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BIOL-415 Nerve cell mechanisms in behavior

BIOL-615 Neural bases of behavior

Final exam - Thursday, May 7, 2009 - Prof. Stark

All questions are short answer. 65 points total.

 

1. Suppose your research isolated the receptor molecules for ³putrid² and ³aromatic.² Answer either (1) Characterize these molecules molecularly. Or (2) How do they differ from eachother?

 

G protein coupled receptors, their sequences are different especially in particular locations

 

2. Relative to visual and auditory receptor cells, what is the notable difference in the life expectancy of olfactory (and gustatory) receptor cells?

 

Taqste and smelol receptor cells die and get replaced

 

3. In what way does the cAMP made by adenylate cyclase under the command of Golf function like cGMP in rod cells?

 

It is a ligand affecting the channel from inside the cell

 

4. Taste projected near to where the tongueıs somatosensory representation was on cortex. Relate this to the situation for olfaction.

 

Smell, by contrast, projects to a deep, dark, mysterious assortment of places, the limbic system

 

5. Binding to troponin, helping with the release of vesicles at the ³presynaptic² membrane of the neuromuscular junction, release from sarcoplasmic reticulum. Name a yet one additional location or channel for the action of calcium ions in excitation – contraction coupling.

 

T-tubules carry action potentials into cell with DHP calcium channels

 

6. The numbers 13 vs 1730 were given for extraocular vs gastrocnemius muscles respectively (and explained in terms of muscles for fine vs gross movement respectively). 13 and 1730 what?

 

Number of muscle cells (fibers) per motor unit (one spinal motor neuron)

 

7. For a Golgi tendon organ in the tendon of the biceps, answer either (1) How would the muscle react from stimulation? Or (2) What is the sensory afferent axon?

 

Muscle is inhibited from contracting (via inhibitory interneuron); Ib

 

8. How is it that, in the knee-jerk reflex, the flexor is inhibited from contracting?

 

Through an inhibitory interneuron

 

9. I have located a spinal motor neuron for the triceps in the ventral horn. Where should I look, relative to that cell, for neurons that would mediate making a fist?

 

(using that diagram of making a muscle superimposed on the ventral gray matter) lateral to that neuron

 

10. In the sheep brain dissection, we peeled off the brachium pontis to the ventral midline. There we (presumably) saw (what tract?).

 

pyramidal (corticospinal)

 

11. A lesion halfway across the spinal cord would lead to a motor loss below the lesion on which side (use the appropriate term)?

 

ipsilateral

 

12. Voluntary output to the upper and lower part of the face differs in what fundamental (neurological) way?

 

Upper-bilateral, lower only contralateral

 

13. Name a brain location other than the motor cortex that sends a motor tract down the spinal cord.

 

Reticular formation, vestibular nucleus, red nucleus, superior colliculus

 

14. In terms of the cortical motor map of the face, rationalize why it is as extensive as the corresponding sensory representation of the face.

 

There are many muscles mediating many expressions

 

15. Regarding caudate and putamen, answer either (1) They get input from (what major area?) in addition to the substantia nigra? Or (2) In addition to the pars compacta and the substantia nigra, their output is to (where?)?

 

cerebral cortex, VA/VL thalamus

 

16. ³In a sense, Huntingtonıs is the opposite of Parkinsonıs.² Rationalize this statement on the basis of either (1) thalamic input to cortex, or (2) behavior of the afflicted person.

 

Excitatory input to cortex is lower in Parkinsonıs, explaining hypokinesia, higher in Huntingtonıs explaining choreo-athetosis

 

17. Dorsal nucleus of Clarke, inferior olive, vestibular nuclei – this is an incomplete list of brain stem areas that feed to the cerebellar cortex. Complete the list (one more item).

 

Pontine nuclei relay information from cerebral cortex

 

18. Regarding the Purkinje cell, answer one of these: (1) What is the nucleus it outputs to? (2) What cell makes numerous inputs to each Purkinje cell? Or (3) What cell has one-on-one input to the Purkinje cell?

 

Deep cerebellar nuclei, granule cell (parallel fibers), climbing fiber

 

19. In the time since the stem cell debate was in the forefront the federal administrative scrutiny, what advancements have lessened the ethical dilemma?

