Skip to main content
. 2014 Jun 20;9(6):e100536. doi: 10.1371/journal.pone.0100536

Figure 4. Cross-correlation analysis of cardiovascular coupling.

Figure 4

Panels A–C show cross-correlation functions (CCF) between low-frequency (<0.8 Hz) spontaneous fluctuations of heart period (HP) and systolic arterial pressure (SAP) computed during WAKE, NREMS and REMS during 48 hours including light and dark periods. Data are means ± SEM for KO and WT mice fed a SD or a HFD, with n = 9–10 per group. Panel D summarizes the interpretation of CCF results [21]. Negative time shifts indicate that changes in HP follow SBP. A positive CCF peak at negative time shifts (e.g. cardiac slowing after SAP rises), is consistent with baroreflex buffering of SAP changes caused by fluctuations of vascular resistance. A negative CCF trough at positive time shifts (e.g. cardiac acceleration before SAP rises) is consistent with central autonomic commands acting on the heart. Statistical analysis (panels A–C) was performed on the correlation coefficients at the CCF peak (maximum positive) and trough (minimum negative) values. Detailed ANOVA results are reported in Table S3. For abbreviations and symbols see Figures 1 and 3.