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BIOL 415 Nerve cell mechanisms in behavior
Test 2 Tuesday March 29, 2016 ­p; Prof. Stark
All questions are short answer. 65 points total
For questions 1-4, go here
1. What kind of information is being carried by this tract?
2. State ONE of the functions of this nerve seen coming out of the cerebral
eye movements, eyelid movements (somatic motor), pupil constriction, accomodation
3. These fibers, hidden as they pass under the pons, form what tract?
4. Here it is called the pons. What do you call these fibers, on the "other
side," in the dissection of the 3 components of the cerebellar peduncle?
brachium pontis or middle cerebellar peduncle
For questions 5-8 go here
5. The brains provided for your dissection still had this white "membrane"
(called what?) that you were required to remove before proceeding.
6. You removed the gray matter of what major structure to reveal this tract?
7. Answer EITHER (1) What is the name of this structure? OR (2) If you removed
it, name ONE of the things you would see.
septum pellucidum, lateral ventricle or head of caudate
8. If you removed this structure, what major subdivision of the diencephalon
would you be looking at?
For 9-12, go here
9. What is this structure?
10. The postsynaptic cells in this area receive their input from cells that
are located where?
retina (ganglion cells)
11. 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
12. What is the name of the ventricle you see here?
For 13-16, go here
13. For this figure, ANSWER EITHER (1) What is it called when the entire
white matter under the cortical gray matter is exposed? OR (2) What is the
term used for these particular axons?
corona radiata, arcuate fibers
14. What is this structure?
superior colliculus (lamina quadrigemina)
15. What is this structure?
16. ANSWER EITHER (A) Using a tract name, what is the white matter that
is being ripped? OR (B) Using a tract name, why is the outside of this structure
internal capsule, the fimbria covers the hippocampus
17. In the corticospinal tract, motor cells in the precentral gyrus make
their first synapse (where?).
to the spinal motor neuron in the ventral horn
18. You have a rat brain atlas and your anesthetized rat (in an approved
protocol) is mounted in a stereotactic device with the skull exposed. Say
something about what you need to do to get the tip of an electrode into
the ventromedial nucleus of the hypothalamus.
measure from the bone sutures*, drill a hole, lower the electrode to the
correct depth*, *=requires consulting the atlas
19. How did Pruisinger propose that a protein (without DNA or RNA) can be
infectious and alter the proteins in the victim, making those proteins infectious.
protein in scrapie configuration converts protein in control configuration
into the scrapie form
20. Using the terminology (5 compartments from Telencephalon to Myelencephalon),
say where you find the third ventricle
21. Which one of the three cranial nerves that control eye movements via
extraocular muscles also has other motor controls relevant to the eye?
22. With your "orange stick," you scrape all the gray matter out
of one sulcus. Answer either (1) How can you tell what direction the myelinated
axons run? or (2) Where do the first axons you find come from and go to?
stick glides in axon direction and scrapes across the grain, from and to
the adjacent gyri
23. What is missing from this list of gray matter components of the telencephalon:
Cerebral cortex, Basal ganglia, Olfactory bulb, Basal forebrain?
24. For (1) striatum OR (2) lenticular nucleus, explain how the body got
striated because of branches of internal capsule, shaped like a convex lens
in horizontal section
25. 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.
26. Group IA sensory afferent neurons ANSWER EITHER (1) come in from what
receptors? OR (2) have their cell bodies where?
muscle spindles, dorsal root ganglion
27. Capsaicin stimulates the VR-1 receptor. ANSWER EITHER (1) What would
be the "normal" (biologically relevant) stimulus? (2) What related
Drosophila mutant was discovered much earlier? OR (3) Say something about
the molecular structure of this receptor.
heat, transient receptor potential, channel
28. The gracile nucleus is ANSWER EITHER (1) located where? OR (2) is in
a branch of the somatosensory system called what?
caudal medulla, lemniscal system
29. "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
30. Your text has a picture of dermatomes. Why was the face not included
in that picture?
face input is via trigeminal, not spinal segments
31. The anterolateral system is for pain. There is a notable exception (in
terms of spinal tract location). ANSWER EITHER (1) What type of pain is
carried in this exceptional tract? OR (2) Where in the spinal cord is it
viceral, dorsal columns at midline
32. In contrast with the input via the dorsal root of the spinal cord, where
does somatosensory information from the face come in?
