Membrane capacitance estimation
Posted: Wed Jul 05, 2023 6:21 pm
Hi everyone!
I have 8 months experience with NEURON and some question are starting to arise in my mind.
In particular, I am trying to calculate the membrane capacitance Cm of a multi-compartment conductance-based neuron model.
I calculate the membrane capacitance developing a voltage clamp protocol in the soma: from -70 mV to -80 mV. Then I calculate the charge Q integrating the area under the curve of the capacitive current. Once found the charge Q, I obtain Cm from the equation Cm*Vm= Q
Now, I am asking myself if it really the TOTAL membrane capacitance of the cell, or if it is something that should be called differently...
The value that I obtain as Cm from the protocol make me think that what I obtain is a membrane capacitance that is valid for the confined region (soma) that I am studying and its neighbouring regions.
Let's say that my specific membrane capacitance is 1 uF/cm^2 in all the sections of my model. If my neuron has great dimension (for instance a long axon), do you think that distal regions really impact on the experimental calculations (or the one that I've cited before with voltage clamp)?
These doubts arose because I believed that the total membrane capacitance could be described as:
Cm = cm*A(soma) + cm*A(dendrites) + cm*A(axon) + ...
where cm is the specific membrane capacitance of each section and A is the area of the section.
Any advice?
I have 8 months experience with NEURON and some question are starting to arise in my mind.
In particular, I am trying to calculate the membrane capacitance Cm of a multi-compartment conductance-based neuron model.
I calculate the membrane capacitance developing a voltage clamp protocol in the soma: from -70 mV to -80 mV. Then I calculate the charge Q integrating the area under the curve of the capacitive current. Once found the charge Q, I obtain Cm from the equation Cm*Vm= Q
Now, I am asking myself if it really the TOTAL membrane capacitance of the cell, or if it is something that should be called differently...
The value that I obtain as Cm from the protocol make me think that what I obtain is a membrane capacitance that is valid for the confined region (soma) that I am studying and its neighbouring regions.
Let's say that my specific membrane capacitance is 1 uF/cm^2 in all the sections of my model. If my neuron has great dimension (for instance a long axon), do you think that distal regions really impact on the experimental calculations (or the one that I've cited before with voltage clamp)?
These doubts arose because I believed that the total membrane capacitance could be described as:
Cm = cm*A(soma) + cm*A(dendrites) + cm*A(axon) + ...
where cm is the specific membrane capacitance of each section and A is the area of the section.
Any advice?