Abstract
Heartbeat fluctuations in mammals display a robust temporal structure characterized by scale-invariant/fractal patterns. These scale-invariant patterns likely confer physiological advantage because they change with cardiovascular disease and these changes are associated with reduced survival. Models of physical systems imply that to produce scale-invariant patterns, factors influencing the system at different time scales must be coupled via a network of feedback interactions. A similar cardiac control network is hypothesized to be responsible for the scale-invariant pattern in heartbeat dynamics, although the essential network components have not been determined. Here is shown that scale-invariant cardiac control occurs across time scales from minutes to ∼24 h, and that lesioning the mammalian circadian pacemaker (suprachiasmatic nucleus; SCN) completely abolishes the scale-invariant pattern at time scales >∼4 h. At time scales <∼4 h, the scale invariance persisted following SCN lesion but with a different pattern. These results indicate previously unrecognized multiscale influences of the SCN on heart rate fluctuations that cannot be explained by a simple pacemaker of 24-h rhythmicity. The conclusion is that the SCN serves as a major node in the cardiac control network and imparts scale-invariant cardiac control across a wide range of time scales with strongest effects between ∼4 and 24 h. These results demonstrate that experimental manipulations (e.g., SCN lesion) can be used to begin to model and understand the origin of scale-invariant behavior in a neurophysiological system.
Original language | English (US) |
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Pages (from-to) | 265-273 |
Number of pages | 9 |
Journal | Journal of biological rhythms |
Volume | 23 |
Issue number | 3 |
DOIs | |
State | Published - Jun 2008 |
Externally published | Yes |
Keywords
- Cardiac control
- Feedback interactions
- Network
- SCN lesion
- Scale-invariant patterns
- The suprachiasmatic nucleus (SCN)
ASJC Scopus subject areas
- Physiology
- Physiology (medical)