Problems using VClamp

When Python is the interpreter, what is a good
design for the interface to the basic NEURON
concepts.

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camilhamdane
Posts: 8
Joined: Mon Aug 05, 2019 7:37 am

Problems using VClamp

Post by camilhamdane » Mon Oct 21, 2019 4:40 am

Hello everyone,

I have been dealing with a specific problem for the past weeks, and I cannot wrap my head around it. Basically, I have a cell with multiple sections where I want to inject a specific voltage in mV, coming from a cell in NEST. Since I cannot form any synapses between them, I thought about artificially stimulating the NEURON cells with the exact value that should be sent by the NEST cells.

For this matter, I chose to work with VClamps, and this is the code that I got for the stimulation:

Code: Select all

stim = h.VClamp(soma(0.5))

def stimulate():
	stim.amp[0] = 0
	stim.dur[0] = 5
	stim.amp[1] = 40
	stim.dur[1] = 0.1
	stim.amp[2] = self.stim.dur[2] = 0
	
soma_v_vec = h.Vector()
t_vec = h.Vector()
soma_v_vec.record(soma(0.5)._ref_v)
t_vec.record(h._ref_t)

h.finitialize(-65)
stimulate()
h.tstop = 10
h.run()

pyplot.figure(figsize=(8,4))
soma_plot = pyplot.plot(t_vec, soma_v_vec)
pyplot.xlabel('time (ms)')
pyplot.ylabel('mV')
pyplot.show()
What I expected was first a "stimulation" of 0 mV for 5 ms, resulting in a flat signal at the rest potential, then the action potential at 5 ms, and a return to the rest potential, just as a normal neuron would do...
Instead this is what I get:
Image

Apparently, VClamps only "set" the signal to the specified voltage instead of injecting it to the already existing voltage.

Am I doing it right ? Am I missing something ? Is it a matter of parameters inside the soma ? Currently I have a hh module, with standard values, is that what's causing the issue here ?

Thank you so much,
Camil

ted
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Re: Problems using VClamp

Post by ted » Mon Oct 21, 2019 9:43 am

I have a cell with multiple sections where I want to inject a specific voltage in mV, coming from a cell in NEST. Since I cannot form any synapses between them, I thought about artificially stimulating the NEURON cells with the exact value that should be sent by the NEST cells.

For this matter, I chose to work with VClamps
You want the NEST cell to be presynaptic to the NEURON cell? If so, voltage clamps aren't going to do anything useful for you. Presumably you want a spike in the presynaptic cell to activate a synapse attached to the postsynaptic cell--did I guess correctly?

Next question: do you want the cells in your NEURON model to communicate back to the cells in the NEST model during the same simulation?

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