134 Sentences With "rhythmicity" | Random Sentence Generator

These findings on daily rhythmicity in microbiota have really piqued my interest because disruption of our circadian rhythmicity by electric light at night has been my research passion for several decades.

The other issue addressed by the AMA statement is the impact on human circadian rhythmicity.

"Even though bacteria live in our gut and in the dark, they in fact show circadian rhythmicity," Segal says.

Almost all life on Earth has an endogenous circadian rhythmicity that is genetically determined, but that also responds to changes in light and dark.

As scientists investigate the links between our internal daily patterns, electric light and health, new information about the rhythmicity of our microbiome might hold clues about how this all works together.

Gut feeling: How your microbiota affects your mood, sleep and stress levels New research is beginning to show that the composition and activity of the microbiota exhibits a daily, or circadian, rhythmicity, just like we do.

"This study is the first large-scale investigation of the association of objectively measured circadian rhythmicity with various mental health, well-being, personality and cognitive outcomes, with an unprecedented sample size of more than 90 000 participants," Doherty wrote in an email.

However, external factors may lead to the disruption of the heart's rhythmicity.

As Alzheimer's disease drastically changes cholinergic function, the circadian system naturally follows the changed levels. Circadian rhythmicity in acetylcholine release is critical for optimal memory processing, and a loss of this rhythmicity contributes to cognitive problems in Alzheimer's disease.

In regards to rhythmicity of the clock in a free running setting PRR9 and PRR5 are associated with longer and shorter periods respectively. For each gene, the double mutant with PRR7 exacerbates observed trends in rhythmicity. The triple mutant renders the plant arrhythmic.

Rhythmicity did disappear, but it took several cycles, and it is unknown why rhythmicity was not immediately abolished. In addition, Block suspects that calcium flux plays a role in the entrainment of the mammalian clock to the environment, similar to its role in mollusk entrainment.

Circadian rhythmicity in Adesmia cancellata L. (Coleoptera: Tenebrionidae) from Kuwait. Journal of Arid Environments 3 319-24.

Future work focusing on understanding the role of circadian rhythms in Drosophila will continue to investigate cycle's role in maintaining rhythmicity.

Cardiac rhythmicity is the spontaneous depolarization and repolarization event that occurs in a repetitive and stable manner within the cardiac muscle. Rhythmicity is often abnormal or lost in cases of cardiac dysfunction or cardiac failure. It is the ability of the heart to maintain a relatively stable relation between its systole and diastole. Not increasing one on the expense of the other.

His research focuses on circadian rhythmicity of vertebrates, including contributing to an understanding of light input pathways on extra-retinal photoreceptors of non-mammalian vertebrates, discovering a mammalian mutation for circadian rhythmicity (tau mutation in golden hamsters), and locating a circadian oscillator in the pineal gland of bird. He has written almost 200 scientific publications."Using PubMed." National Center for Biotechnology Information.

These proteins mediate the oscillating expression of the transcription factor VRILLE (VRI), which is required for behavioral rhythmicity, per and tim expression, and accumulation of PDF (pigment-dispersing factor).

Reppert and colleagues found that the core mechanisms for the SCN in mammals consist of interacting positive and negative transcriptional feedback loops. The first loop is an autoregulatory negative transcriptional feedback loop in which the mCRY proteins negatively regulate mCry and mPer gene transcription. The second interlocking feedback loop involves the rhythmic regulation of Bmal1. Rhythmicity of Bmal1 is not necessary for clockwork function, but it helps modulate the robustness of rhythmicity.

Some flies in each cases showed weak free-running rhythmicity. These results lead the researchers to believe that LNV neurons were the critical circadian pacemaker neurons and that PDF was the principal circadian transmitter.

Temperament is a construct that describes a person's biological response to the environment. Issues such as soothability, rhythmicity, sociability, and arousal make up this construct. Most often sociability contributes to the development of social competence.

Different organisms such as bacteria, plants, fungi, and animals, show genetically based near-24-hour rhythms. Although all of these clocks appear to be based on a similar type of genetic feedback loop, the specific genes involved are thought to have evolved independently in each kingdom. Many aspects of mammalian behavior and physiology show circadian rhythmicity, including sleep, physical activity, alertness, hormone levels, body temperature, immune function, and digestive activity. The SCN coordinates these rhythms across the entire body, and rhythmicity is lost if the SCN is destroyed.

