Neuroscience and Psychology

1. You are studying electrical synaptic transmission in Aplysia. You place a stimulating electrode into neuron A and recording electrodes in neurons A, B and C; as shown in the diagram. a. What are the labels referencing in the diagram? i. Arrow (1): ii. Bracket (2): iii. Arrows (3): b. You inject a depolarizing current into neuron A, not strong enough to generate an action potential, and record the following voltage outputs (right) from neurons A and B. What is this passive change in voltage/depolarization called? c. What does it mean that electrical transmission is graded? How might you demonstrate this property using the experimental set-up described above? d. We add a stimulating electrode into neuron B and inject depolarizing currents into both neurons A and B simultaneously (same strength as above), but this time it causes neuron C to fire an action potential. What property of electrical signaling caused neuron C to reach threshold and fire an action potential? e. We remove the stimulating electrode from neurons A and B, placing one into neuron C. Next, we inject a depolarizing current into it, the same strength that was injected in section b. Which of the following (left, middle, right) would you expect to record from neurons A and B? Why? 2. You want to try the same experiments you did in Aplysia at the frog neuromuscular junction. You place a stimulating electrode in the presynaptic terminal and recording electrodes at various points along the motor end plate, as shown in the diagram below. a. What are the arrows pointing to in the diagram? b. You stimulate the presynaptic terminal, depolarizing the motor end plate above threshold (suprathreshold). i. What is this change in voltage/depolarization called? ii. Which of the following (left, middle, right) best illustrates the expected voltage recordings from the motor end plate electrodes? c. You add curare to the bath and repeat the stimulation of the presynaptic terminal, depolarizing the motor end plate. i. What is this change in voltage/depolarization called? ii. Which of the following (left, middle, right) best illustrates the expected voltage recordings from the motor end plate under this condition? d. You notice that there is a gap in time between the stimulation of the presynaptic terminal and depolarization of the motor end plate. i. What is this gap in time called? ii. What causes it? iii. Why did you not notice this gap with the Aplysia experiment? iv. If you decreased the temperature of the bath, what would happen to this gap in time? e. You take a break from your experiment, removing the stimulating electrode from the presynaptic terminal, but leave the recording electrodes in the motor end plate. When you get back from lunch, you see lots of “noise” on your tracings, as illustrated below. You take them to Dr. Wilhelm, who reminds you that this is not noise, in fact these are to be expected. i. What are these changes in voltage/depolarizations called? ii. What causes them? iii. Why are they not seen in the voltage tracing from electrode (D)? 3. Cesare Montecucco first described the mechanisms for two zinc protease neurotoxins that impact transmitter exocytosis. a. What are the names of these two toxins? b. These toxins have the same molecular mechanism (cleavage of SNARE proteins, preventing neurotransmitter release); yet one causes flaccid paralysis while the other causes spastic paralysis. Describe why this is the case. 4. Neurons integrate excitatory and inhibitory signals from multiple sources, influencing their ability to generate an action potential. Illustrate voltage tracings for the following: a. Two EPSPs of equal magnitude occurring simultaneously at different sites i. What is this called? b. Two EPSPs of equal magnitude occurring in rapid succession at the same site i. What is this called? c. An EPSP & IPSP of equal magnitude occurring simultaneously at different sites d. Two EPSPs of equal magnitude occurring at different times and different sites e. This concept will be on your test- make sure that you understand synaptic integration! 