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BIOL-415 Nerve cell mechanisms in behavior
BIOL-615 Neural bases of behavior
Second test - Thursday, March 26, 2009 - Prof. Stark
All questions are short answer. 65 points total.

For Questions 1-8, refer to the pictures on this page

1. Although it is operationally named the "massa intermedia," it is actually (what specific part of the brain?).


2. What is this conspicuous white structure seen in mid-sagittal section?

optic chiasm

3. From a different perspective, you peeled off the hippocampus and saw this. Answer either (1) What is it called (specifically)? Or (2) What (functional) system is it part of?

lateral geniculate nucleus of the thalamus, visual

4. From a different perspective, you saw this structure hiding in the lateral ventricle behind the septum pellucidum. What is it?

head of the caudate nucleus

5. What is the name of this colossal body?

duh, corpus callosum

6. The hippocampus, shown here, is associated with white matter over its surface plus two tracts that can be seen in (or near) mid-sagittal section. One of those three would suffice for the answer.

fimbria, fornix, hippocampal commisure

7. A structure associated with the visual system is here. Answer either (1) What is it called in the sheep? (2) What is it called in the frog? Or (3) In combination with a nearby auditory structure, both bilateral, what name indicates this foursome?

superior colliculus, optic tectum, corpora (lamina) quadrigemina

8. When you cut off the cerebellum and looked at the floor of the fourth ventricle, what was this structure called (viewed from that perspective)?

brachium pontis of the cerebellar peduncle

For questions 9-12, see these figures

9. You can see this tract of white matter on the ventral surface of the brain. What system is it part of?

10. Suppose I'm pointing to the diencephalons, not the ventricle. What part of the diencephalons is this?


11. This and the nearby tracts and the associated gray matter are part of a major subdivision of the brain collectively called (what?).


12. Which nerve controlling extraocular muscles has been cropped out?

occulomotor (III)

13. Your animal care protocol is approved. You have your anesthetized rat in the stereotaxic device and you have exposed bregma and lamda. What else do you need to aim an electrode tip to the ventromedial nucleus of the hypothalamus?

a rat brain atlas

14. How come you do not have spongiform encephalitis even though you have the protein in your brain, and even though you could contract spongiform encephalitis if exposed to tissue from a person or animal that does?

the protein would need to be changed to the diseased configuration (scrapie) from the normal configuration (control)

15. You are looking at the outside of the brain. Name a structure from the prosencephalon that you cannot see.

basal ganglia (any of them), hippocampus, internal capsule

16. 'The cranial nerves have sensory and motor functions. Regarding motor functions, they can be either for the (list both) motor systems."

autonomic & somatic

17. "The thalamus is a 'relay' for " Complete that sentence for both general functions.

sensory and somatic motor

18. Regarding receptive field, answer either (1) Why is the Pacinian corpuscle's receptive field the largest? Or (2) What units would you use to describe the receptive field of a touch receptor?

deeper in the skin, a greater area of deformation would stimulate it; square mm

19. Under what normal circumstance would your receptors that are specifically responsive to vibration be stimulated?

20. Gamma motor neurons (the fusimotor system) connects to (answer either) (1) What? Or (2) For what purpose?

intrafusal muscle, preset the stretch of the stretch receptor

21. For capsaicin, answer either (1) What does the receptor look like (molecularly)? (2) What would be the more normal way to stimulate this molecule? or (3)Tell where (or how) this type of receptor was first found.

a channel, heat, transient receptor potential phenotype of Drosophila led to mating defect

22. "In conclusion, a pain receptor is a chemoreceptor for (name a chemical)."

histamine, acetylcholine, serotonin, bradykinin

23. In the lemniscal system, a sensory receptor in the lower part of the body makes its first synapse (where)?.

gracile nucleus

24. In the sense of touch, neural processing takes place to sharpen spatial localization of the stimulus. What kind of neural processing?

lateral inhibition

25. As described by dermatomes, sensory receptors in the legs input to sacral and (what?) parts of the spinal cord.


26. For the touch input from the face that travels in the medial lemniscus, answer either (1) What is the cranial nerve for input? Or (2) What is the specific part of the thalamus for synapses?

trigeminal (V), VPM

27. A cell in the dorsal horn of the gray matter of the spinal cord carries pain and temperature information to (where is the first synapse in?) the brain.

VPL (thalamus)

28. You were introduced to the term "neospinothalamic" whose input is from A-delta fibers. In comparison, answer either (1) What slower fibers have input for the more evolutionary ancient system? Or (2) What is this more ancient system called?

C fibers, paleospinothalamic

29. In general, pain from the lower body goes in the anterolateral system with (what exception?). [Note, the question still applies to the lower part of the body, i.e., not the face.]

from the viscera, via dorsal columns

30. Heart rate and blood pressure are changed substantially when a person dives into water. These changes can be mediated by fairly minimal stimulation with water. Answer either (1) What is that minimal part of the body that needs to be stimulated? Or (2) What is the nerve that carries that information to the brain?

face, trigeminal (V)

31. Compare the two-point discrimination threshold for the tongue vs for the forearm.

way smaller for tongue

32. Where did the Raphe nucleus get the sensory information to feed out to the cell in the dorsal horn of the gray matter of the spinal cord?

any of these will do: Somatosensory cortex -> amygdala and hypothalamus -> midbrain periaqueductal gray

33. How does the G protein coupled receptor known as rhodopsin come to be bound to all-trans retinal?

after light stimulated the 11-cis

34. Regarding the energy of a photon, answer either (1) What is the equation? Or (2) What are the units energy for the answer (3.96 x 10-12 [for 500 nm light])?