While rhythmicity in the KaiABC oscillator can be reconstituted in vitro, the clock is subject to various additional levels of regulation in vivo. For example, a stoichiometric ratio of clock components must be maintained to preserve rhythmicity. kaiB and kaiC – whose transcript and protein levels oscillate considerable over the course of the day - constitute an operon under the control of a single promoter and are transcribed as a polycistronic mRNA. By contrast, protein levels of KaiA, which lies under the control of an independent promoter, remain fairly across a 24-hour period.

Recent research on cycle has largely focused on the role of circadian rhythmicity in other processes. In 2012, it was reported that aging reduces transcriptional oscillations of core clock genes in the fly head including cycle. Wild type Drosophila show low activity of the CLOCK/CYCLE protein dimer in the morning, and it was recently found that lowering levels of these proteins can affect neuronal signaling. Research from 2012 on sleep architecture and nutrition found that circadian clock mutants, including cyc01 still maintained a normal diet response without circadian rhythmicity.

Multisite Spike-Field Coherence, Theta Rhythmicity, and Information Flow Within Papez's Circuit. In R. P. Vertes & R. W. Stackman (Eds.), Electrophysiological Recording Techniques (Vol. 54, pp. 191-213): Humana Press Inc, 999 Riverview Dr, Ste 208, Totowa, NJ 07512-1165 USA.

These behavioral and physiological observations support the need to consider a 12-hour rhythmicity in the quantification of daily variations in physiological function and some kinds of cognitive performance in fatigue modeling efforts such as the Fatigue Avoidance Scheduling Tool.

Although anatomical details of CPGs are specifically known in only a few cases, they have been shown to originate from the spinal cords of various vertebrates and to depend on relatively small and autonomous neural networks (rather than the entire nervous system) to generate rhythmic patterns. Many studies have been done to determine the neural substrate of locomotor CPGs in mammals. Neural rhythmicity can arise in two ways: "through interactions among neurons (network-based rhythmicity) or through interactions among currents in individual neurons (endogenous oscillator neurons)". A key to understanding rhythm generation is the concept of a half-center oscillator (HCO).

Internal pattern generation operates on a wide range of time scales, from milliseconds to hours or longer. One of the most important types of temporal pattern is circadian rhythmicity—that is, rhythmicity with a period of approximately 24 hours. All animals that have been studied show circadian fluctuations in neural activity, which control circadian alternations in behavior such as the sleep-wake cycle. Experimental studies dating from the 1990s have shown that circadian rhythms are generated by a "genetic clock" consisting of a special set of genes whose expression level rises and falls over the course of the day.

Cardiac arrhythmia arises from abnormalities in action potential formation and propagation through the heart. Changes in electrolyte balance, or development of ectopic pacemaker activity, disrupt normal heart rhythmicity and conduction.Guyton, Arthur C., Hall, John E. (2006). Textbook of Medical Physiology (11th ed.).

However, elimination of the PTO did not fully eliminate the rhythmicity in kaiBC promoter activities, suggesting that the PTO is not necessary in generating rhythms in the TTFL. In truth, the activities of KaiC outside of the PTO is still relatively unknown.

Block has also studied the effect that aging has on the circadian system, collaborating with other leading chronobiologists including Michael Menaker. In 2002, he studied rhythmicity in rats of various ages and found that aging affected rhythmicity differently in different tissues. In the SCN, the intrinsic period shortened with age, while lung tissue often became arrhythmic (showing sporadic activity) and pineal and kidney tissues became phase advanced. In 2008, Block exposed rats of various ages to different light cycles, and found that phase advances took longer in the SCN in old rats than in young rats, but pineal tissues advanced faster in older rats.

Photoreception and entrainment of cockroach activity rhythms. Science 148: 958-959. For rodents, running wheels are easier to set up and automate than other techniques of activity recording such as bar-gnawingMorin, L. 1978. Rhythmicity of hamster gnawing: Ease of measurement and similarity to running activity.

Sequences encoding DUF1220 domains show rhythmicity, resonance and signs of positive selection, especially in primates, and are expressed in several human tissues including brain, where their expression is restricted to neurons. The various HLS domains do not show any interactions as suggested by nuclear magnetic resonance backbone chemical shift analyses.

Vasomotion is the spontaneous oscillation in tone of blood vessel walls, independent of heart beat, innervation or respiration.Haddock RE, Hill CE. Rhythmicity in arterial smooth muscle. J Physiol (Lond ). 2005; 566: 645-656, Aalkaer C, Nilsson H. Vasomotion: cellular background for the oscillator and for the synchronization of smooth muscle cells.

Only the wild-type flies demonstrated rhythmicity in the electrical activity, which indicated that circadian rhythms were present in the olfactory response. In contrast, the mutants showed no cyclic activity. Therefore, Hardin's team discovered that circadian rhythms control the olfactory response in Drosophila antennae and his results were eventually published in Nature.

