Distinct Brain Systems Support Afferent and Efferent Autonomic Activity

Figure 1. Two types of RMSSD time series paired with whole-brain BOLD signals. Modeling individual BOLD time series at TR with RMSSD time series over two 10-second windows before and after TRs allows us to investigate bidirectional relationships between RMSSD and brain BOLD activity. By correlating at-TR BOLD signals with before-TR RMSSD while accounting for after-TR RMSSD, we can examine how changes in RMSSD influence changes in BOLD activity. Likewise, by correlating at-TR BOLD signals with after-TR RMSSD while accounting for before-TR RMSSD, we can investigate how changes in RMSSD are influenced by changes in BOLD activity.

Figure 2. Brain regions (blue) associated with time-varying RMSSD during emotion regulation. Throughout the whole scan, BOLD activity in the ACC, anterior insula, and posterior insula showed negative correlations with RMSSD for younger adults. Neither negative nor positive correlations were found for older adults.

Figure 3. Functionally afferent and efferent brain regions for younger (A) and older adults (B). Blue clusters were negatively correlated with before-TR RMSSD, and orange clusters were positively correlated with after-TR RMSSD. The dark red color indicates the overlap between the blue and orange clusters.

Figure 4. Difference between younger and older adults in afferent and efferent regions. Blue clusters were negatively correlated with before-TR RMSSD, and orange clusters were positively correlated with after-TR RMSSD.

Figure 5. Cross-correlations between BOLD series from afferent and efferent regions. On the X axis, negative values (e.g. −4 TR or −9.6 seconds) mean that in the analysis the afferent BOLD series precedes the efferent BOLD series by that amount (e.g. by 4 TRs or 9.6 seconds), and positive values (e.g. +2 TR or +4.8 seconds) mean the efferent BOLD series precedes the afferent BOLD series (e.g. by 2 TRs or 4.8 seconds). Cross-correlation coefficients at different time lags were plotted with standard error bars, and their significance (corrected P < .001) was indicated by asterisks. The dotted blue line is the skew normal distribution curve fitted to the mean cross-correlation coefficients separately for younger and older adults.