Virtual Neurons 2.0 Gabe Al-Ghalith Janet M Dubinsky 7/31/12 • Everyone turn on your computers and get web access via UMN guest. • Hook up 1 computer at the table to your table monitor. Turn both monitor and computer on. • Go to http://brainu.org/virtual-neuronssneak-peek • Click “click here” • Click start • Check Show Graph & Action Potential Meters. • Click Continue As an individual, work through 1-5, then as a group do 6: 5 min 1. What do you see? 2. What does it remind you of? 3. How does it make you feel? 4. What questions does it raise? 5. Speculate on what you think you should do next. 6. Plan a course of action as a group. As a group, make the following circuits, 5 min. 1. 2. 3. 4. 5. Make the muscle twitch using 2 neurons. How fast is it twitching? What are the ticks on the graph? What are the lines on the graph? Explain the relationships between the firing rates of the different neurons and the muscle twitching rate. 6. Write an equation for # of muscle twitches, m, as a function of time, t. How to manipulate pieces and buttons and read graph. m = (t-2)/2 = t/2 - 1 m t Idea: Use PrintScreen to capture a circuit and paste it in a doc or ppt notebook. Make these changes to your circuit, 5 min. 1. The Action Potential Threshold meters are on the left panel. 2. Click on the threshold meter for your motor neuron. 3. What happened to the muscle twitch rate? 4. If you click on the meter again, what do you predict will happen to muscle twitching? 5. What is meter #7 for? 6. What will happen if you click on the meter for your sensory neuron? Try it. How to change thresholds As an individual or as a group, make the following circuits: 5 min 1. Make the muscle twitch using 3 neurons with all threshold meters set to 2. 2. How fast is the muscle twitching now? 3. Why? How does this compare with your previous 2 neuron circuit? 4. What happens if you use interneuron 7 instead of interneuron 3 or 4? 5. What happens when you change thresholds in this circuit. 6. Make the muscle twitch using both interneurons 3 and 4. 7. Explain how this last circuit works using the information from the graph. Interneurons: Excitatory & Inhibitory As an individual, make the following circuits 5 min 1. Start with 3 neuron circuit. 2. Click Settings; check Advanced Neuron Shapes; click Continue 3. Click Change , Click the sensory neuron cell body & choose 3rd shape from bottom. 4. Adjust positions & length of interneuron using Change button, if necessary. 5. What’s muscle twitch rate now? How does this compare to previous 2 circuits? 6. Describe the effect of the extra process. Use data & observations to support your claims. 7. Why is this called Feed Forward? Shape changes & Feed forward As an individual, make the following circuits 5 min 1. Start with simple 3 neuron circuit 2. Change the shape of the motorneuron to be branched. 3. Use the Add & Change buttons to build a Feedback Loop onto the interneuron or motorneuron dendrites. 4. What does this feedback do to the rate of muscle firing? Why? 5. What happens when you play with thresholds in this circuit? Positive Feedback What did I change in this circuit at 30 sec? In pairs, use 1 computer to change the positive feedback circuit: 5’ 1. Start with the same positive feedback circuit on both computers. 2. On one computer, make the interneuron feeding back onto the main circuit Neuron 7. What do you predict will happen? 3. Use the graph to explain the differences in firing rates between the two circuits. 4. Why is this called negative feedback? 5. What are some other instances in your life when you’ve encountered + and – feedback? 6. Why do neuronal circuits need feedback? Negative feedback & Homeostasis At your table, make all of the following circuits. Save PrintScreen shots as proof you made the circuits. First table to complete all circuits wins! • Make the muscle twitch in a syncopated rhythm! • Make a circuit that begins with a spontaneously firing interneuron. • Make a circuit that uses 2 sensory neurons to control the muscle firing. • Use a spontaneously firing inhibitory interneuron to control a circuit. • Build a circuit that includes inhibiting the spontaneously firing inhibitory interneuron. Homeostasis Input Set Point Comparator Difference Control Center Change Signal Output Effector Internal Measure of Output Make a circuit of this Homeostatic System. Internal Measure of Output Output Comparator Σ Difference Effector Control Control Center Center Set Point Internal Measure of Output Output Σ Difference Effector Set Points Control Center How would you use this lesson in your classroom? This is alpha version. What should we change in the beta version?