The lab represents different outputs produced on a neuron when an electric pulse of 2V is given; it produces an output of action potential in few volts. The lab also shows the waveforms of sodium and potassium ions. Actually in a real neuron, the action potential will be in tens of milliseconds. But for a better analytical study we made the voltage in volts. When the input is varied we can see considerable changes in the size of action potential.
1. Lab Experiment Overall Goals:
The goal of this lab exercise is to generate action potential of a neuron. The remote trigger equipment will control the stimuli and resistance operating on the cell. By varying these parameters, the action potential will be produced. By controlling one switch we can also study about Na and k ions.
This remote trigger experiment performs experiments on an analog neuron. The experimental setup is housed at Amrita University, Amritapuri Campus and has the following features:
- Neuron model uses a power supply, function generator, transistors, resistors and capacitor.
- Interface consists of external step signal input and one switch to enable and disable sodium & potassium currents.
- The action potential, sodium and potassium created by the analog neuron is plotted using standard Data Acquisition Equipment interfaced to a computer.
- Output is collected, stored and displayed.
Here membrane potential along with passive membrane effects are plotted. In the interface window we can see four graphs, one that disable Na button, one that disable K button, four radio buttons along with one submit button and one reset button.
When you give an input pulse, you can see the stimuli on the first graph (on input excitation graph) on the interface window as below,
- Set the input stimuli by selecting the radio button of particular value.
- Click to apply the stimuli.Verify through the live video window whether the GREEN light is
blinking or not.
- Frequency, resting potential offset and pulse width of the input step signal are assigned for every input.
- View the membrane potential, Sodium current and Potassium current. (The output will be is similar to the below figure).
- Click to understand the effects of sodium ions on membrane potential.
- Click to understand the effects of potassium ions on membrane potential.
- User can analyze the values at every point of signals by pointing the mouse over each signal.
- Click to reset the experiment.
- The PCB & circuit diagram can be viewed from the panel To switch between circuit diagram & PCB use button.
10. The live video can be viewed from panel.
For example start the experiments by connecting the device. Select the input stimuli with A=1Vpp and F=20Hz. Apply the input excitation to the analog neuron circuit by clicking start button. Maximize the live video window to verify whether device is running or not. The applied input stimuli, generated action potential, Sodium current and potassium current can be viewed in the input stimuli,membrane potential, Sodium current and potassium current graph respectively. To find out the effects of ion channel disable ion channel one by one . Repeat the same procedure for other input stimuli. The user can also export the values which are chosen to get plotted on the graph using the Export Button. After clicking on this button, you can save your file at the specified location in .csv format and can use later by importing these values into either MS-Excel sheet or MATLAB for high resolution images.