Mice bred to be heterozygous showed longer periods of 24.4 hours compared to the control 23.3 hour period. Mice homozygous for the mutation showed 27.3 hour periods, but eventually lost all circadian rhythmicity after several days in constant darkness. That showed that "intact Clock genes" are necessary for normal mammalian circadian function .

The Taghert group also demonstrated that PDF signaling influences pacemaker cell synchronicity through PER regulation, identified the PDF receptor, and identified critical PDF receptor signaling components. They have shown that PDF receptor signals differently in different pacemaker groups, and that PDF receptor signaling interact with signals from Cryptochrome (CRY) to help sustain clock rhythmicity.

Oscillations can often be described and analyzed using mathematics. Mathematicians have identified several dynamical mechanisms that generate rhythmicity. Among the most important are harmonic (linear) oscillators, limit cycle oscillators, and delayed-feedback oscillators. Harmonic oscillations appear very frequently in nature—examples are sound waves, the motion of a pendulum, and vibrations of every sort.

"Critical Role for CCA1 and LHY in Maintaining Circadian Rhythmicity in Arabidopsis" Current Biology Vol. 12(9). (2002): 757–761 Plants with non- functioning LHY and CCA1 show a wavy leaf phenotype in constant light conditions. Mutants also have increased vascular pattern complexity in their leaves, with more areoles, branch points and free ends than wild-type Arabidopsis.

In rats, it can be observed in many parts of the brain, including nearly all that interact strongly with the hippocampus. The generation of the rhythm is dependent on the medial septal area: this area projects to all of the regions that show theta rhythmicity, and destruction of it eliminates theta throughout the brain (Stewart & Fox, 1990).

Both the Clock Box and PLRE are involved in achieving maximal light induction, and the Clock Box is essential for maintaining rhythmicity in darkness. Only the ZnF region of WC-2 is required for binding to the PLRE whereas the ZnF regions of both WC-1 and WC-2 are required for binding to the Clock Box.

Okamura collaborated with Gijsbertus T.J. van der Horst and found that both peripheral and central clocks are stopped in Cry deficient mice. Okamura also collaborated with Shin-Ichi Inouye to find that behavioral circadian rhythmicity was recovered when the SCN from wild- type mice was transplanted into Cry deficient mice. This suggests that the suprachiasmatic nucleus (SCN) synchronizes and generates behavioral rhythms.

It is postulated that certain mutant kaiA proteins failed to sustain rhythmicity due to a lack of activation of kaiBC expression. Nishimura found that most KaiA mutations decreased PkaiBC activity to different levels. This is consistent with the finding that kaiA proteins enhance kaiBC activity. His experiment further suggested that kaiA is a part of the phase resetting mechanism of the cyanobacterial clock.

This causes both FRQ expression and DNA binding activity to be significantly impaired. Therefore, these ZnF regions are essential for FRQ expression in light conditions and for WCC circadian function. WC-2 plays a vital role in maintaining the rhythmicity of the circadian pacemaker in fungi. wc-2 null mutants prevent proper frq expression and cause arrhythmicity within the organism.

In 1998, Rosbash et al. discovered the novel clock gene cycle, a homolog of the mammalian Bmal1 gene. Homozygous cycle0 mutants are arrhythmic in locomotor activity and heterozygous cycle0/+ flies have robust rhythms with an altered period of rhythmicity. Western blot analysis shows that homozygous cycle0 mutants have very little PER and TIM protein as well as low per and tim mRNA levels.

In response, the pineal secretes the hormone melatonin. Secretion of melatonin peaks at night and ebbs during the day and its presence provides information about night-length. Several studies have indicated that pineal melatonin feeds back on SCN rhythmicity to modulate circadian patterns of activity and other processes. However, the nature and system-level significance of this feedback are unknown.

VIP and PDF are functional homologs. VIP plays a role in synchronizing and supporting rhythmicity by diverse mammalian SCN pacemakers. Loss of PDF and VIP in free-running conditions resulted in similar behavioral phenotypes: dampened behavioral rhythm with a portion of the knockout mutants showing arrhythmicity. The molecular basis of these phenotypes was a loss in synchrony between pacemaker cells.

They also found that mPer1–3 are widely expressed in tissues outside the brain, including the liver, skeletal muscles, and testis. To determine the function of mPER1–3, Reppert and colleagues disrupted the three genes encoding them. Using double-mutant mice, they showed that mPER3 functions outside the core circadian clockwork, whereas both mPER1 and mPER2 are necessary for rhythmicity.

