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Lab 3: Hodgkin Huxley Neurons

  1. run lab3.py, a Hodgkin Huxley neuron( lab3.py or lab3py.txt).
  2. comment out all of the print statements. Note that the recordable bits are variables and the default values are for constants (which you can set).
  3. Now set the e_rev_leak in makeNeurons by the step 3 comment. Notice the different behaviour of the neurons, in particular the spikes.
  4. Now comment out the useDCSource in main. Note how neuron 1 actually spikes with no input. Why? That's a spontaneous spike. Will it do it again. How can you check?
  5. If you change v_offset of cells[1] to greater than -60, it won't spike. Why? What do the parameters mean? The note on HH neurons in the PyNN docs is "Single-compartment Hodgkin-Huxley-type neuron with transient sodium and delayed-rectifier potassium currents using the ion channel models from Traub." Traub is pretty famous and has a scad of papers. I couldn't find the one with these variables. Sodium Currents Activate without a Hodgkin and Huxley-Type Delay in Central Mammalian Neurons seems close, but not quite right. Can anyone find it.
  6. v_reset seems like the firing threshold from LIF models. In HH terms that's when the voltage is large enough to open the sodium channels. e_rev_Na seems like it should be when the sodium gate is shut. Let's try to raise it. Comment out the v_offset change (so it fires) and uncomment the e_rev_Na change.
  7. When does the potassium gate come on? When does it close? e_rev_E doesn't seem to open it. Let's try two similar neurons with just that difference. That doesn't seem to do it. Perhaps the model just uses e_rev_Na for opening the potassium gate too. It seems from other models that e_rev_E is from a more general model. The g_bars are in a different unit (seiverts not volts) so those seem wrong.
  8. Explore different parameter settings and input values.