Spindle oscillations in communicating axons within a reconstituted hippocampal formation are strongest in CA3 without thalamus

Spindle-shaped waves of oscillations emerge in EEG scalp recordings during human and rodent non-REM sleep.  The association of these 10-16 Hz oscillations with events during prior wakefulness suggests a role in memory consolidation.  Human and rodent depth electrodes in the brain record strong spindles throughout the cortex and hippocampus, with possible origins in the thalamus.  However, the source and targets of the spindle oscillations from the hippocampus are unclear. Here, we employed an in vitro reconstruction of four subregions of the hippocampal formation with separate microfluidic tunnels for single axon communication between subregions assembled on top of a microelectrode array.  We recorded spontaneous 400-1000-ms-long spindle waves at 10-16 Hz in single axons passing between subregions, as well as from individual neurons in those subregions.  The highest amplitudes and most frequent occurrences suggest origins ..., Data was collected from the experiments of Vakilna (2021) using four PDMS compartments of primary neurons connected by microfluidic tunnels over a 120-electrode array (MEA) (Figure 1A).  Briefly, recordings were made using a Multichannel Systems MEA120 1100× amplifier (Multichannel Systems, Reutlingen, Germany). This study focused only on five minutes of spontaneous activity recordings, which were collected with the MC_Rack software at a sampling rate of 25 kHz at 37°C for 5 min, in humidified 5% CO2, 9% O2, as in culture. The recording begins after three weeks of culture in NbActiv4 media (Thermo-Fisher, Carlsbad, CA). Arrays with poor growth or less than 80% active electrodes were rejected (Vakilna 2021).  The four subregions contained neurons micro-dissected from the subregions of the hippocampal formation of postnatal day 4 Sprague-Dawley rats, namely the entorhinal cortex (EC), dentate gyrus (DG), CA3, and CA1+subiculum in order.  Fifty-one microfluidic tunnels ..., , # Data from: Spindle oscillations in communicating axons within a reconstituted hippocampal formation are strongest in CA3 without thalamus

[https://doi.org/10.5061/dryad.fqz612jzz](https://doi.org/10.5061/dryad.fqz612jzz)

MC Rack output files in the form of MCD file types and the associated h5 files. Recordings are 5-minute MEA120 recordings of a self-wiring hippocampus with axonal tunnels. Axonal tunnels are as follows:
A6-A7
B6-B7
C6-C7
D6-D7
E6-E7
F1-G1
F2-G2
F3-G3
F4-G4
F5-G5
H6-H7
J6-J7
K6-K7
L6-L7
M6-M7
F8-G8
F9-G9
F10-G10
F11-G11
F12-G12

Standard MC_Rack raw data outputs used in the MCD files. The h5 files are the hierarchical datafile conversions of the MCD files which are actually used in MATLAB. The names are preserved between the files. Matlab files labeled FIDX_stim associate a file ID used within the code to a file name via loading two MATLAB variables named \"FID\" and \"filename\" as a double and a string, respectively. They are associated as listed below:

FID1=ECDGCA3CA...,