Bünning, however, proposed that biological clocks are endogenous and synchronize to daily stimuli. Unlike in the hourglass hypothesis, Bünning's hypothesis proposes that circadian rhythmicity derives from an interaction between light and a circadian pacemaker, not external stimuli alone. The general premise of Bünning's hypothesis became a model for circadian time keeping across species off of which many chronobiologists, even into the present, base their models.

In the field of chronobiology, melatonin has been found to be a key player in the synchrony of biological clocks. Melatonin secretion by the pineal gland has circadian rhythmicity regulated by the suprachiasmatic nucleus (SCN) found in the brain. The SCN functions as the timing regulator for melatonin; melatonin then follows a feedback loop to decrease SCN neuronal firing. The receptors MT1 and MT2 control this process.

Lubenov & Siapas, 2009 The trisynaptic circuit is a relay of neurotransmission in the hippocampus that interacts with many brain regions. From rodent studies it has been proposed that the trisynaptic circuit generates the hippocampal theta rhythm. Theta rhythmicity is very obvious in rabbits and rodents and also clearly present in cats and dogs. Whether theta can be seen in primates is not yet clear.

Block and colleagues hypothesized that ion movement across cell membranes plays a role in the generation of circadian rhythms. In 2005, his lab measured rhythms in rat suprachiasmatic nuclei (SCN) in various concentrations of calcium ions. Block found that as calcium concentration decreased, thus lowering the transmembrane ion movement, the amplitude of circadian rhythmicity also decreased. With no calcium added, there was no circadian rhythm at all.

Rhythmicity and contractility of the heart may be normal, but the stiff walls of the heart chambers (atria and ventricles) keep them from adequately filling, reducing preload and end-diastolic volume. Thus, blood flow is reduced, and blood volume that would normally enter the heart is backed up in the circulatory system. In time, restrictive cardiomyopathy patients develop diastolic dysfunction and eventually heart failure.

Deuterium has been shown to lengthen the period of oscillation of the circadian clock when dosed in rats, hamsters, and Gonyaulax dinoflagellates. In rats, chronic intake of 25% D2O disrupts circadian rhythmicity by lengthening the circadian period of suprachiasmatic nucleus-dependent rhythms in the brain's hypothalamus. Experiments in hamsters also support the theory that deuterium acts directly on the suprachiasmatic nucleus to lengthen the free-running circadian period.

The neuropeptide VIP is a homolog of PDF instrumental for cellular and behavioral 24-hour rhythms in mammals. It is expressed in 10 percent of neurons in the SCN. In a study of VIP and VIP receptor 2 (VIPR2) knockout mice, both mutants displayed entrained activity rhythms in light-dark cycle. However, in constant darkness both models displayed poor rhythmicity (very short period), and half of the animals tested were arrhythmic.

In the wild, Cupiennius salei are arboreal, living in trees and bushes, favoring plants such as banana with broad flat leaves and wide joints that provide shelter. Although they tend to generally be inactive, they are much faster than many other arachnids when provoked. Cupiennius salei is a nocturnal, "sit-and-wait" ambush predator behaving with a strong circadian rhythmicity. They hide during daylight, mostly under leaves, and emerge at dusk.

HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported. The current through HCN channels, called the pacemaker current (If), plays a key role in the generation and modulation of cardiac rhythmicity, as they are responsible for the spontaneous depolarization in pacemaker action potentials in the heart. HCN4 isoforms are regulated by cCMP and cAMP and these molecules are agonists at If.

His lyrical expression, idyllic and sentimental, abounds both by the picturesqueness and musicality. He became the first writer in Croatian literature to achieve complete and artistically mature melodiousness and rhythmicity of the Croatian Kajkavian expression. All of his poems were written in Kajkavian literary language, although his vernacular was Kajkavian dialect of Adamovec. He also wrote a number of literary accounts, and a few prosaic notes, chiefly in the spirit of his lyrical interests and stylistic manière.

Early experiments focused on Syrian and Siberian hamsters, ground squirrels, and bubble snails. Since those first publications, experimental subjects represented in the journal have grown to be more diverse, as well as the techniques used to research them. The techniques mentioned in the first few publications involved behavioral and physiological monitoring, circumscribed brain lesions, melatonin radioimmunoassays, electroretinography, and electrophysiological recordings. Early research topics included “splitting,” circannual rhythmicity, photoperiodic time measurement, and circadian pacemaker development, coupling, and output.

