[Neuroscience] Explaination of the direction of field potentials

[Bill]

Hi,

This may seem like a very simply question, but I've heard two different
electrophysiologists (both of whom publish in fancy journals as a
matter of course) give two different explanations as to why field
potentials of action potentials recorded from a cell body region (e.g.
Stratum Pyramidale of CA1) are positive, while field potentials caused
by dendritic excitation (e.g. Stratum Radiatum of CA1) are negative.

What is your understanding of this?

Thanks,