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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
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?
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?
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?
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
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
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.
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
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
lesion halfway across the spinal cord, contralateral loss of anterolateral
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
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
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
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?
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
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
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
58. A shear force between the hair cells and what structure bends the stereocilia?
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
superior olive (mid-pons)
61. How do insectivorous bats use sound to catch their prey?
62. The vestibular nucleus feeds to the abducens nucleus which, in turn,
feeds to the lateral rectus plus (what nucleus?).
63. In addition to the semicircular canals, what are the two organs that
detect head movement?
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?
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