There are 3 mutations of 19 mutants (single amino substitutions) found in kaiA found from direct sequencing of the cluster. Thus, the cluster as well as the Kai proteins have necessary functions for the circadian clock of Synechococcus. IPTG induced overexpression of kaiA led to arrhythmicity, demonstrating that rhythmicity requires the expression of kaiA as well as the other genes. Mutagenesis of kaiA reveals that there are rarely short-period mutations, but an abundance of long period mutations.

Rhythmogenesis in a neuron is due to an instability associated with the resting potential. Such instability can be attributed to properties of low- threshold calcium currents. The current is activated at around −60 mV, making it able to generate a low-threshold spike at or near the resting potential. In a somewhat recent finding, cells maintained at a hyperpolarized level have been shown to exhibit intrinsic rhythmicity, resulting in spontaneous oscillatory behavior due to Ca2+ driven depolarizations.

Over time, mounting evidence began to challenge this assertion. For example, discrete temporal separation of photosynthesis and nitrogen fixation observed in cyanobacteria suggested the existence of some mechanism of circadian control. Finally, in 1986 Tan-Chi Huang and colleagues discovered and characterized robust, 24-hour rhythms of nitrogen fixation in Synechococcus cyanobacteria, demonstrating circadian rhythmicity in a prokaryotic species. Following these discoveries, chronobiologists set out to identify the molecular mechanisms governing operation of the cyanobacterial clock.

These mutations cause the peak of the evening activity to occur earlier and later, respectively, compared to wildtype per+ flies. They found that RNA levels for perS and perL1 also display clear rhythmicity. Like locomotor activity the peak expression is shifted earlier for perS and later for perL1. They transformed the period0 null mutation flies with a 7.2-kb piece of functional per DNA, and measured per mRNA levels at the per0 locus and new locus.

The Akhilesh Reddy group has shown, using a range of unbiased -omics techniques (RNA-sequencing, proteomics, metabolomics) that Drosophila S2 cells display circadian molecular rhythms. These cells do not express known "clock genes" including per and tim. Introduction of PER and TIM proteins into the cells does not cause rhythmicity of these cells as read out by abundance or phosphorylation of PER and TIM proteins. These cells were thus regarded as "clock-less" by the fly field until now.

The 20th century saw greatly increased interest in and research on all questions about sleep. Tremendous strides have been made in molecular, neural and medical aspects of biological rhythmicity. Physiology professor Nathaniel Kleitman's 1939 book Sleep and Wakefulness, revised 1963, summarized the existing knowledge of sleep, and it was he who proposed the existence of a basic rest-activity cycle. Kleitman, with his students including William C. Dement and Eugene Aserinsky, continued his research throughout the 1900s.

This gave him the freedom to study the clock through a range of physiological functions from the hatching of fruit flies to rodents' locomotor activities. He performed large series of experiments to demonstrate that circadian rhythmicity is intrinsic and independent of environmental cues. He carried out a famous and protracted debate with Frank Brown, of Northwestern University, on whether circadian timekeeping is intrinsic or environmentally driven. Pittendrigh's data and argument ultimately prevailed and sparked interest in chronobiology.

On this album, Nagelfar combined Northern black metal influences with their own rhythmicity and influences from their Teutonic thrash metal background. The vocals were partly "crazily screamed", partly clean and "heroically sung". The production by Andy Classen, who had never worked with black metal bands before, gave them "a brutal yet 'true' sound". The production, which was "extremely fat and punchy for black metal conditions", is considered "an important building stone for the success of this album".

Simplified Representation of Neurospora Circadian Clock Reflecting its role as a core clock protein, deletion of the frq gene results in arrhythmicity, and in Neurospora, the only function of FRQ is in the circadian clock. The frq gene can be activated from two distinct cis- acting sequences in its promoter, a distal site, the clock-box, used in the context of circadian regulation, and a site close to the principal transcription start site that is used for light-induced expression (the proximal light-regulatory element or PLRE). These frq transcripts both have capacity to encode two FRQ proteins, a long form of 989 amino acids (lFRQ) and a short form of 890 amino acids (sFRQ); both lFRQ and sFRQ are required for strong rhythmicity although the clock is able to persist at certain temperatures, albeit with a weaker rhythmicity, with just one of the proteins present. The choice of which protein is made is the result of temperature- dependent splicing of the primary transcript such that it includes or excludes the ATG start codon for lFRQ.

These currents depolarize the cell further enough to activate NMDA receptors and ICAN, which helps cell regenerate its bursts. The ratio between inward and outward currents helps determine the activity of pacemaker neurons in the pre-Bötzinger complex. The major outward currents involved in the regulation of neuron activity are potassium currents. Although the exact role of potassium currents is still being investigated, it appears that potassium and sodium leak currents are crucial for the rhythmicity of the pre-Bötzinger complex.

