Lab 8 Checklist

Biological Sciences 300/301, Smith College | Neurophysiology

Checklist for Lab 8:
Discussion of the crayfish swimmeret system.

http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs/labcheck8.html

UPDATED: March 23, 2009

Background

Lab 8 is a prepared discussion of the crayfish swimmeret system. It includes a writing assignment that is due at the start of lab.

The online Web pages give background information about the swimmeret system and links to additional materials, including visual material on Crayfish Neuroanatomy and a tipsheet, Tips on Writing about Neuroscience. The online background material will help you understand the readings.

Readings

Cattaert, D and D LeRay (2001) Adaptive motor control in crayfish. Progress in Neurobiology 63: 199-240. (A one-page excerpt that briefly summarizes the swimmeret motor system).

Mulloney, B, D Murchison and A Chrachri (1993) Modular organization of pattern-generating circuits in a segmental motor system: the swimmerets of crayfish. Seminars in the Neurosciences 5: 49-57. (An excerpt giving a basic description of the swimmeret pattern generator).

Braun, G and B Mulloney (1993) Cholinergic modulation of the swimmeret motor system in crayfish. J. Neurophysiology 70 (6): 2391-8. (This is the paper to focus on.)

Mulloney, B (1997) A test of the excitability-gradient hypothesis in the swimmeret system of crayfish. J. Neuroscience 17(5):1860-8. (Fig. 2 only, presenting additional experiments with the cholinergic agonist carbachol.)

Acevedo, LD, WM Hall, and B Mulloney (1994) Proctolin and excitation of the crayfish swimmeret system. J Comp Neurol 345(4):612-27. (Abstract only. The paper describes neurons that contain proctolin and that probably activate the swimmeret CPG.)

Writing
Assignment

1. Write a three-to-four page paper that you bring with you to lab.
Describe the swimmeret system and discuss the potential sites of action of transmitters that modulate the system. As you read the papers, ask yourself what point each figure is making, and how its component parts contribute to that point. To organize the information about the different drugs and transmitters, try to imagine where on the model of the swimmeret CPG circuit (below) the drugs might act. (No one knows where they actually act.) Base your paper on relevant information from the five readings. It is useful to discuss the readings with your classmates, but you must write your paper by yourself.

There is no need to type out a bibliography for your paper, since all of us have the list of five references. Cite the papers using the author(s) and year in parentheses, as in (Cattaert and LeRay, 2001), (Mulloney et al., 1993), etc. Cite only the most important facts or ideas, not every detail.

2. In lab, after discussing the project with your lab partner(s), write a single paragraph that briefly describes an experiment on the swimmeret motor system that will be your group's lab project. Also include a list of drugs that you will need and their approximate concentrations. Put everyone's names on the page. The paragraph's purpose is to describe what you are thinking of doing as a first step in shaping a realistic project. It does not have to be the last word on the subject.

In planning your project, assume that you will employ extracellular electrodes and equipment that you have already used in lab. Use carbachol, proctolin, or another agonist to elicit the swimmeret motor pattern. It is not necessary to give experimental details beyond the overall plan of the experiment. Your experiments do not have to be new. For example, trying to record simultaneously from both sides of a ganglion or both branches of N1 can be an interesting challenge. If you are thinking of a pharmacological experiment, limit yourself to one drug. You can also use a drug (proctolin or carbachol) to initiate the rhythm while you investigate some other aspect (like the timing between ganglia). Keep your experiment simple. You'll want to be able to repeat experiments, and we have only a few weeks.

After the
Discussion

Try a practice dissection of an isolated nerve cord -- it's worth the time to do it today. See the video and instructions for Labs 9-12.

Diagram of a revised model of the local circuit in each swimmeret module that drives alternating bursts in swimmeret motor neurons.Three types of nonspiking local interneurons (1A, 1B, 2A) make graded, monosynaptic inhibitory connections (black filled circles) with motor neurons of particular types (PSE, PSI, RSE, RSI). The numbers in parentheses are the numbers of neurons of each type in one module. Additional coordinating, command, and sensory feedback connections are also shown.

Adapted from figure 10 of Mulloney, B (2003) During fictive locomotion, graded synaptic currents drive bursts of impulses in swimmeret motor neurons. J Neuroscience 23(13): 5953-5962.

