In contrast, inhibitory input to the soma (for example, from a GABAergic basket cell) produces an active source in the soma and a pasive sink in the dendrites.
An action potential arising near the soma causes the following dipole:
Extracellular signals are not stationary in time or space, and since many neurons are active at the same time, extracellular potentials become complex.
Solid Angle
From an observation point in a volume conductor, the measured potential (with respect to a distant reference) will depend on the solid angle made with the dipole. The solid angle depends on the physical size of the dipole and the distance between the observation point and the dipole.
If there are many dipoles, superposition allows that the measured potential at the observation point represents the linear sum of that contributed by each dipole individually.
Continue... Dendritic Fields