Data from: 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 in the feedback axons from CA3 to DG.
Spindle dissociation from spiking activity and recording in single axons
from isolated hippocampal neurons suggests that spindle mechanisms are
independent of action potentials and that consolidation of
declarative-cognitive memories in the hippocampus may be separate from the
more easily accessible consolidation of memories related to thalamic motor
function.