5. You are investigating the function of 2 different neuronal GPCRs, GPCR-1 and GPCR-2, that bind the same ligand and have effects on adenylyl cyclase activity. a. After adding ligand to the receptors, you find opposing effects on adenylyl cyclase activity: GPCR-1 increases AC activity but GPCR-2 decreases it. Based on these findings, what type of G protein is activated by each receptor? b. You find a drug that is a positive allosteric modulator of GPCR-2. On the graph below, draw bars indicating the theoretical change in cAMP levels for each condition indicated (exact values not important). c. You have collaborated with molecular and cellular biologists to express each receptor in a neuronal cell culture and induce mutations in components of the GPCRs and G proteins. You add the GPCR ligand to the cell cultures and measure levels of cAMP in response. For each condition below, indicate whether you expect higher or lower cAMP levels compared to cAMP levels produced by the normal, unmutated GPCR. i. Mutation in the ligand-binding domain of GPCR-1, preventing the conformational change of the receptor in response to ligand binding ii. Mutation in the G protein-binding domain of GPCR-2, preventing binding of the G protein to the receptor iii. Mutation in the Gα subunit of Gi that prevents release of bound GDP iv. Mutation in the Gα subunit of Gs that prevents GTP hydrolysis v. Mutation in the C-terminus of GPCR-2 that prevents phosphorylation of this site by G protein receptor kinases d. An immunologist has uncovered a new toxin isolated from a species of pathogenic fungi that she believes may interfere with signaling of your ligand and GPCRs. You generate the data shown below, measuring cAMP levels in cells expressing both GPCR-1 and GPCR-2, with and without the toxin added. i. How does the toxin affect activity of adenylyl cyclase? ii. Hypothesize two different mechanisms that may explain how the toxin acts to produce this data. (e.g., the toxin blocks X, which leads to Y, causing the effect on cAMP levels shown here). iii. You have cells expressing only GPCR-1, a way to measure cAMP, and the toxin. What is an experiment you could perform to differentiate between the two mechanisms you proposed? What would the expected results be to support one mechanism over the other? 6. The nicotinic acetylcholine receptor is found in both muscle and neuron. The muscle nAChR is _____-meric (meaning it has ___ subunits) with ___ acetylcholine binding sites. The subunit composition of the muscle nAChR is different from the neuronal isomers. One uniting feature is that they are all ionotropic, meaning they have a ___ at the center of the protein that allows passage of ___ ions into the cell and ___ ions out of the cell, down their respective electrochemical gradients. a. We added nicotine (nAChR agonist) to a bath surrounding a frog neuromuscular junction and recorded depolarization of the motor end plate. While doing single channel recordings, we noticed that after opening for a short period, some of the receptors stopped conducting. After 5 sec, most of them started working again. What made them stop conducting ions? b. We then added acetylcholine to the bath, but did not detect a change in the membrane potential, which seems to be “stuck” at +20mV. i. What is causing this? ii. What 2 steps must occur to fix it? 7. When conducting a current clamp experiment using the giant motor synapse in the crayfish, you place a current injecting electrode and a recording electrode into the lateral giant fiber and a current injecting electrode and a recording electrode into the giant motor fiber (as shown in panel A above). a) You inject a current into the current injecting electrode in the lateral giant fiber that causes a recorded depolarization of the membrane as measured by your recording electrode in the lateral giant fiber. i) Draw a graph in which you depict this graded potential as recorded by the electrode in the lateral giant fiber. Make sure to label the x- and y-axes appropriately and include the timing of the current injection in your graph. ii) Draw a graph in which you depict the membrane potential recorded by the recording electrode in the giant motor fiber. Make sure to label the x- and y-axes and include the timing of the current injection. iii) Explain the graphs for i) and ii) above- what did you depict and why? b) You inject a current through the current injection electrode in the giant motor fiber and record a depolarization of the membrane as measured by the recording electrode in the giant motor fiber. i) Draw a graph in which you depict this depolarization as recorded by the electrode in the giant motor fiber. Make sure to label the x- and y-axes appropriately and include the timing of the current injection in your graph. ii) iii) Draw a graph in which you depict the membrane potential recorded by the recording electrode in the lateral giant fiber. Make sure to label the x- and y-axes and include the timing of the current injection. Explain the graphs for i) and ii) above- what did you depict and why? 8. Vesicle exocytosis is the process by which neurotransmitters are released from presynaptic axon terminals. Using the word bank below, fill in the blanks for each passage about the vesicle