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Am I incorrect in thinking that Vi remains at -70 mV (relative to ground)? Is Vi also changed by the addition of the battery, such that now Vi = (-70 + 1500) mV = 1430 mV? If that's the case then Vm = (1430 - 1500) mV = -70 mV. This would mean that the battery doesn't change Vm. Is that right? Thanks.

Embarrassed how rusty I am at this... Let's see what I can do. In the first situation, Vo = 0 mV, Vm = -70 mV. So Vi = Vm+Vo = -70 mV. In the second situation, the voltage difference between Vi and ground remains the same (Vi=-70 mV). Vo has been changed by the battery, so Vo = 1.5 V. The new membra...

Hello, I'm a grad student trying to model the effects of spatially-distributed, time-varying charges on an action potential. To do this, I'm simulating the Mainen and Sejnowski layer V pyramidal neuron ( http://senselab.med.yale.edu/modeldb/showmodel.asp?model=2488 ) and changing the conductance in ...

I made a toy model and confirmed that the stimulus is being read correctly. Both print statements and the List of stimulus vectors show the stimulus data. A print statement inside advance such as this: proc advance() { access SectionName print e_extracellular(.5) fadvance() } shows that only the las...

Hi Ted. As always, thanks for your thoughtful reply. I'm coming back to this problem after a few months away. Briefly, I'm reading in data from an external file and playing it to e_extracellular in each segment. My problem is that while the whole file is being read, only the last line is being used ...

Thanks again for the help. I'm encountering this problem. I'm using Matlab to generate extracellular potential traces as a function of xyz location and time. The extracellular potential for the center of each segment is then saved in a text file, and the data from this text file is then read with Ve...

ted wrote:At the oc> prompt, type this
NtimeSteps-359
then press the "Enter" key.
What do you see?

-5.6843419e-14

Ah, I see. And Vector.resize(n) floors n, right? If so, is it generally a good technique to use n+0.5 when resizing?

I'm encountering the following problem when using a variable to resize a vector. Briefly I use scanvar() to read in a value, then use this to calculate NtimeSteps. As you can see, NtimeSteps is initially 359, but tmpvec.resize(NtimeSteps) results in a vector with 358 elements. When I set NtimeSteps ...

Say I want to store e_extracellular(0.5) for each section at each time point in another variable for later analysis, how would I do this? I'm confused how to access and store variables (range or otherwise) as the simulation runs. As always, many thanks.

ted wrote: Have you verified that they play their values into the corresponding instances of e_extracellular in the course of a simulation?

What are the general ways to do this? If I'm playing a vector to e_extracellular, how would I access e_extracellular(t) for each section and each time point?

Beyond conceptual clarity, is there a motivation to split hoc code into multiple hoc files? For example, could all the hoc files found in the example here (http://www.neuron.yale.edu/phpBB/viewto ... f=28&t=168) be combined without affecting the implementation of the model?

I have a question about the Extracellular Stimulation and Recording post in the Hot Tips forum (https://www.neuron.yale.edu/phpBB/viewtopic.php?f=28&t=168). The post says that there are two approaches to extracellular stimulation. One is to introduce into the cable equation a current term that's...

Thanks so much. NEURON is a fantastic tool, and a big part of that is how helpful (and patient) this forum is. Thanks again. I'll let you know how it goes.

Back to your original question: all you have to do to simulate the effect of an extracellular field on a NEURON model is to insert the extracellular mechanism into the model's sections, then drive each segment's e_extracellular with a signal that corresponds to the time course of extracellular pote...

In your example, is Vm=0 precisely because there's no current flowing across the membrane? So there's no voltage drop because V=IR=0 - is that right?

Thanks a lot. The approach in the link looks very explicit. I'm working on that now.