Imaging local field potentials in the rat barrel cortex

Local field potentials (LFPs) contain relevant information about neuronal population activity [1]. They are commonly measured in the brain to investigate information processing by neural circuits and for neuroprosthetics applications. We present a novel method allowing for in vivo `electrical imaging' of LFPs. An oxide-insulated neural probe was implanted in the brain of a rat, establishing a capacitive electrical coupling with the nervous tissue. Thanks to a multiplexed array of 256 capacitive micro electrodes, the probe could record two dimensional LFP profiles with unprecedented spatial resolution, down to fifteen micrometers. A recording example within a single-barrel of the somatosensory cortex of an anaesthetized rat is provided.