cycle. Not all words will be used and some may be used more than once [listed twice as (1) and (2)]. Kiss-and-Run Recycled Fusion NSF Munc13 (1) CREB Docking Syntaxin SNAP Munc13 (2) Cooperativity Endosome Zippering SNAP-25 Complexin (1) Priming Clathrin Plasticity Rab Proteins Complexin (2) Synaptotagmin Filling RIM proteins Vesicle Munc18 (1) Clathrinmediated Endocytosis Synaptobrevin Bulk Endocytosis Ultrafast Endocytosis Munc18 (2) Tethering and ___(1)___ involve formation of physical links between the vesicle and the membrane, mediated by binding of ____(2)____ on vesicles to ____(3)____, which are tethered to Ca2+ channels on the presynaptic membrane. Also during this process, ___(4)___ binds to syntaxin to prevent formation of the SNARE complex. ___(5)___ is an ATP-dependent process that allows vesicle fusion with the membrane. First, ___(6)___ hydrolyzes the ATP to prepare the SNARE proteins. Next, ___(7)___ interacts with RIM proteins and ___(8)___ is phosphorylated, allowing syntaxin to enter its open state. Subsequently, the vesicular SNARE protein, ___(9)___, assembles together with the T-SNAREs, ___(10)___ and ___(11)___, to form the partially-zippered SNARE complex. ___(12)___ is bound to the SNARE complex, preventing complete formation so there is no spontaneous neurotransmitter release. ___(13)___ is the Ca2+-dependent process that enables merging of the vesicle with the presynaptic membrane, exocytosing vesicular contents. The Ca2+-sensor for this process, ___(14)___, is present on the ___(15)___. This protein can bind multiple Ca2+ ions, with each ion bound increasing the likelihood of transmitter release in an example of ___(16)___. The Ca2+-sensor, once bound by Ca2+, forces the vesicle and synaptic membrane closer together. This is accompanied by partial dissociation of ___(17)___ from the SNARE complex that allows full ___(18)___ of the complex and subsequent membrane fusion and transmitter release. There are multiple methods by which vesicles may be ___(19)___. One way is through rapid, incomplete fusion that may occur during conditions of high Ca2+ called ___(20)___. The most rapid pathway is called ___(21)___, occurring just after fusion between the active and periactive zones. A slower method occurs through binding of the protein ___(22)___, triggering formation of a pit in the readily retrievable pool. This is called ___(23)___. Finally, in situations of high activity, slower methods may not be able to keep up with recycling needs. So, the membrane will undergo ___(24)___, which involves formation of an ___(25)___ that is taken up in a large “chunk.” 9. Not all synapses are excitatory. In fact, inhibitory and modulating synapses can have profound impacts. Describe how an inhibitory axo-axonic synapse may impact neurotransmission at a glutamatergic (glutamate-releasing/excitatory synapse): 10. What is the experimental evidence that spontaneous miniature end plate potentials (mEPPs) are produced by the release of many molecules of acetylcholine, rather than a single molecule of acetylcholine? 11. Why does transmitter release continue to occur after blocking presynaptic sodium channels with the toxin TTX (which blocks the presynaptic action potential) and experimentally depolarizing the nerve terminal? 12. What is the difference between direct and indirect actions of receptor activated G proteins on ion channels? Provide one example of a direct action of a G protein on an ion channel and one example of an indirect action of a G protein on an ion channel. 13. How is cAMP used as a second messenger in indirect actions of metabotropic receptors? 14. List four factors that determine how a cell responds to binding of a neurotransmitter to its receptor. 15. Explain why synaptic interactions mediated by indirect mechanisms typically develop more slowly and last much longer than those mediated by direct mechanisms 16. How do calcium ions trigger synaptic vesicle exocytosis? 17. What is the experimental evidence that synaptic vesicles actually fuse with the plasma membrane during transmitter release? 18. Describe the different functions for presynaptic vs. postsynaptic inhibition. 