A local field potential (LFP) is an electrophysiological signal generated by the summed electric current flowing from multiple nearby neurons within a small volume of nervous tissue. Voltage is produced across the local extracellular space by action potentials and graded potentials in neurons in the area, and varies as a result of synaptic activity. "Potential" refers to electrical potential, or voltage, and particularly to voltage recorded with a microelectrode embedded within neuronal tissue, typically in the brain of an anesthetized animal or within a thin slice of brain tissue maintained in vitro.