33. Tell me a place where the 2-point discrimination threshold for fine
touch is less than 5 mm.
fingertips, lips, tongue
34. A human rod is very sensitive. Why is it theoretically impossible for
it to be more sensitive?
it is stimulated by a single photon, the smallest quantum of light
35. Say something about why vision, as we know it, would not work for wavelengths
far below or above "visible wavelengths."
too short is ionizing (also cut off by ozone layer), just right excites
electrons, too long vibrates molecules (heat is waste)
36. 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
37. "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
38. The ciliary muscle is contracted. ANSWER EITHER (1) What nerve innervates
this muscle? OR (2) What type of vision is this good for?
3-oculomotor, near vision
39. What disorder leads to tunnel vision and why?
retinitis pigmentosa b/c of mid periphery rod loss
40. 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
41. 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)
42. "You can walk through the forest with nothing but star light, but
you cannot run." Why not?
phototransduction is slow
43. In terms of cGMP levels, explain why the rod hyperpolarizes in response
with the cation channel continuously gated by cGMP in the dark, the cell
is depolarized, and when PDE is activated in phototransduction, the channel
closes because cGMP has been turned into 5' GMP
44. 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
45. 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
46. 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
47. On the way to the thalamus, what is different about axons from the nasal
vs the temporal retina at the optic chiasm?
temporal stays ipsilateral, nasal crosses to contralateral
48. Regarding feature detection, what and where is a "bug detector?"
in the frog retina, ganglion cells respond to small dark moving dots
49. Simple cells respond to a line at an angle. These cells presumably receive
inputs from an organized subset of lateral geniculate neurons whose receptive
field organization is (what?).
50. What aspect of visual development prompted me to draw a parallel to
imprinting of mother's image in precocial geese?
the 2 & 1/2 month sensitive (critical) period after birth required for
binocular vision in the development of normal binocular cortical connectivity
51. As an electrode is advanced obliquely, the ocular dominance changes.
What else changes?
the orientation preference
52. Injection into one eye followed by a specialized histological technique
demonstrated a zebra-stripe pattern of ocular dominance columns in the visual
cortex. ANSWER EITHER (1) What was injected in the eye? OR (2) What technique
was used for the visualization in the cortex?
a radioactive amino acid, audioradiography
53. 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 logarithmically, abscissa
is frequency in Hz where log plotting is for convenience
54. 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
55. Tip links assist channels (ANSWER EITHER) (1) for what ion? Or (2) located
on what specific subcellular component?
56. Where is the first place in the auditory projection that receives bilateral
superior olive (mid-pons)
57. How do insectivorous bats use sound to catch their prey?
58. Name (OR give the number for) an efferent cranial nerve that would mediate
eye movements controlled through the vestibular system.
occulomotor III, abducens VI (also trochlear IV)
59. In addition to the semicircular canals, what are the two organs that
detect head movement?
60. How many alleles of the PTC taster gene are there in most of the human
just taster and non-taster
61. T1R3 is a G protein-linked receptor used to mediate sweet and umami
tastes. What is unique about its interactions with other membrane proteins
relative to any other G protein-coupled receptor we have covered in this
dimerizes with T1R2 (sweet) and T1R1 (amino acids)
62. 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
63. A male moth is excited by a female's sex attractant pheromone at a concentration
of one molecule per cubic foot. How does he know which way to fly?
64. For cAMP in olfactory receptor cells, answer either (1) What enzyme
makes it? Or (2) What does it do?
adenylate cyclase, gates a sodium-calcium channel
65. For mammalian olfaction, say something about EITHER (1) the domain structure
of each protein molecule OR (2) the intron-exon structure of each gene.
seven trans-membrane domains, no introns
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