19. Explain how G protein-coupled receptors become activated after binding neurotransmitter ligand? Include explanations and specific examples for Gs, Gi, Go, and Gq. 20. We classified vesicles into 3 pools in the presynaptic terminal. Name each pool and hypothesize/describe a situation that would trigger that pool’s release at the NMJ. 21. For the following statements, indicate the following: I: Statement A will result in an increase in Statement B D: Statement A will result in a decrease in Statement B N: Statement A will have no effect on Statement B ___ A. Inhibition of munc-18 function B. SNARE complex formation ___ A. Presence of curare at the neuromuscular junction B. Action potential amplitude at the neuromuscular junction ___ A. Acetylcholine binding the the M2 muscarinic acetylcholine receptor B. Neuronal excitability ___ A. Norepinephrine binding to the β1 adrenergic receptor B. Protein Kinase A activation ___ A. Norepinephrine binding to the α1 adrenergic receptor B. K+ permeability ___ A. Activation of the phospholipase C pathway B. PIP2 levels ___ A. Blockage of voltage-gated Ca2+ channels B. Neurotransmitter release ___ A. Increased Ca2+ entry into the presynaptic terminal B. GCamP fluorescence signal ___ A. Sugar consumption B. Ca2+ levels in taste bud cells ___ A. Binding of a positive allosteric modulator to a GPCR with the ligand B. GPCR activity ___ A. Neuronal activity, increasing extracellular K+ concentration B. Astroglial membrane potential 22. What is the approximate resting membrane potential for an astrocyte? Why is it different from the neuronal resting membrane potential? 23. What is the functional significance of the GTPase activity in the alpha (α) subunit of a G protein? 24. Norepinephrine is a unique neurotransmitter to study, as it has 4 receptors (α1, α2, β1, and β2) capable of coupling to the 3 main types of G proteins (Gs, Gi, and Gq). a. Illustrate the pathways for Gs and Gi after binding of norepinephrine. i. ii. iii. Ascribe the correct receptor(s) to each pathway (one or more receptors may not be used, since it is Gq coupled). Include the effectors and second messengers For each pathway, indicate the net/overall impact on ion channels and ion levels in the neuron. 25. Neurotransmitter release is proposed to follow the Quantum Hypothesis. a. Define what is meant by “quantum hypothesis.” b. How many vesicles are in a single quantum? c. In your own words, what is quantal size? What is one way that quantal size can be changed? d. In your own words, what is quantal content? What is one way that quantal content can be changed? e. In an individual with hypocalcemia (low Ca2+), what effect would this have on quantal size at the NMJ? What about quantal content? f. Is the quantum content the same or different at different types of synapses? Provide examples and explanations. 26. You are comparing the neuromuscular junction from a patient with LEMS, a condition in which they have auto-antibodies against presynaptic vg-Ca2+ channels (which will block these channels) to a patient with a condition MG in which they have auto-antibodies against nAChR (which will block this receptor). Answer LEMS, MG, Neither, or Both to the following statements. a. If you depolarized the presynaptic terminal to stimulate ACh release, which would you expect to have a normal EPP? b. If you added physiologic levels of ACh to the NMJ, which would you expect to have a normal EPP? c. If you added botulinum toxin to the NMJ, which would you expect to have a normal EPP? 27. Ca2+ was a recurring element across this part of the course: from glia, to its function as a second messenger, and its role in neurotransmitter exocytosis. Answer the questions below regarding Ca2+ handling in the cell and its important contributions to these processes. a. Name 2 ways that Ca2+ can enter the neuron cytoplasm from outside the cell or from intracellular stores. b. Why is it necessary to control Ca2+ concentrations at “rest”? c. Name 2 methods the cell uses to keep cytoplasmic Ca2+ concentrations low. d. Describe 1 way in which Ca2+ acts as a second messenger. e. Describe one method in which scientists can monitor Ca2+ concentrations in a cell experimentally. f. Describe at least one method scientists could use to control Ca2+ concentrations in a cell experimentally. 28. Two types of neurotransmitter receptors: ionotropic and metabotropic. a. Describe at least TWO structural differences between ionotropic and metabotropic receptors. Make sure you describe how each receptor exemplifies this difference. b. For the two structural differences above, describe how each of these account for a functional difference in the receptors. c. Crystal structures of the muscarinic and nicotinic acetylcholine receptors are shown below. Using your knowledge of their basic molecular structure, correctly label each receptor. 29. Virchow first described glial cells as “nerve glue.” Since then, numerous different glial cells functions have been discovered. Complete the table below, describing the key functional role(s) for each glial cell type. Glia Type Ependymal Cells Radial Glia Oligodendrocytes Schwann Cells Microglia Astrocytes Embryonic Origin Location (CNS/PNS) Function(s)

