Uncovering the mysterious origins of local field potentials.

In this issue of Neuron, Katzner et al. use a combination of multielectrode recordings and optical imaging to determine the spatial extent of local field potential (LFP) activity in primary visual cortex. By estimating the orientation selectivity of stimulus-evoked LFP activity from the map of orientation preference obtained using optical imaging, they find that LFP selectivity is best fit using signals within 250 microm of the recording electrode.