Hi all,(adsbygoogle = window.adsbygoogle || []).push({});

I'm trying to understand the electrical model of a neuron, and I have 2 questions.

I'm a little confused about the time constant in this electrical model of neuron recording:

The time constant shown is tau = C*(Rm*Rs)/(Rm+Rs), which implies that the resistors are in parallel. However, to me, it looks like the resistors are in series. I feel like I'm missing something here.

First question: Why is the time constant C*(Rm*Rs)/(Rm+Rs) rather than C*(Rm+Rs)?

To make matters worse, earlier in the lecture this circuit was shown, implying the resistor represented membrane resistance: (ignore the values)

There is a current source here.

In the first picture, the diagram is using a voltage source. The second diagram is the same thing as a series RC circuit with a voltage source, just using a source transformation (I think). I looked up parallel RC circuits (with a voltage source) and found they had very different properties than series RC circuits. Note: The first picture seems to show a voltage clamp, while the second was just a general model. Might or might not change things.

Second Question: How can I reconcile these two diagrams?

What's a correct neuron model?

Thanks.

Edit: Some of the information I was given could be erroneous; i.e. I don't trust the lecture slides.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Neuron Electrical Model, time constant

**Physics Forums | Science Articles, Homework Help, Discussion**