	Biological Sciences 300/301, Smith College \| Neurophysiology Checklist for Lab 8: Discussion of the crayfish swimmeret system. http://www.science.smith.edu/departments/NeuroSci/courses/bio330/labs/labcheck8.html
	UPDATED: March 23, 2009
Background	Lab 8 is a prepared discussion of the crayfish swimmeret system. It includes a writing assignment that is due at the start of lab. The online Web pages give background information about the swimmeret system and links to additional materials, including visual material on Crayfish Neuroanatomy and a tipsheet, Tips on Writing about Neuroscience. The online background material will help you understand the readings.
Readings	Cattaert, D and D LeRay (2001) Adaptive motor control in crayfish. Progress in Neurobiology 63: 199-240. (A one-page excerpt that briefly summarizes the swimmeret motor system). Mulloney, B, D Murchison and A Chrachri (1993) Modular organization of pattern-generating circuits in a segmental motor system: the swimmerets of crayfish. Seminars in the Neurosciences 5: 49-57. (An excerpt giving a basic description of the swimmeret pattern generator). Braun, G and B Mulloney (1993) Cholinergic modulation of the swimmeret motor system in crayfish. J. Neurophysiology 70 (6): 2391-8. (This is the paper to focus on.) Mulloney, B (1997) A test of the excitability-gradient hypothesis in the swimmeret system of crayfish. J. Neuroscience 17(5):1860-8. (Fig. 2 only, presenting additional experiments with the cholinergic agonist carbachol.) Acevedo, LD, WM Hall, and B Mulloney (1994) Proctolin and excitation of the crayfish swimmeret system. J Comp Neurol 345(4):612-27. (Abstract only. The paper describes neurons that contain proctolin and that probably activate the swimmeret CPG.)
Writing Assignment	1. Write a three-to-four page paper that you bring with you to lab. Describe the swimmeret system and discuss the potential sites of action of transmitters that modulate the system. As you read the papers, ask yourself what point each figure is making, and how its component parts contribute to that point. To organize the information about the different drugs and transmitters, try to imagine where on the model of the swimmeret CPG circuit (below) the drugs might act. (No one knows where they actually act.) Base your paper on relevant information from the five readings. It is useful to discuss the readings with your classmates, but you must write your paper by yourself. There is no need to type out a bibliography for your paper, since all of us have the list of five references. Cite the papers using the author(s) and year in parentheses, as in (Cattaert and LeRay, 2001), (Mulloney et al., 1993), etc. Cite only the most important facts or ideas, not every detail. 2. In lab, after discussing the project with your lab partner(s), write a single paragraph that briefly describes an experiment on the swimmeret motor system that will be your group's lab project. Also include a list of drugs that you will need and their approximate concentrations. Put everyone's names on the page. The paragraph's purpose is to describe what you are thinking of doing as a first step in shaping a realistic project. It does not have to be the last word on the subject. In planning your project, assume that you will employ extracellular electrodes and equipment that you have already used in lab. Use carbachol, proctolin, or another agonist to elicit the swimmeret motor pattern. It is not necessary to give experimental details beyond the overall plan of the experiment. Your experiments do not have to be new. For example, trying to record simultaneously from both sides of a ganglion or both branches of N1 can be an interesting challenge. If you are thinking of a pharmacological experiment, limit yourself to one drug. You can also use a drug (proctolin or carbachol) to initiate the rhythm while you investigate some other aspect (like the timing between ganglia). Keep your experiment simple. You'll want to be able to repeat experiments, and we have only a few weeks.
After the Discussion	Try a practice dissection of an isolated nerve cord -- it's worth the time to do it today. See the video and instructions for Labs 9-12.

	Diagram of a revised model of the local circuit in each swimmeret module that drives alternating bursts in swimmeret motor neurons.Three types of nonspiking local interneurons (1A, 1B, 2A) make graded, monosynaptic inhibitory connections (black filled circles) with motor neurons of particular types (PSE, PSI, RSE, RSI). The numbers in parentheses are the numbers of neurons of each type in one module. Additional coordinating, command, and sensory feedback connections are also shown. Adapted from figure 10 of Mulloney, B (2003) During fictive locomotion, graded synaptic currents drive bursts of impulses in swimmeret motor neurons. J Neuroscience 23(13): 5953-5962.

Biological Sciences 300/301, Smith College | Neurophysiology

Checklist for Lab 8: Discussion of the crayfish swimmeret system.

Background

Readings

Writing Assignment

After the Discussion

Checklist for Lab 8:
Discussion of the crayfish swimmeret system.

Writing
Assignment

After the
Discussion