Hippocampal replay of experience at real-world speeds

Representations related to past experiences play a critical role in memory and decision-making processes. The rat hippocampus expresses these types of representations during sharp-wave ripple (SWR) events, and previous work identified a minority of SWRs that contain “replay” of spatial trajectories at ~20x the movement speed of the animal. Efforts to understand replay typically make multiple assumptions about which events to examine and what sorts of representations constitute replay. We therefore lack a clear understanding of both the prevalence and the range of representational dynamics associated with replay. Here we develop a state space model that uses a combination of movement dynamics of different speeds to capture the spatial content and time evolution of replay during SWRs. Using this model, we find that the large majority of replay events contain spatially coherent, interpretable content. Furthermore, many events progress at real-world, rather than accelerated, movement speeds, consistent with actual experiences.

Methods
# Dataset description

This dataset contains extracellular neural recordings of ten male Long Evans rats (500-700 g, 4-9 months old) that were trained on a W-track spatial alternation task. 9 rats contributed to previous studies (Karlsson et al. 2008, 2009, Carr et al. 2012, Kay et al. 2016, 2020). Neural activity was recorded using tetrodes in CA1, CA2, CA3, MEC, Subiculum, and Dentate Gyrus depending on the rat.

This dataset has been processed to extract the LFP, sharp wave ripple times, clustered cells, multiunit spikes and associated spike features, and position of the animal using custom Frank lab Matlab code.

### Rats

1. Coriander

2. Bond

3. Chapati

4. Conley

5. Dave

6. Dudley

7. Egypt

8. Frank

9. Government

10. Remy

The data were collected by Dr. Mattias Karlsson (animals Bond, Frank, Conley, Dudley), Dr. Margaret Carr (animal Coriander), Dr. Kenneth Kay (animals Chapati, Dave), Drs. Kenneth Kay and Marielena Sosa (animal Egypt), Drs. Kenneth Kay and Jason E. Chung (animal Government), and Dr. Anna K. Gillespie (animal Remy).

Data from Drs. Margaret Carr and Mattias Karlsson was previously posted at CRCNS: http://crcns.org/data-sets/hc/hc-6. Any publications made using that data should cite the data set using the following:

```

Mattias Karlsson, Margaret Carr, Loren M. Frank (2015). Simultaneous extracellular recordings from hippocampal areas CA1 and CA3 (or MEC and CA1) from rats performing an alternation task in two W-shaped tracks that are geometrically identically but visually distinct.

CRCNS.org. http://dx.doi.org/10.6080/K0NK3BZJ

```

This dataset is open to reuse with citation. Please contact Loren Frank ([e-mail]) with questions about the dataset.