KaiB is a gene located in the highly-conserved kaiABC gene cluster of various cyanobacterial species. Along with KaiA and KaiC, KaiB plays a central role in operation of the cyanobacterial circadian clock. Discovery of the Kai genes marked the first-ever identification of a circadian oscillator in a prokaryotic species. Moreover, characterization of the cyanobacterial clock demonstrated the existence of transcription-independent, post-translational mechanisms of rhythm generation, challenging the universality of the transcription-translation feedback loop model of circadian rhythmicity.

And, although removing the pineal gland in many animals abolishes melatonin rhythms, it does not stop circadian rhythms altogether—though it may alter them and weaken their responsiveness to light cues.David R. Weaver (1999), "Melatonin and Circadian Rhythmicity in Vertebrates: Physiological Roles and Pharmacological Effects", in Turek & Zee (eds.), Regulation of Sleep and Circadian Rhythms, pp. 197–262. Cortisol levels in diurnal animals typically rise throughout the night, peak in the awakening hours, and diminish during the day.Eve Van Cauter & Karine Spiegel (1999).

Approximately half of all of the Jrk heterozygotes were arrhythmic, and those that did manifest a rhythm had a slightly longer period than the wild-type controls. Researchers also observed that both PER and TIM levels are extremely low and non-cycling in homozygous Jrk flies, approximately equivalent to the trough levels of wild-type flies. In heterozygotes, PER and TIM cycle well, but the amplitude is reduced by approximately 50%, consistent with the clear effects on behavioral rhythmicity in these flies.

Bearded seals produce distinct trills from late March to late June, with a decline in rhythmicity in late May and June. This timeline coincides with their breeding and pupping season, which is from April to May. The repetitive and transmittable nature of bearded seal trills leads researchers to believe that they are utilized for communication, likely during courtship and breeding. Males use these sounds to establish mating territories and communicate their fitness, but it is likely that females produce these sounds as well.

Lullabies are often used to pass down or strengthen the cultural roles and practices. In an observation of the setting of lullabies in Albanian culture, lullabies tended to be paired with the rocking of the child in a cradle. This is reflected in the swinging rhythmicity of the music. In addition to serving as a cultural symbol of the infant's familial status, the cradle's presence during the singing of lullabies helps the infant associate lullabies with falling asleep and waking up.

Competitors in the World Memory Championships are able to perform outstanding feats of memory and show increased fMRI activation in their retrosplenial cortex than normal controls when doing so. This is thought to be due to their use of a spatial learning strategy or mnemonic device known as the method of loci. The region also displays slow-wave theta rhythmicity and when people retrieve autobiographical memories, there is theta band interaction between the retrosplenial cortex and the medial temporal lobe.

Sometimes, hypnic jerks are mistaken for another form of movement during sleep. For example, hypnic jerks can be confused with restless leg syndrome, periodic limb movement disorder, hypnagogic foot tremor, rhythmic movement disorder, and hereditary or essential startle syndrome, including the hyperplexia syndrome. But some phenomena can help to distinguish hypnic jerk from these other conditions. For example, the occurrence of hypnic jerk arises only at sleep onset and it happens without any rhythmicity or periodicity of the movements and EMG bursts.

But he believes the band already distanced themselves from that on Hünengrab im Herbst; the album "did not sound as black metal did at that time". On their debut album, Nagelfar combined Northern black metal influences with their own rhythmicity and influences from their Teutonic thrash metal background. The vocals were party "crazily screamed", partly clean and "heroically sung". The production by Andy Classen, who had never worked with black metal bands before, gave them "a brutal yet 'true' sound".

This proposed mechanism has been shown to possibly be more complex in that FRQ may regulate WC-1 and WC-2 independently. Recently the transcription factor ADV-1 was identified as a necessary transducer of clock outputs, including circadian rhythmicity in genes critical to somatic cell fusion. The frq gene is strongly induced by short duration exposure to light. Because the core of the clock is based on rhythmic expression of frq, acute light-induction provides a straightforward way to reset the clock.

The Late Elongated Hypocotyl gene (LHY), is an oscillating gene found in plants that functions as part of their circadian clock. LHY encodes components of mutually regulatory negative feedback loops with Circadian Clock Associated 1 (CCA1) in which overexpression of either results in dampening of both of their expression. This negative feedback loop affects the rhythmicity of multiple outputs creating a daytime protein complex. LHY was one of the first genes identified in the plant clock, along with TOC1 and CCA1.

