Hi, Everybody:
I have a question from Johnston & Wu's textbook(Foundations of Cellular
Neurophysiology). It is about instantaneous current-voltage relation.
A figure shows that the neuron's steady-state current is -1 nA/um^2 at
both Vm=-80mV and -100mV; the neuron's instantaneous current is -0.2
nA/uM^2 at both Vm=-80mV and -100mV. Question: If the neuron is hold
Vh=-80mV for a long period of time and jump to Vc=-100mV, what is the
current trace look like?
The answer from the book(p46) is: the current is a flat line at -1
nA/um^2 (there is a flip at the time of voltage change due to capacitance).
My intended answer: the current was at -1 nA/um^2 before the voltage
change. When voltage changes, the current jump to -0.2 nA/um^2, then
relaxes with certain time contant to -1 nA/um^2 steady-state current.
I think when author or anybody mentions instantaneous current, he should
mention what the prepulse voltage is. Here, the author doesn't say it.
Thank you very much. I greatly appreciate your help.
Best Regards,
Xiaoshen