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BIOL 415 Nerve cell mechanisms in behavior
BIOL 615 Neural bases of behavior
Test 2 Thursday March 27, 2014 – Prof. Stark
All questions are short answer. 65 points total
1. Why doesn't the alpha subunit of the heterotrimeric G protein activate the effector
protein forever?
there is GTPase activity, and when it is bound to GDP, alpha reassociares with betagamma and is no longer activated
2. In the Gq pathway, state ONE of the products of phospholipase C (PLC).
diacylglycerol and IP3
3. How does caffeine produce its stimulation?
potentiating NE by inhibiting cAMP breakdown
4. 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
5. At first, Pruisinger's Nobel Prize winning proposition that a protein, (not a virus or
bacterium, no DNA or RNA) was preposterous. How can a protein be contagious?
an altered conformation (PrP-Sc) can turn your normal protein (PrP-C) into the altered
form
6. Using the terminology (5 compartments from Telencephalon to Myelencephalon), say
where you find the third ventricle
diencephalon
7. In the midbrain, you see the lamina quadrigemina. Give the name of the visual portion
of this structure for EITHER (1) the frog OR (2) the sheep.
optic tectum superior colliculi
8. In that area called the pons, there are fibers that your text calls the "middle cerebellar
peduncle." When you looked at the floor of the fourth ventricle and teased apart the three
cerebellar peduncles, give a different name for what it was called. (Hint, not restiform
body or brachium conjunctivum)
brachium pontis
(For figures 9-12, refer to)
9. You ran your "orange stick" to note the rostral-caudal direction of these fibers. Answer
EITHER (1) the name of ONE of these structures, (2) the function of these fibers, OR (3)
the name of this tract.
cerebral peduncle, trapezoid body, motor system, cortico-spinal tract (pyramidal tract)
10. You removed the gray matter of what major structure to reveal this tract?
cerebellum
11. 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
12. If you removed this structure, what major subdivision of the diencephalon would you
be looking at?
hypothalamus
(for questions 13-17, refer to)
13. Using a tract name, what is the white matter that is being ripped?
internal capsule
14. Using a tract name, why is the outside of this structure white?
the fimbria covers the hippocampus
15. What would this structure be called if this were a frog?
optic tectum
16. Name ONE of these cranial nerves (A or B).
trigeminal or abducens
17. What is the function of the white matter you can see through the brain’s surface here?
olfaction
(for questions 18-20, refer to )
18. If you pulled the two cerebral hemispheres apart here at the medial longitudinal
fissure, what white matter would you see?
corpus callosum
19. With respect to its speckled appearance, how do neuroanatomists refer to this view of
the basal ganglia?
striatum
20. The postsynaptic cells in this area receive their input from cells that are located
where?
retina (ganglion cells)
21. What tract was found just caudal to (and parallel to) the fornix by removing gray
matter from the massa intermedia?
mammilo-thalamic tract
22. Occulomotor nucleus, trochlear nucleus, and (what?) innervate the extraocular
muscles of the eye.
abducens
23. “Archipallium” is a term for what structure?
hippocampus
24. Between sacral and lumbar areas of the spinal cord the typical structure often
depicted in cross sections ends. What is the name given to the structure caudal to that
location?
cauda equina
25. There are several enlargements in the spinal cord. ANSWER EITHER (1) Give the
name of one. OR (2) What cells are more numerous in these areas? OR (3) Why is the
spinal cord larger in these two places?
cervical and lumbar enlargements, motor neurons, to supply forelimbs and hindlimbs
26. For the pyramidal tract, ANSWER EITHER (1) Where is the cell body where this
tract originates? OR (2) Where is the synapse?
precentral gyrus, spinal motor neuron
27. Some of the somatosensory system’s afferents are unmyelinated. What submodality
(quality) is coming up these C fibers?
pain
28. Say something about the receptive field of the Pacinian corpuscle
it is large
29. 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
30. VR-1 receptors ANSWER EITHER (1) can be stimulated intracellularly by what
chemical? OR (2) are stimulated extracellularly by what natural stimulus?
capsaicin, heat
31. 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
32. 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
33. Why is there a contralateral loss of sensation of temperature and pain below a half
spinal cord injury?
because the decussation is at the point of entry
34. Referred pain from the ureter to the lower back is most commonly expressed in what
situation in people?