For example, PER1 knockouts affect food entrainable oscillators and methamphetamine-sensitive circadian oscillators, whose periods are altered in the absence of PER1. In addition, mice with knockouts in both the PER1 and PER2 genes show no circadian rhythmicity. Phase shifts in PER1 neurons can be induced by a strong, brief light stimulus to the SCN of rats. This light exposure causes increases in PER1 mRNA, suggesting that the PER1 gene plays an important role in entrainment of the mammalian biological clock to the light- dark cycle.

McMahon’s lab generated transgenic Per1::GFP mice in which a degradable form of recombinant jellyfish GFP reporter is driven by the mouse Per1 gene promoter. mPer1‐driven GFP fluorescence intensity reports light‐induction and circadian rhythmicity in neural structures of the SCN. The Per1::GFP transgenic mouse allows for the simultaneous quantification of molecular clock state and the firing rate of SCN neurons. Thus, this circadian reporter transgene depicts gene expression dynamics of biological clock neurons, providing a novel view of this brain function.

Yogev G, Giladi N, Peretz C, Springer S, Simon ES, Hausdorff JM: Dual tasking, gait rhythmicity, and Parkinson's disease: which aspects of gait are attention demanding? Eur J Neurosci 2005 Exercise: Physical therapy and exercise have been shown to have positive effects on gait parameters in PD patients. Physiotherapists may help improve gait by creating training programs to lengthen a patient's stride length, broaden the base of support, improve the heel-toe gait pattern, straighten out a patient's posture, and increase arm swing patterns.O'Sullivan, S.O. (2007).

He conducted an experiment using rats in which he established several control groups and a test group. Using a Halasz knife and his microsurgery experience gained in prior laboratory work, Moore lesioned the SCN of the mice in the test group. The resulting arrhythmicity in corticosterone levels in these mice compared to the control group’s maintained rhythmicity, revealed the SCN’s function as the master circadian clock. This experiment laid the foundation for numerous other studies into better understanding the role of the SCN in mammalian circadian functions.

The Schwartz research group focused on understanding the neural regulation of circadian rhythmicity in mammals. They focused on tissue, organismal, and supra-organismal levels of analysis to see how individual processes interact in the circadian system to produce observable emergent properties. The Schwartz lab investigated light induced and endogenous gene expression, and the underlying dual oscillatory structure of the circadian pacemaker. His research group has focused on defining the mechanisms by which dysrhythmias occur and how social interactions may impact circuits and cells in the master clock.

His laboratory studies the physiological, cognitive and functional changes resulting from sleep loss in humans. His research has primarily focused on the manner in which sleep homeostasis and circadian rhythmicity control cognitive, affective, behavioral, endocrine and immunological processes. Dinges' work has contributed to our knowledge of the effects of sleep disorders, the recovery potential of naps, the nature of sleep inertia and the impact of cumulative sleep debt. He has developed technologies for monitoring human neurobehavioral capability, such as his patented Psychomotor Vigilance Test (PVT).

Sleep deprivation is even more severe in ICU patients, where the naturally occurring nocturnal peak of melatonin secretion was found to be absent, possibly causing the disruption in the normal sleep-wake cycle. However, as the personal characteristics and the clinical picture of hospital patients are so diverse, the possible solutions to improve sleep and circadian rhythmicity should be tailored to the individual and within the possibilities of the hospital ward. Multiple interventions could be considered to aid patient characteristics, improve hospital routines, or the hospital environment.

Phosphorylation stabilizes WCC and promotes its export to the cytoplasm, effectively down-regulating frq transcription. The White Collar Complex (WCC), the heterodimer of WC-1 and WC-2, acts as a positive element in the circadian clock. WCC serves as an activator of frq gene transcription by binding to two DNA promotor elements in the nucleus: the Clock box (C box) and the Proximal Light-Response Element (PLRE). PLRE is required for maximal light induction, while the C box is required for both maximal light induction and maintaining circadian rhythmicity in constant darkness.

In the laboratory, lake chubs have expressed free-running circadian rhythms that are among the most precise of the few fish species studied to date.Kavaliers, M., 1978, Seasonal changes in the circadian period of the lake chub, Couesius plumbeus, Canadian Journal of Zoology 56: 2591-2596.Kavaliers, M., 1979, Pineal involvement in the control of circadian rhythmicity in the lake chub, Couesius plumbeus, Journal of Experimental Zoology 209: 33-40.Kavaliers, M., 1979, The pineal organ and circadian organization of teleost fish, Revue Canadienne de Biologie 38: 281-292.

