The idea that LFP responses to tones octaves away from the BF at a penetration site in A1 is due to volume conduction, predicts that the CSD index derived by numeric differentiation from such an LFP profile should not contain the “volume conducted” components. In other words, the local spatiotemporal distribution of sources and sinks outlined by CSD analysis would not be able to generate the observed profile of LFP response (LFPobs). To test this idea, laminar LFP responses (LFPcal) were calculated back from CSD profiles. According to Poisson's differential equation, the local LFP profile is the spatial integration of its solution given a particular spatial distribution of current sinks/sources identified by CSD analysis (methods).
