Lab 3: Hodgkin Huxley Neurons
- run lab3.py, a Hodgkin Huxley neuron(
lab3.py or lab3py.txt).
- 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).
- Now set the e_rev_leak in makeNeurons by the step 3 comment.
Notice the different behaviour of the neurons, in particular
- 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?
- If you change v_offset of cells 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
- 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.
- 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.
- Explore different parameter settings and input values.