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BIOL 415 Nerve cell mechanisms in behavior
Test 2 Thursday March 30, 2017 ­p; Prof. Stark
All questions are short answer. 65 points total

For questions 1-5 go here

1. Give a name, number or function of the cranial nerve indicated.

occulomotor, 3, eye movement, pupil, accomodation

2. Give the function (for both) or a name (for either) area of white matter indicated .

outgoing voluntary motor tract, cerebral peduncle, trapezoid body

3. What is this white area called?


4. Answer either (1) What is this structure called? Or (2) Say one of the things you would see if you removed that structure.

septum pellucidum, head of the caudate and lateral ventricle

5. What is this area called?

hypothalamus, third ventricle

For questions 6-9 go here

6. If you saw these fibers on the ventral view of the brain, how would that area be labeled?


7. In between the two lines marked "7," what major subdivision of the diencephalon is located here?


8. If you pulled the two cerebral hemispheres apart here at the medial longitudinal fissure, what white matter would you see?

corpus callosum

9. Name this structure (or give it's cranial nerve number)

olfactory bulb, I

For questions 10-15, go here

10. What is the name associated with the gray matter you needed to scrape away (from the mid-sagittal plane) to reveal this tract?

massa intermedia, thalamus

11. What is this white matter called?

corpus callosum

12. What is the white matter on the outside of this structure called? (Alternatively, you could say one of the tracts on the midsagittal slice you see that are formed from these axons.)

fimbria, fornix, hippocampal commissure

13. What is this white matter called?

internal capsule

14. What is this large structure in the middle of the brain called?


15. Caffeine inhibits what enzyme?


16. Before Pruissinger's prion hypothesis... answer either (1) What kind of disease? was explained by Nobelist Gadjusec by a virus? (2) A virus with what special kind of properties?

spongiform encephalitis, CJD, kuru, etc.; slow

17. One product of phospholipase C (PLC) is inositol tris-phosphate. What is IP3's downstream action?

ligand to channel to release calcium from cistern

18. Your research mentor assigns you to lesion the rat's FPVH, a nucleus in the hypothalamus. You find it in the stereotactic atlas on one coronal section called "-1.5" at a depth of -2 at 0.75 lateral to midsagittal. Say something about how you aim the electrode tip to that location.

mounting the head in a stereotactic apparatus will allow you rostral-caudal measurements if you know bregma and lamda and the rest is under micrometer control

19. What two portions of the brain (one in the metencephalon, the other in the myelencephalon) house the nuclei of cranial nerves # 5 (trigeminal) to # 12 (hypoglossal)?

pons and medulla

20. Using the terminology (5 compartments from Telencephalon to Myelencephalon), say where you find the third ventricle


21. Protein kinase A (PKA): ANSWER EITHER (1) In the pathway that uses Gq instead of Gs, what is in the cascade in place of PKA? OR (2) In the pathway that uses Gi instead of Gs, what happens to cAMP levels when the pathway is activated?

PKC or calcium release, decrease

22. Stimulation of 9 square mm of skin affects one Merkl disk; by contrast, stimulation of 60 square mm of skin affects one Ruffini end organ. Thus the Ruffini has a larger (what is the expression?) than the Merkl.

receptive field

23. What is the difference between the gracile and cuneate tracts?

gracile is information from lower limbs, cuneate from upper

24. Capsaicin gates the VR-1 receptor. ANSWER EITHER (1) What Drosophila visual mutation led to the founding of this family of channels? OR (2) Under normal physiological conditions, how is this receptor stimulated?

transient receptor potential, heat

25. In the human diving reflex, there is a seemingly contradictory decrease in pulse and increase in blood pressure mediated by sensory input from what cranial nerve?

5, trigeminal

26. Where do neospinothalamic and paleospinothalamic systems decussate?

at the point of entry

27. "In the Brown-Sequard syndrome, you have an ipsilateral loss of touch as mediated by the lemniscal system." ANSWER EITHER (1) What is the nature of the lesion? OR (2) What and where is the alternative sensory loss?

lesion halfway across the spinal cord, contralateral loss of anterolateral system

28. Why isn't the face included in the diagram of dermatomes?

trigeminal cranial nerve input is separate from segmented spinal cord input

29. Tell me a place where the 2-point discrimination threshold for fine touch is less than 5 mm.

fingertips, lips, tongue

30. For the nociceptor, ANSWER EITHER (1) Where is its first synapse? (2) What is the presynaptic transmitter at the pain cell's terminal OR (3) Where does the postsynaptic neuron project?

in the dorsal gray matter of the spinal cord, enkephalin, thalamus

31. A person who had had emmetropia (normal vision) developed hyperopia. Another person who had had emmetropia developed presbyopia. Answer either (1) What kind of corrective lens would help in both situations? Or (2) What is the difference in these two disorders?

convex lens, hyperopia is far sightedness person would always wear glasses, presbyopia is loss of accomodation, person would need reading glasses

32. "The cornea is the strongest lens in the eye." Explain this in terms of relative indices of refraction.

the air to cornea interface is the only large difference in index of refraction, so the corneal curve has a profound effect

33. Why would the ophthalmologist blast holes in the retina with a laser?

prevent further angiogenesis in diabetic retinopathy

34. One published article in vision gives the intensity of the stimulus in units of energy. Another visual scientist wants to know the intensity in quanta per square centimeter per second. What equation would (s)he use to figure that out?

the energy of a quantum of light, energy equals Planck's constant times the frequency of light