E = hv (that v is a nu), ergs

35. In addition to refractive correction for myopia (glasses or contact lenses) name one of the two treatments used to correct myopia in the last 20 years.


36. Everybody should get tested for glaucoma regularly. Answer either (1) What is being measured? Or (2) Why, if left untreated, would glaucoma lead to blindness?

pressure of the eyeball, ganglion cells die

37. When the zonule fibers (suspensory ligaments) are relaxed, answer either (1) What is the state of the ciliary muscle? Or (2) For what type of vision is the lens accommodated?

contracted, close

38. How come a young person with autosomal dominant retinitis pigmentosa (a rhodopsin missense mutation) still has rod-mediated vision?

the recessive allele still mediates transcription of a functional rhodopsin

39. People with retinitis pigmentosa develop "tunnel vision." Answer either (1) What does this mean? Of (2) Why is that the visual impairment of this disorder?

they are blind in a ring around the center (ring scotoma), loss of rods

40. For age-related macular degeneration, answer either (1) What specific aspect of vision is lost? Or (2) When does it usually occur?

cone vision, around age 80

41. Concerning the extraordinary sensitivity of rods, answer either (1) Why can you conclude that a rod can "see" one photon if it takes 6-14 photons absorbed by rods to see? Or (2) How did Hecht, Schlaar and Pirenne do this landmark study?

those fall on 500 rods so one rod virtually never gets more than one, psychophysics

42. In addition to housing the melanin that keeps light from reflecting around the inside of the eye, name one of the functions of the retinal pigment epithelium (RPE) in maintaining the health or function of the rod outer segment.

phagocytose shed rod tips, provide ii-cis retinal

43. The mechanism by which one gene (for long wavelength cones in New World monkeys) became the yellow-green cone rhodopsin pair (in Old World monkeys) is the general mechanism for the origin of the G protein coupled receptor superfamily. How did one gene become two?

unequal crossing over in meiosis

44. By their very nature, fluorescent lights go on and off with alternating current. Why don't you notice this?

above flicker fusion frequency (visual receptors are slow

45. For the phosphodiesterase in visual transduction, answer either (1) What is directly upstream? Of (2) What is directly downstream?

transducin, channel (cGMP)

46. For the extracellular space outside the rod, answer either (1) Why is there a current from inner to outer segment? Or (2) When is there a current from inner to outer segment?

ions are pumped from the inner segment while channels are in the outer segment, in the dark

47. Occasionally I pointed to how uninteresting the wall was vs the perceptual richness of the map on the wall. Say something about how the receptive field organization in the lateral geniculate nucleus contributes to this difference.

center surround influences contrast

48. What is the most obvious thing that happens between the pretectum and the Edinger-Westfall nucleus?

goes bilateral

49. Concerning layers in the lateral geniculate nucleus, answer either (1) What is the main difference between layers 1, 4, & 6 vs 2, 3, & 5? Or (2) What is the main difference between layers 1 & 2 vs 3 to 6?

1,4,6 contralateral, 1, 2 magnocellular

50. In the "movie" of Hubel and Wiesel's simple cell experiment, how come a wide line of light projected right on target did not elicit firing while a thin line, also accurately aimed, did?

wide hit inhibitory surround also

51. An oblique electrode track traverses several millimeters of the visual cortex. What change do you notice about the receptive field properties of the firing neurons you encounter?

one yey -> both -> other, (also angle of line)

52. A radioactive amino acid was injected into one eye. Say one of the several cell biological events that must occur to give an autoradiogram of ocular dominance columns. (I am not asking how to do autoradiography.)

is put into protein, is transported down axon, is transported across synapse, transported down other axon

53. Why did I tell the story of geese following the Nobel prize winning ethologist Konrad Lorenz in the context of the visual cortex?

sensitive (critical) period

54. Two tuning forks give 5 beats per second if you listen with one ear. Under what circumstances would you hear beats if you held each near opposite ears? (Assume you cannot hear either with the ear on the other side.) Alternatively answer this: What theory does this phenomenon of binaural beats support?

low frequency, Rutherford telephone theory

55. Imagine that you have come up with a nearly magical technique to record and graph the responses of an auditory hair cell as a function of frequency. How would that graph compare with a similar presentation of the tuning curve of a cell in the primary auditory cortex?

much wider on the frequency axis

56. Why is it important that auditory receptor cells have voltage-gated calcium channels?

for release of transmitter vesicles

57. What is the difference between a kinocilium and stereocilia?

kino is real cilium with 9 plus 2, stereocilia are not

58. Where (if at all) does the auditory input (from one ear) become bilateral?

superior olive

59. Otoconia are used Answer either (1) in what structures? Or (2) to stimulate what kind of cells?

utricle and saccule, hair cells

60. Information from the vestibular system integrates with information (from what major brain structure?) for the vestibulospinal tract.


61. What is the significance of a comparison of PTC sensitivity alleles in primates, people of sub-Saharan Africa, and all other people?

that polymorphism originated early but after primates, but only people with taster and non-taster came out of Africa to populate the world

62. For the TRPM5 channel used in taste, answer either (1) what flows through this channel? or (2) What is the ligand for this channel?

calcium ions, IP3

63. Relative to all the other G protein coupled receptors we have discussed in this course, what is unusual about the ones for sweet and umami?

they are dimers

64. For taste, give the name of the nucleus or the location of nucleus that feeds to the VPM (ventral posterior medial) nucleus of the thalamus.

solitary nucleus in brainstem

65. Here's a partial list of nerves that carry taste and spice information from the mouth: V, IX, & X. Give the name or number of the one I left out.

VII facial

This page was last updated 3/25/09

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