Can anyone explain me if there is a difference in amplitude of signals between extracellular recording and intracellular recording. I know that the amplitude of neural signals when an action potential occurs is from -70mV to 45mV for intracellular recording. The same results are for extracellular recording?Can someone help me?
Also, I have read a paper that refers:
Neural signals from extracellular recording are very weak (typically between 10 μV and 500 μV). As a result, amplification is needed before such signals can be processed further."
So my question is why neural signals are so weak (maybe author when he says 10μV refers to amplitude) when we know that an action potential has amplitude approximately 75mV(-70mV to 45mV)?