 

There are sources of stem cells other than embryonic

 

20. In what fundamental way are bicoid and kruppel different in the locations where their genes act?

 

Bicoid mother (³maternal²), kruppel embryo (³zygotic²)

 

21. Say something about the comparison of ras with a heterotrimeric G protein.

 

Ras is a G protein, smaller, monomeric

 

22. Several signaling ligands were introduced to you: retinoic acid, wingless, fibroblast growth factor, bone morphogenetic factor and sonic hedgehog. Which pathway most closely approximates the one initiated by bride of sevenless and why?

 

FGF b/c it is membrane receptor tyrosine kinase signaling through ras and MAPK

 

23. In between ectoderm and the neural groove are cells whose fate is very different from those of the neural groove. In what way?

 

Neural crest will become components of peripheral n.s.

 

24. Here is a list of cell types: sensory neuron, melanocyte, adrenergic sympathetic neuron, cholinergic sympathetic neuron, and chromaffin cell. Answer either: (1) What is the common ancestor? Or (2) How is it that they assumed different fates?

 

Neural crest progenitor, ³growth factors² (NGF, LIF, glucocorticoids, etc.)

 

25. Embryologists tell us that the retina and optic ³nerve² are part of the central nervous system. So you were told earlier. Now add some details that justify that position.

 

Optic vesicle becomes optic cup, outpocket from diencephalon

 

26. Sperry proposed neurobiotaxis for how each optic nerve found the right address in the tectum. What had been the previous thinking?

 

Weiss, resonance, connection from eye assigned function of central cell

 

27. Several times, the neuromuscular junction was used as a model system in development and ³learning.² Where did agrin fit into the discussion?

 

Agrin mediates the localization of acetylcholine receptors to the end plate

 

28. In a comparison of spinal motor neurons on the normal side vs the side where a second limb bud had been transplanted, how does apoptosis apply?

 

There would be zillions of spinal motor neurons, decreased by apoptosis on the basis of limited target

 

29. Describe the geometry of the TrkA receptor for nerve growth factor.

 

It is a single membrane passing enzyme that dimerizes on binding the ligand

 

30. ³Hold that thought.² How did Donald Hebb propose that was achieved in the 1940ıs?

 

reverberating circuits of neurons with excitatory connections with each other

 

31. Why would a congenital cataract in one eye need to be treated quickly?

 

Appropriate development/maintenance of binocularly innervated cells in the visual cortex requires patterned vision from both eyes

 

32. Food can be repeatedly paired in classical and instrumental conditioning. How does the presentation of food differ in these two models of associative learning?

 

Classical, food is unconditioned stimulus paired with conditioning stimulus (bell), instrumental (operant) food is positive reinforcing stimulus paired with behavior (bar press)

 

33. Why is habituation of the gill withdrawal considered to be a simple model of learning instead of sensory adaptation or muscle fatigue?

 

It is change in synapse, not sensory receptor or muscle

 

34. In the difference between the shortest term ³learning² and long term sensitization in Aplysia, why was ubiquitin hydrolase found to be useful?

 

Mediates longer term activation of PKA by targeting the inhibitory subunits for degradation

 

35. In a study of long term potentiation, a Schaffer collateral is stimulated repeatedly while recording from a CA1 pyramidal cell. Answer either (1) What changes? Or (2) What is the control?

 

The response of the CA1 cell gets bigger, but not for stimulation of another collatoral that had not been repeatedly stimulated

 

36. In a study of long term depression in Purkinje cells, how is the sensitivity of AMPA receptors decreased?

 

Receptors got internalized (pulled from membrane)

 

37. An old term, still used, for all the cerebral cortex excepting the primary sensory and motor areas.

 

Association cortex

 

38. Draw how a contralateral neglect syndrome patient behaves on a ³bisect the line² task.

 

A big horizontal line will not be divided in the middle, but way to one side

 

39. How come you can show something to someone with a severed corpus callosum severed and have that information go to only one hemisphere?

 

If they fixate on one side of the stimulus, image goes to one temporal retinal field and the other nasal retinal field that project ipsilateral to the temporal retinal presentation

 

40. How would you know if a subject is in stage I, II, III, or IV sleep?

 

On the basis of EEG, slow waves for deep sleep

 

41. For REM sleep, what happens to the electroencephalogram (EEG)?

 

Becomes like EEG of awake, aroused subject

 

42. Say something (anything) about drusen – Where are they located (what layer, if cellular, what cell)? Who has them?

 

Between RPE and Bruchıs membrane, extracellular deposits, AMD patients

 

43. Youıre 80 and your ophthalmologist says you are beginning to show signs of AMD (age-related macular degeneration) so (s)he gives you an Amsler grid to hang on your refrigerator where you will see it daily. Draw how it looks and how this is altered if you need immediate attention.

