Broad band neuroelectric field potentials recorded from within the brain have been used to investigate brain functioning in nonhuman animals began shortly after the discovery of the electroencephalogram or EEG (Bullock, 1945;Galambos, 1941;Marshall et al., 1937). While the technique was overshadowed by action potential recording for a number of years, its importance has re-emerged over the past decade because of the observations that the field potential is linked to the neural underpinnings of hemodynamic signals (Logothetis et al., 2001), as well as magnetoencephalographic (MEG) and scalp EEG signals (Heitz et al., 2010;Mitzdorf, 1985;Schroeder et al., 1991; Steinschneider et al., 1992). Additionally, it is now widely recognized [e.g., (Schroeder et al., 1998)] that because field potentials are generated by transmembrane current flow in ensembles of neurons (Eccles, 1951; Lorente de No, 1947), they can index processes and events that are causal to action potentials. Finally, field potentials form part of the signal spectrum that can drive neuro-prosthetic devices (Hatsopoulos and Donoghue, 2009), even when accessed indirectly with noninvasive recording from the scalp (Wolpaw, 2007).