As we begin this session, I would like to take this opportunity to clarify my expectations for this course:

Please note that GCU Online weeks run from Thursday (Day 1) through Wednesday (Day 7).

Course Room Etiquette:

It is my expectation that all learners will respect the thoughts and ideas presented in the discussions.
All postings should be presented in a respectful, professional manner. Remember – different points of view add richness and depth to the course!

Office Hours:

My office hours vary so feel free to shoot me an email at [email protected] or my office phone is 602.639.6517 and I will get back to you within one business day or as soon as possible.
Phone appointments can be scheduled as well. Send me an email and the best time to call you, along with your phone number to make an appointment.
I welcome all inquiries and questions as we spend this term together. My preference is that everyone utilizes the Questions to Instructor forum. In the event your question is of a personal nature, please feel free to post in the Individual Questions for Instructor forumI will respond to all posts or emails within 24 or sooner.

Late Policy and Grading Policy

Discussion questions:

I do not mark off for late DQ’s.
I would rather you take the time to read the materials and respond to the DQ’s in a scholarly way, demonstrating your understanding of the materials.
I will not accept any DQ submissions after day 7, 11:59 PM (AZ Time) of the week.
Individual written assignments – due by 11:59 PM AZ Time Zone on the due dates indicated for each class deliverable.

Assignments:

Assignments turned in after their specified due dates are subject to a late penalty of -10%, each day late, of the available credit. Please refer to the student academic handbook and GCU policy.
Any activity or assignment submitted after the due date will be subject to GCU’s late policy
Extenuating circumstances may justify exceptions, which are at my sole discretion. If an extenuating circumstance should arise, please contact me privately as soon as possible.
No assignments can be accepted for grading after midnight on the final day of class.
All assignments will be graded in accordance with the Assignment Grading Rubrics

Participation

Participation in each week’s Discussion Board forum accounts for a large percentage of your final grade in this course.
Please review the Course Syllabus for a comprehensive overview of course deliverables and the value associated with each.
It is my expectation that each of you will substantially contribute to the course discussion forums and respond to the posts of at least three other learners.
A substantive post should be at least 200 words. Responses such as “great posts” or “I agree” do notmeet the active engagement expectation.
Please feel free to draw on personal examples as you develop your responses to the Discussion Questions but you do need to demonstrate your understanding of the materials.
I do expect outside sources as well as class materials to formulate your post.
APA format is not necessary for DQ responses, but I do expect a proper citation for references.
Please use peer-related journals found through the GCU library and/or class materials to formulate your answers. Do not try to “Google” DQ’s as I am looking for class materials and examples from the weekly materials.
I will not accept responses that are from Wikipedia, Business com, or other popular business websites. You will not receive credit for generic web searches – this does not demonstrate graduate-level research.
Stay away from the use of personal pronouns when writing.As a graduate student, you are expected to write based on research and gathering of facts. Demonstrating your understanding of the materials is what you will be graded on. You will be marked down for lack of evidence to support your ideas.

Plagiarism

Plagiarism is the act of claiming credit for another’s work, accomplishments, or ideas without appropriate acknowledgment of the source of the information by including in-text citations and references.
This course requires the utilization of APA format for all course deliverables as noted in the course syllabus.
Whether this happens deliberately or inadvertently, whenever plagiarism has occurred, you have committed a Code of Conduct violation.
Please review your LopesWrite report prior to final submission.
Every act of plagiarism, no matter the severity, must be reported to the GCU administration (this includes your DQ’s, posts to your peers, and your papers).

Plagiarism includes:

Representing the ideas, expressions, or materials of another without due credit.
Paraphrasing or condensing ideas from another person’s work without proper citation and referencing.
Failing to document direct quotations without proper citation and referencing.
Depending upon the amount, severity, and frequency of the plagiarism that is committed, students may receive in-class penalties that range from coaching (for a minor omission), -20% grade penalties for resubmission, or zero credit for a specific assignment. University-level penalties may also occur, including suspension or even expulsion from the University.
If you are at all uncertain about what constitutes plagiarism, you should review the resources available in the Student Success Center. Also, please review the University’s policies about plagiarism which are covered in more detail in the GCU Catalog and the Student Handbook.
We will be utilizing the GCU APA Style Guide 7th edition located in the Student Success Center > The Writing Center for all course deliverables.

LopesWrite

All course assignments must be uploaded to the specific Module Assignment Drop Box, and also submitted to LopesWrite every week.
Please ensure that your assignment is uploaded to both locations under the Assignments DropBox. Detailed instructions for using LopesWrite are located in the Student Success Center.

Assignment Submissions

Please note that Microsoft Office is the software requirement at GCU.
I can open Word files or any file that is saved with a .rtf (Rich Text Format) extension. I am unable to open .wps files.
If you are using a “.wps” word processor, please save your files using the .rtf extension that is available from the drop-down box before uploading your files to the Assignment Drop Box.

Grade of Incomplete

The final grade of Incomplete is granted at the discretion of the instructor; however, students must meet certain specific criteria before this grade accommodation is even possible to consider.
The grade of Incomplete is reserved for times when students experience a serious extenuating circumstance or a crisis during the last week of class which prevents the completion of course requirements before the close of the grading period. Students also must pass the course at the time the request is made.
Please contact me personally if you are having difficulties in meeting course requirements or class deadlines during our time together. In addition, if you are experiencing personal challenges or difficulties, it is best to contact the Academic Counselor so that you can discuss the options that might be available to you, as well as each option’s academic and financial repercussions.

Grade Disputes

If you have any questions about a grade you have earned on an individual assignment or activity, please get in touch with mepersonally for further clarification.
While I have made every attempt to grade you fairly, on occasion a misunderstanding may occur, so please allow me the opportunity to learn your perspective if you believe this has occurred. Together, we should be able to resolve grading issues on individual assignments.
However, after we have discussed individual assignments’ point scores, if you still believe that the final grade you have earned at the end of the course is not commensurate with the quality of work you produced for this class, there is a formal Grade Grievance procedurewhich is outlined in the GCU Catalog and Student Handbook.