Oscillatory rhythms in different frequency ranges mark different behavioral states and are thought to provide distinct temporal windows that coherently bind cooperating neuronal assemblies. However, the rhythms in different bands can also interact with each other, suggesting the possibility of higher-order representations of brain states by such rhythmic activity. To explore this possibility, w...

Nature is full of nonlinearities, responsible for a great variety of responses in natural systems. Physiological rhythms constitute a central characteristic of life, which is motivating the analysis of dynamical aspects related to natural systems. Natural rhythms could be either periodic or irregular over time and space and, each kind of dynamical behavior may be related to both normal and path...

Circadian rhythms in physiology and behavior are regulated by a master clock resident in the suprachiasmatic nucleus (SCN) of the hypothalamus, and dysfunctions in the circadian system can lead to serious health effects. This paper reviews the organization of the SCN as the brain clock, how it regulates gonadal hormone secretion, and how androgens modulate aspects of circadian behavior known to...

Our brain activity demonstrates amazing stability across multiple time frames ranging from a few milliseconds to several hours. The longer cycles are commonly called ultradian rhythms and they correspond to infralow frequencies (ILFs) in the milli-Hz range (0.001 Hz). Ultradian rhythms between 90 minutes and 2 hours or longer are readily observed in our electroencephalogram, and they reflect pe...

Monosodium glutamate (MSG) was administrated subcutaneously to wistar rats for 60 days and circadian rhythms of thiobarbituric acid reactive substances (TBARS) and antioxidants such as superoxide dismutase (SOD), reduced glutathione (GSH), catalase, glutathione peroxidase (GPX) and Vitamin-E were studied. Advanced acrophase of TBARS and delayed acrophase of antioxidants were found in experiment...

BACKGROUND The circadian clock of Drosophila is able to drive behavioral rhythms for many weeks in continuous darkness (DD). The endogenous rhythm generator is thought to be generated by interlocked molecular feedback loops involving circadian transcriptional and posttranscriptional regulation of several clock genes, including period. However, all attempts to demonstrate sustained rhythms of cl...

In mammals, a light-entrainable clock located in the suprachiasmatic nucleus (SCN) regulates circadian rhythms by synchronizing oscillators throughout the brain and body. Notably, the nature of the relation between the SCN clock and subordinate oscillators in the rest of the brain is not well defined. We performed a high temporal resolution analysis of the expression of the circadian clock prot...

Animals, plants, fungi and even some prokaryotic organisms display daily rhythms in behavior, physiology, metabolic activity and gene expression. These rhythms are not passively driven by environmental cycles (e.g. light and temperature) but are controlled by endogenous circadian clocks that keep time even in the absence of environmental time cues. Environmental cycles are nevertheless required...

Previous research showed that age-related division of labor in honey bees is associated with changes in activity rhythms; young adult bees perform hive tasks with no daily rhythms, whereas older bees forage with strong daily rhythms. We report that this division of labor is also associated with differences in both circadian rhythms and mRNA levels of period, a gene well known for its role in ci...