Offline orbitofrontal cortex reactivation depends on recency of place-reward changes and coheres with hippocampal replay.

The orbitofrontal cortex, one of the key neocortical areas in valuation and emotion, is critical for cognitive flexibility but its role in the consolidation of recently acquired information remains unclear. Here, we demonstrate orbitofrontal offline replay in the context of a place-reward association task on a maze with varying goal locations. When switches in place-reward coupling were applied, replay was enhanced relative to sessions with stable contingencies. Moreover, replay strength was positively correlated with the subsequent overnight change in behavioral performance. Interrogating relationships between orbitofrontal and hippocampal activity, we found that orbitofrontal and hippocampal replay could occur independently but became coordinated during a type of cortical state with strong spiking activity. These findings reveal a structured form of offline orbitofrontal ensemble activity that is correlated with cognitive flexibility required to adapt to changing task contingencies, and becomes associated with hippocampal replay only during a specific state of high cortical excitability.

SpecSeg is a versatile toolbox that segments neurons and neurites in chronic calcium imaging datasets based on low-frequency cross-spectral power.

Imaging calcium signals in neurons of animals using single- or multi-photon microscopy facilitates the study of coding in large neural populations. Such experiments produce massive datasets requiring powerful methods to extract responses from hundreds of neurons. We present SpecSeg, an open-source toolbox for (1) segmentation of regions of interest (ROIs) representing neuronal structures, (2) inspection and manual editing of ROIs, (3) neuropil correction and signal extraction, and (4) matching of ROIs in sequential recordings. ROI segmentation in SpecSeg is based on temporal cross-correlations of low-frequency components derived by Fourier analysis of each pixel with its neighbors. The approach is user-friendly, intuitive, and insightful and enables ROI detection around neurons or neurites. It works for single- (miniscope) and multi-photon microscopy data, eliminating the need for separate toolboxes. SpecSeg thus provides an efficient and versatile approach for analyzing calcium responses in neuronal structures imaged over prolonged periods of time.