kidney stone
35. 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
36. ANSWER EITHER (1) How would a vision researcher attenuate (decrease) the
intensity of his or her light beam by 1/16? OR (2) How was I able to convince you that
ultraviolet (UV) light was coming out of the monochromator when you could not see it?
use a 1.2 log unit neutral density filter, show the UV-induced blue fluorescence of paper
37. ANSWER EITHER (1) Even if an animal did have visual sensitivity to UV-B light
(below 300 nm), why would this not be useful? OR (2) Even though infrared light does
not interact with matter the same way that “visible” light does, some animals have
something approximating vision for infrared light; say something about this.
there is no light in that range passing the ozone layer, snakes like pit vipers can image the
heat of their prey with pit organs
38. Humans have rod rhodopsin and 3 types of cone rhodopsins. In a pair-wise
comparison, which two have the minimum difference in amino acids?
long (yellow) vs middle (green)
39. “The cornea is actually the strongest lens in the eye.” Say something about this.
everything is blurred under water without goggles, the power is 42 diopters, the
difference in index of refraction between air and ocular media is huge
40. “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
41. Why does the eye care professional (ophthalmologist or optometrist) take your eye
pressure when you come in?
high pressure from obstructed drainage of the aqueous humor through the canal of
Schlemm leads to glaucoma in which the ganglion cells die
42. “Ring scotoma tunnel vision” Say something about this disorder or why it is so tragic.
retinitis pigmentosa, young people go blind, rods degenerate, mutations of molecules of
the visual transduction cascade
43. 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
44. Why might erectile dysfunction medications such as Viagra affect visual receptor
function?
a cGMP PDE is inhibited
45. Why do visual receptors hyperpolarize in response to light?
a sodium – calcium channel closes
46. Say something about contrast detection in the Limulus eye.
lateral inhibition, Mach bands, neural response as a function of space is accentuated
relative to light gradient
47. A light is shown into the left eye and neither pupil constricts, but if it is shown into
the right eye, both pupils constrict. Which cranial nerve is at fault?
left optic
48. Layers 1, 4 and 6 receive contralateral input while layers 2, 3 and 5 receive ipsilateral
input. These layers are in what structure?
lateral geniculate nucleus
49. As an electrode is advanced obliquely, the ocular dominance changes. What else
changes?
the orientation preference
50. The ocular dominance columns in the cortex show up on an autoradiogram. Say
something about how the radioactivity arrived there.
inject radioactive amino acid into one eye, axon transport to LGN, crosses synapse
(amazingly) then axon transport to cortex
51. 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
52. In the frequency discrimination demonstration, how did you know that the two tuning
forks differed by only a few Hz?
there were only a few beats per second
53. What is the significance of 0.0002 dynes per square cm?
it is the denominator of the pressure ratio in the definition of dB=20 log ratio
54. ANSWER EITHER (1) What is it called when the frequency is over 20,000 Hz?
OR (2) Say something about hearing in that range.
ultrasound, bats use it for echolocation and dogs can hear it
55. 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
56. 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
57. Where is the first place in the auditory projection that receives bilateral input?
superior olive (mid-pons)
58. 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
59. The vestibular nucleus feeds to the abducens nucleus which, in turn, feeds to the
lateral rectus plus (what nucleus?).
oculomotor nucleus
60. In addition to input from vestibular apparatus, the vestibular nuclei that form the
vestibulo-spinal tracts receive input from what major brain location?
cerebellum
61. Bitter taste receptors are what kind of molecule?
g protein coupled receptor, T2R, TRA2R would be acceptable
62. In what way are the receptors unusual and unique for sweet and umami tastes?
this is the only time the G protein coupled receptors have been mentioned as being
dimers
63. Say something about the genetics of PTC taste sensitivity.
the T allele is dominant, so only tt is non-taster
64. The solitary nucleus gets input from nerves VII, IX and X, and it feeds to the
thalamus and (say another place).
amygdala, hypothalamus
65. In addition to the 5 primary taste receptors that input via nerves VII, IX and X, say
something about either the chemical ("tastant") or the receptor type, or the nerve input
mediating appreciation of food at the level of watery stimulation in the mouth.
capsacin, polymodal niciceptive fibers, V = trigeminal