding pair member | | | is reduced. This | | | increases the relative | | | activity level of the | | | unfatigued pair member, | | | and so its color is | | | perceived. | | | | | | b. Two color opponents fight | | | each other. Cells that | | | respond to, say, red, | | | inhibit responses to | | | cells that respond to | | | green. You can only look | | | at red for so long before | | | it gets weaker and | | | weaker. Once you take | | | your eyes away, green | | | cells are able to easily | | | inhibit red cells\ | | | Afterimages ARE supported | | | by this theory. | +-----------------------------------+-----------------------------------+ | 16. What do you call it when you | 13. **SYNESTHESIA** -- everyone | | experience one sensory | has it, but 4% of the | | modality as another? | population has strong cases | | | of it. The visual and frontal | | | cortex may be activated by | | | spoken words, for example, | | | seeing the number 5 as blue. | +-----------------------------------+-----------------------------------+ | 17. What is Alice in Wonderland | 14. When **MICROPSIA** (small | | Syndrome? | vision) and **MACROPSIA** | | | (big vision) alternates. | | | Occurs in migraine, **EBV** | | | ("mono") infection, and | | | commonly in children. There | | | is a problem with **V5**!!!! | +-----------------------------------+-----------------------------------+ | 18. If you cannot perceive a | 15. **SIMULTAGNOSIA**- an | | visual scene as a whole, like | inability to attend to more | | a dollar, dinner table, or | than a very limited area of | | "forest for the trees", what | the visual field despite | | do you have? | normal vision. There is a | | | problem with the | | | **INFEROTEMPORAL CORTEX**, | | | and this is the end of visual | | | analysis. | +-----------------------------------+-----------------------------------+ | 19. When patients see | 16. **PALINOPSIA**- objects in | | AFTERIMAGES, what do they | motion have a continual | | have? Why? | tracer normally, but in this | | | case, **V5** is slow. It is | | | failing to tag multiple | | | images correctly. They may be | | | out of order, even! There is | | | bilateral occipital cortex | | | and middle cortex damage. | +-----------------------------------+-----------------------------------+ | 20. If you have normal sensation | 17. **VISUAL AGNOSIA/OPTIC | | and speech, but cannot name | ATAXIA**- you can't name the | | objects, what do you have? | object based on seeing it. | | | You can't use visual cues to | | | guide movement to it, either. | | | However, if the object was in | | | your hands, you could tell | | | what it is. In this case, | | | **V5** and the angular and | | | inferotemporal cortex are not | | | functioning properly. | +-----------------------------------+-----------------------------------+