profiles of LFPcal derived from CSD profiles using Equation 1 (methods). Note that our simultaneous recording from single arrays orthogonal to cortical layers cannot resolve the fine details of spatial distributions for sinks/sources. For example, lateral spread of activity may differ between layers, but cannot be elucidated by our methods. Regardless, application of Eq. 1 to CSD worked qualitatively well to calculate LFP when that was generated locally. LFPcal at low frequencies had largely similar profiles to LFPobs from the onset to the later inversions of polarity across similar subsets of the recording depths. As the tone frequency increased, the response became weaker. At high stimulus frequencies where CSD responses were negligible, the LFPcal diverged markedly from the LFPobs and more portions of signals differed in their sign (Fig. 4A fourth column).
