Prefrontal cortical activity predicts the occurrence of nonlocal hippocampal representations during spatial navigation

The receptive field of a neuron describes the regions of a stimulus space where the neuron is consistently active. Sparse spiking outside of the receptive field is often considered to be noise, rather than a reflection of information processing. Whether this characterization is accurate remains unclear. We therefore contrasted the sparse, temporally isolated spiking of hippocampal CA1 place cells to the consistent, temporally adjacent spiking seen within their spatial receptive fields (place fields). We found that isolated spikes, which occur during locomotion, are strongly phase coupled to hippocampal theta oscillations and transiently express coherent nonlocal spatial representations. Further, prefrontal cortical activity is coordinated with and can predict the occurrence of future isolated spiking events. Rather than local noise within the hippocampus, sparse, isolated place cell spiking reflects a coordinated cortical-hippocampal process consistent with the generation of nonlocal scenario representations during active navigation.

Automated summary

In this study, the researchers compared the spiking activity of place cells in the hippocampal CA1 region in different situations, finding that isolated spikes are strongly phase coupled to hippocampal theta oscillations and express coherent nonlocal spatial representations. This type of spiking activity is not considered local noise, but rather reflects a coordinated cortical-hippocampal process.