Determination of Cortical Circuit Function Using Current Source-Density Analysis In Vivo

The recording of local field potentials (LFPs) has become a major tool in the analysis of electrical signaling in the brain. By yielding information about correlated activity in small neuronal populations, LFPs have been used to study mechanisms of sensory encoding, motor planning, cognitive function, and the occurrence of pathological activity patterns seen in epilepsy. However, the relatively poor spatial resolution of LFP signals often impedes characterization of the cellular processes underlying their generation. Thus, current source-density (CSD) analysis has been developed as a means to enhance the discrimination of extracellular current sinks and sources that are produced by neural synaptic activity. CSD analysis has been used by a number of groups to construct functional maps of the flow of information through cortical networks in vivo. Moreover, the relative technical ease of acquiring data for CSD computation has made this an attractive approach for neuroscientists in a diverse array of fields. Here, we describe the basic theory underlying CSD analysis and give a methodological overview of its application in the rodent neocortex.