Modelling and analysis of local field potentials for studying the function of cortical circuits

Key Points The past decade has witnessed a renewed interest in cortical local field potentials (LFPs) — that is, extracellularly recorded potentials with frequencies of up to about 500 Hz. Key reasons for this resurgence are that LFPs offer a unique window into key integrative synaptic processes and their potential use in neural prosthetics. Multiple neural signal processes contribute to the LFP, and computational methods are needed to tease apart these contributions and to properly interpret the signal in terms of its underlying neural activity. The biophysical origin of LFPs is well understood, and accurate LFP modelling schemes based on detailed neuron models have been established. Computational models explain how LFPs generated by cortical neural populations depend on electrode position, the dendritic morphologies of synaptically activated neurons, and on the spatial distribution and temporal correlations of synaptic inputs. New methods for current source density (CSD) analysis are better able to identify the three-dimensional position of neural sources. Advanced spectral and information-theoretical methods allow separation of independent contributions to the LFP in time and frequency. Spike–field relationships probe additional aspects of functional connectivity. Fitting the predictions of biophysical models to extracellular potentials allows the estimation of key network parameters. Simultaneous measurements of LFPs and other large-scale measures of neural activity (for example, functional MRI) can progress our understanding of how macroscopic and microscopic networks interact. Local field potentials (LFPs) provide a wealth of information about synaptic processing in cortical populations but are difficult to interpret. Einevoll and colleagues consider the neural origin of cortical LFPs and discuss LFP modelling and analysis methods that can improve the interpretation of LFP data. The past decade has witnessed a renewed interest in cortical local field potentials (LFPs) — that is, extracellularly recorded potentials with frequencies of up to ∼500 Hz. This is due to both the advent of multielectrodes, which has enabled recording of LFPs at tens to hundreds of sites simultaneously, and the insight that LFPs offer a unique window into key integrative synaptic processes in cortical populations. However, owing to its numerous potential neural sources, the LFP is more difficult to interpret than are spikes. Careful mathematical modelling and analysis are nee