Data from: Spatiotemporal patterns of neocortical activity around hippocampal sharp-wave ripples

A prevalent model is that sharp-wave ripples (SWR) arise ‘spontaneously’
in CA3 and propagate recent memory traces outward to the neocortex to
facilitate memory consolidation there. Using voltage and extracellular
glutamate transient recording over widespread regions of mice dorsal
neocortex in relation to CA1 multiunit activity (MUA) and SWR, we find
that the largest SWR-related modulation occurs in retrosplenial cortex;
however, contrary to the unidirectional hypothesis, neocortical activation
exhibited a continuum of activation timings relative to SWRs, varying from
leading to lagging. Thus, contrary to the model in which SWRs arise
‘spontaneously’ in the hippocampus, neocortical activation often precedes
SWRs and may thus constitute a trigger event in which neocortical
information seeds associative reactivation of hippocampal ‘indices’. This
timing continuum is consistent with a dynamics in which older, more
consolidated memories may in fact initiate the hippocampal-neocortical
dialog, whereas reactivation of newer memories may be initiated
predominantly in the hippocampus.