Integration of Biological Clocks and Rhythms

Abstract

Animals, plants, and microorganisms exhibit numerous biological rhythms that are generated by numerous biological clocks. This article summarizes experimental data pertinent to the often-ignored issue of integration of multiple rhythms. Five contexts of integration are discussed: (i) integration of circadian rhythms of multiple processes within an individual organism, (ii) integration of biological rhythms operating in different time scales (such as tidal, daily, and seasonal), (iii) integration of rhythms across multiple species, (iv) integration of rhythms of different members of a species, and (v) integration of rhythmicity and physiological homeostasis. Understanding of these multiple rhythmic interactions is an important first step in the eventual thorough understanding of how organisms arrange their vital functions temporally within and without their bodies.

Effect of simulated tidal currents on the burrow emergence rhythms of the Norway lobster (Nephrops norvegicus)

“…Such a phenomenon was clearly observed in only a few individuals (n = 4). Interestingly, splitting (the presence of two separate phase components 180° apart) in mammalian model organisms is usually observed in a minority of tested individuals (Refinetti 2006). The optimization of physiological processes through the spectral coordination of diel and tidal rhythms has not received sufficient attention (Refinetti 2012), but it could be used as a determinant to assess the ecological significance of biological rhythms.…”

“…Interestingly, splitting (the presence of two separate phase components 180° apart) in mammalian model organisms is usually observed in a minority of tested individuals (Refinetti 2006). The optimization of physiological processes through the spectral coordination of diel and tidal rhythms has not received sufficient attention (Refinetti 2012), but it could be used as a determinant to assess the ecological significance of biological rhythms. Finally, we cannot exclude the possibility that a higher current speed and lower light intensity (simulating deeper water) could be more effective in eliciting such phenomena in a higher proportion of lobsters.…”

“…A Chi-square periodogram (Sokolove and Bushell 1978) was used to scan for significant (P < 0.05) periodicity in the 600-1600 min range (equivalent to 10-27 h) within the whole time series (29.5 days), and the percentage of variance (%V) was reported as a measure of the robustness of the rhythmic patterns (Refinetti 2006). Then, periodogram analysis was repeated for the lobsters that had shown a clear effect of the currents on their locomotor activity in their actograms.…”

Training the Conductor of the Brainwave Symphony: In Search of a Common Mechanism of Action for All Methods of Neurofeedback

“…It is based on rewards and inhibits, which are aspects of conventional EEG frequency training, but these concepts no longer make sense at such low frequencies (the current Cygnet software, version 2.0.7.4, can now filter out frequencies as low as 0.0001 mHz, which is approximately one cycle per 116 days). Even though there are biorhythms that are as slow and slower than the current limit of detection by this EEG amplifier [95], there are no known neural or glial origins of these very slow oscillations, causing controversy over the source of the signal [65,76,97]. However, a recent study demonstrated that 20 sessions of ILF neurofeedback training increased the power of all of the ILFs (≤ 0.1 Hz), including the typical peak around 0.01-0.1 Hz, which is called the infra-slow oscillation (ISO) and correlates with the BOLD signal [98,99].…”

“…The most well-known method is fMRI training, which monitors the BOLD signal in brain structures with high spatial resolution [91][92][93]. Other hemodynamic-based methods that are less well-known are hemoencephalographic (HEG) training and functional near-infrared spectroscopy (FNIRS) training, which have less spatial resolution than fMRI but greater than that of EEG [67,94,95]. FMRI neurofeedback has the greatest number of gold standard RCTs, likely due to the fact that the principal investigators on those studies typically are medical doctors and tend to receive more funding than nonmedical doctors [91,93].…”