35. ROYGBIV. This is a series. If that series continued, what wavelength is next?

ultraviolet (UV)

36. "You would be able to see a letter that is 5 minutes." What is the more conventional way of saying that?

you have 20:20 vision

37. It might be better to say that "Light stops photoreceptor depolarization" than to say "Light causes photoreceptors to hyperpolarize." Justify.

in the dark, cGMP keeps sodium-calcium channels open

38. A radioactive amino acid allowed the rod outer segment disks closest to the inner segment to be labeled. On the basis of this methodology, what fundamental finding ensued?

that new outer segment is continuously made, the outer segment turns over, old outer segment is phagocytosed by the retinal pigment epithelium

39. What disorder leads to tunnel vision and why?

retinitis pigmentosa b/c of mid periphery rod loss

40. Unequal crossing over leading to gene duplication explains what phenomenon in the visual system?

evolution of two long wavelength cone opsins such as old world monkeys, apes and humans have from one such as new world monkeys have

41. There is a yellow pigment in front of the fovea. Answer either (1) What are the chemicals? (2) What are these pigments called? (3) What is the function of these pigments?

carotenoids lutein and zeaxanthin, macular pigments, protect photoreceptors from blue light

42. "You can walk through the forest with nothing but star light, but you cannot run." Why not?

phototransduction is slow

43. A paper published in 1942 demonstrated that a rod can respond to a single photon of light. Say something about the methodology in this study.

human subject answered if he could see carefully calibrated 500 nm light; 6-14 quanta were absorbed by a 500 rod area (psychophysics)

44. How was the horseshoe crab Limulus used to show how contrast detection was enhanced by feature detection?

neural input from ommatidia at a light-dark boundry show a more accentuated gradient of activity

45. What is different about layers 1,4 & 6 vs 2, 3, & 5 of the lateral geniculate nucleus?

connected from contralateral vs ipsilateral retinas

46. In Hubel and Wiesel's work, there is moderate firing when a thin line of light is turned on right on the excitatory receptive field. What happens if a wide line of white is turned on, centered in the same place but extending to either side of where the thin line of light had been shown?

no firing b/c excitatory line is inhibited by surround

47. You have a slice of visual cortex from a cat that had had a radioactive amino acid injected into one eye. Say something about the method that would allow you to visualize ocular dominance columns.

autoradiography of histological slices of cortex works b/c protein made crosses synapses at the LGN

48. Monocular deprivation of form vision ANSWER EITHER (1) has what profound effect on the cortex? OR (2) if it is applied (when?).

eliminates ocular dominance columns from that eye, in the first few months of life

49. The human eye connects to the superior colliculus, in addition to other places, and that area helps to integrate eye and head movements. In the frog, what is the equivalent part of the brain called?

optic tectum

50. A stroke wipes out the connection of the pretectum to the contralateral Edinger-Westphal nucleus but not to the ipsilateral one. How could you infer this with a very simple non-invasive vision test on a cooperative subject?

there would still be a pupillary reflex but not in the contralateral eye

51. As an electrode is advanced obliquely, the ocular dominance changes. What else changes?

the orientation preference

52. The human audibility curve plots Y as a function of X. Answer either what is on the Y OR X axes.

ordinate is threshold plotted in intensity, plotted logarythmically, abscissa is frequency in Hz where log plotting is for convenience

53. In the frequency discrimination demonstration, why was it important to hold both tuning forks to one ear simultaneously?

to show, using beats, that they differed by just a few Hz

54. Mechanoreceptive channels in auditory hair cells are assisted by what structural specialization?

tip links, extracellular protein from one stereocilium to its neighbor

55. Given the data on how stimulation by sound causes vibrations in the basilar membrane, why is it astounding that you can tell the difference of stimuli that differ by just a few Hz?

because localization is crude, there is tremendous overlap in part of basilar membrane stimulated

56. "An open potassium channel leads to depolarization of the cell." How can this be?

because of high extracellular potassium in the endolymph

57. Cells in the auditory cortex are responsive to a narrow range of frequencies. By contrast, the tuning curve for a cell in cranial nerve VIII is wider. Bekesy, the Nobel Prize winner, argued that this was because of what type of processing?

lateral inhibition

58. A shear force between the hair cells and what structure bends the stereocilia?

tectorial membrane

59. ANSWER EITHER: (1) what the tonotopic organization of the primary auditory cortex looks like; or (2) how would you demonstrate the tonotopic organization of the primary auditory cortex?

cells that respond to low frequency at one end, high at the other, record from places and run through a range of stimulus frequencies and see which frequency each place responds to best--

60. Where is the first place in the auditory projection that receives bilateral input?

superior olive (mid-pons)

61. How do insectivorous bats use sound to catch their prey?

echolocation (sonar)

62. The vestibular nucleus feeds to the abducens nucleus which, in turn, feeds to the lateral rectus plus (what nucleus?).

oculomotor nucleus

63. In addition to the semicircular canals, what are the two organs that detect head movement?

utricle, saccule

64. Concerning the channel in amino acid and bitter taste receptors, ANSWER EITHER (1) What kind of channel is used? OR (2) What gates the channel?

trp, IP3

65. In addition to the 5 primaries for taste stimulation, with input via cranial nerves VII, IX an X, it is argued that stimulants like capsaicin contribute to our overall appreciation of gustation. Answer either (1) Which cranial nerve is used? Or (2) What is the term for the receptor type?

5 trigeminal, polymodal nociceptive

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last updated 3/29/17