Spatiotemporal patterns of current source density in the prefrontal cortex of a behaving monkey

One of the fundamental missions of neuroscience is to explore the input and output properties of neuronal networks to reveal their functional significance. However, it is technically difficult to examine synaptic inputs into neuronal circuits in behaving animals. Here, we conducted current source density (CSD) analysis on local field potentials (LFPs) recorded simultaneously using a multi-contact electrode in the prefrontal cortex (PFC) of a behaving monkey. We observed current sink task-dependent spatiotemporal patterns considered to reflect the synaptic input to neurons adjacent to the recording site. Specifically, the inferior convex current sink in the PFC was dominant during the delay period, whereas the current sink was prominent in the principal sulcus during the sample cue and test cue periods. Surprisingly, sulcus current sink patterns were spatially periodic, which corresponds to the columnar structure suggested by previous anatomical studies. The approaches used in the current study will help to elucidate how the PFC network performs executive functions according to its synaptic input.