 In some areas of the brain, such as the hippocampus, neurons are arranged in such a way that they all receive synaptic inputs in the same area.Because these neurons are in the same orientation, the extracellular signals from the generation of action potentials don't cancel out, but rather add up to give a signal that can easily be recorded with a field electrode.The PS is usually recorded with an extracellular electrode placed close to neural cell bodies or axons.