 

Look like graph paper, change to having dot and distorted lines at center

 

44. A laser blasts a blood vessel in photocoagulation. What is different about how a laser is applied in photodynamic therapy?

 

Light activates chemical (drug) in blood vessel

 

45. Explain why most people want to stay up late and get up late in terms of a ³rule² proposed by a famous circadian biologist.

 

Human (diurnal animal) circadian rhythm is longer than 24 hours according to Ashoffıs rule

 

46. In a neurochemical circuit initiated by the serotonin and norepinephrine secreting parts of the brain, motor neurons are inhibited during sleep with what spinal cord inhibitory transmitter?

 

glycine

 

47. Say something (anything) about melanopsin, What animals have it? What cells have it? Why is it called ³melanopsin?²

 

frogs have it in skin mediating melanin dispersal, in ganglion cells of mammals to mediate entrainment

 

48. Mutant SOD (superoxide dismutase) can cause Lou Gehrigıs disease without affecting enzymatic activity. Give a possible reason.

 

Might aggregate, might interfere with proteasome, might interfere with dynein (retrograde axonal transport), ER stress, interfere with translation

 

49. In what cells other than neurons might mutant SOD lead to death of spinal motor neurons?

 

glia

 

50. State one drug or molecular treatment that may help in the treatment of Lou Gehrigıs disease.

 

Resveratrol (red wine), VEGF, IGF, stem cells, RNAi, Riluzole (decrease glutamate release)

 

51. Inhibition from the cortex prevents sham rage mediated by output from the reticular formation. What additional part of the brain was shown in Bardıs research to be central to this pathway?

 

hypothalamus

 

52. A person has an asymmetric smile if you ask him or her to smile. Under what circumstances might (s)he have a symmetric smile?

 

Make him or her laugh

 

53. Acting through the hypothalamus, the amygdala activates one of the bodyıs classic hormonal responses to stress. What hormone?

 

corticosteroid

 

54. Long term potentiation (LTP) in the amygdala is a mechanism mediating fear conditioning in classic experiments in which what stimulus is paired with what other stimulus?

 

Tone paired with shock

 

55. Patient SM has Urbach-Wiethe syndrome that caused bilateral destruction of the amygdala. In terms of recognition and drawing of facial expressions, what was her specific and unusual deficit?

 

Could not draw or recognize fear

 

56. Where does estradiol bind in the brain?

 

All over, but strongly in hypothalamus

 

57. Human metabolism creates cholesterol. Insect canıt do this. Why would cholesterol be an essential nutrient if the body could not biosynthesize it?

 

Precursor of steroid hormones

 

58. Why would hyperplasia of the adrenal cortex lead to masculinization of a female?

 

Adrenal cortex makes androgens that act like testosterone

 

59. The Mullerian ducts degenerate and the Wolffian ducts are supported. Answer either (1) What could lead to this? Or (2) What is the result?

 

Wolffian ducts become epididymus, seminal vesicles etc, sexual differentiation of male

 

60. In his studies of the interstitial nucleus of the anterior hypothalamus (INAH), why did Simon LeVay feel the need to include a control group of heterosexuals who had died of AIDS?

 

Because most of his male homosexual subjects had died of AIDS

 

61. Hippocampal lesions interfered with performance on the radial 8 arm maze. Why was the memory this task tapped into called ³working memory?²

 

If rat can scurry to all 8 arms without repeating one, it must remember a map short term

 

62. What does learning a mirror-drawing task say about Brenda Milnerıs famous patient HM who had bilateral hippocampal lesions?

 

Non-declarative task while declarative memory is lost

 

63. Rationalize why I was so dogmatic to say that mRNA must be involved in consolidation of long-term memory.

 

Only a structural change, like in synapse efficiency, could endure and that would require protein synthesis

 

64. Mice were trained but before the memory could form, puromycin in the hippocampus interfered. What a disappointment when the mice exhibited memory when the puromycin was washed out! If it did not block consolidation, what could puromycin have blocked?

 

Should have blocked consolidation by blocking protein synthesis, but memories formed so it must have interfered with retrieval

 

65. Nobelist Roger Sperry was optimistic that people have free will even though materialistic science should dictate determinism. How did he rationalize this optimism?

 

Although physical laws still apply, emergent properties of assembled systems have awesome possibilities