Techniques

When an EPSP is generated in the dendrites of a neuron an extracellular electrode detects a negative voltage difference, resulting from Na+ currents flowing inside the neuron’s cytoplasm. The current completes a loop further away the excitatory input (Na+ flows outside the cell), being recorded as a positive voltage difference by an extracellular electrode. This process can last hundreds of milliseconds. Thus, a small dipole is generated!!

EEG