Somatic current injection

[udi]

I want to simulate the affect of somtic current injection in order to hyperpolarize the cell resting potetial. When I do it in the lab I inject negative DC current to the soma during the experiment. When using NEURON, is it sufficient to change Vm (e.g -80 instead of -65) instead of negative current injection?

Thanks in advance!

[ted]

The default initialization in NEURON is a "global voltage clamp" initialization.
That is, it sets the membrane potential throughout the entire model to v_init
(whose numeric value appears next to the Init button), and forces all voltage-
dependent variables to their steady state values for that membrane potential.

When you inject hyperpolarizing current into a cell in the lab, membrane
potential does not fall to the same level throughout the cell (unless the cell
is very small). Also, the current pulse may not be long enough for very
slow mechanisms to reach their steady states (e.g. some K channels),

So in general, the answer to your question is no, initializing to a particular
membrane potential does not have the same effect as injecting a polarizing
current. But if your cells and your model are very small, and the current you
inject lasts so long that all mechanisms can reach their steady state, the results
will be the same.