Temporal correlation of the slow sleep envelopes (based on the firing rates) between
different nodes and of the BOLD signal. First row top panels: Correlation of the
envelopes of the slow sleep waves between a specific seed (left posterior cingulate,
lPC) and all cortical areas, for 5 snapshots corresponding to different levels of Ach
(ζ = 0, 0.42, 0.57, 0.71, and 1, from left to right, respectively).
Second row panels: Correlation of the underlying fMRI BOLD signal, for the same seed and
for the same 5 snapshots. Only half hemisphere is shown. Bottom panels (left): Total
correlation (summed over all areas) between the envelopes of the slow sleep waves for
the same seed as a function of the Ach level. Bottom panel (right): Correlation between
the envelopes of the slow sleep waves for each cortical area and for the same seed as a
function of the Ach level.