Initially, it was thought that a transcription-translation feedback loop was necessary in creating circadian rhythms so it was believed that kaiABC would have this function as well. However, it was later discovered that inhibition of kaiBC mRNA accumulation using a transcription or translation inhibitor did not prevent the circadian cycling of kaiC phosphorylation. Thus, it is the case that cyanobacterial clock rhythmicity is independent of both transcription and translation. Additionally, experiments were conducted to test the self-sustainable oscillation of KaiC phosphorylation, which is important in the regulation of the kaiABC gene cluster.

While all three kai genes are independently required for sustained circadian rhythmicity in cyanobacteria, the kaiA gene is restricted to a group of higher-order cyanobacteria. For example, while the Synechococcus and Prochlorococcus cyanobacterial genera are closely related, kaiA is absent in Prochlorococcus species. Cyanobacteria lacking kaiA demonstrate oscillations in gene expression and cell cycle progression, but these rhythms are not self-sustaining and rapidly disappear under constant conditions. Contrasting cyanobacterial species lacking kai genes, some members of the Synechococcus family express paralogs of kaiB and kaiC referred to as kaiC2, kaiB2, kaiC3, and kaiB3.

HCN channels are sometimes referred to as pacemaker channels because they help to generate rhythmic activity within groups of heart and brain cells. HCN channels are encoded by four genes (HCN1, 2, 3, 4) and are widely expressed throughout the heart and the central nervous system.Kaupp UB, Seifert R. Molecular diversity of pacemaker ion channels (2001) Annu Rev Physiol. 63:235-57. Review. The current through HCN channels, designated If or Ih, plays a key role in the control of cardiac and neuronal rhythmicity and is called the pacemaker current or "funny" current.

This system allowed an exquisitely precise circadian rhythm of luminescence to be measured from cell populations and even from single cyanobacterial cells. The luminescence rhythms expressed by these transformed S. elongatus fulfilled all three key criteria of circadian rhythms: persistence of a 24-hour oscillation in constant conditions, temperature compensation, and entrainment. Thus, the work with various Synechococcus species firmly established that prokaryotic bacteria are capable of circadian rhythmicity, displacing the prior "no circadian clocks in prokaryotes" dogma. Nevertheless, persuasive evidence for circadian programs in bacteria other than the cyanobacteria is still lacking.

Circadian 241x241px KaiC is a gene belonging to the KaiABC gene cluster (with KaiA, and KaiB) that, together, regulate bacterial circadian rhythms, specifically in cyanobacteria. KaiC encodes for the KaiC protein which interacts with the KaiA and KaiB proteins in a post-translational oscillator (PTO). The PTO is cyanobacteria master clock that is controlled by sequences of phosphorylation of KaiC protein. Regulation of KaiABC expression and KaiABC phosphorylation is essential for cyanobacteria circadian rhythmicity, and is particularly important for regulating cyanobacteria processes such as nitrogen fixation, photosynthesis, and cell division.

They were eventually able to localize the gene region causing this rescue, and observed circadian rhythmicity in upstream promotor activity of kaiA and kaiB, as well as in the expression of kaiA and kaiBC messenger RNA. They determined abolishing any of the three kai genes would cause arrhythmicity in the circadian clock and reduce kaiBC promoter activity. KaiC was later found to have both autokinase and autophosphatase activity. These findings suggested that circadian rhythm was controlled by a TTFL mechanism, which is consistent with other known biological clocks.

Cyanobacteria are the simplest organisms with a known mechanism for the generation of circadian rhythms. KaiC ATPase activity is temperature compensated from 25 to 50 degrees Celsius and has a Q10 of about 1.1 (Q10 values around 1 indicate temperature compensation). Because the period of KaiC phosphorylation is temperature compensated and agrees with in vivo circadian rhythms, KaiC is thought to be the mechanism for basic circadian timing in Synechococcus. ∆kaiABC individuals, one of the more common mutants, grow just as well as wild type individuals but they lack rhythmicity.

Upon receiving pineal tissue transplantation, previously arrhythmic sparrows experienced the reestablishment of rhythmicity. In fact, their reestablished circadian oscillations resembled the circadian oscillation pattern for locomotor activity of the donor sparrows. The 20% of the sparrows who had successful transplantations showed temporary arrhythmicity in constant darkness for a period of 10 to 100 days, which was not always evenly distributed in the 24-hour day; the sparrows, however, eventually became rhythmic once again.Zimmerman N.H., Menaker M. The pineal gland: A pacemaker within the circadian system of the house sparrow.

Further investigation of the SCN as a central structure of circadian rhythms by Silver, et al. found that the SCN can control circadian rhythmicity by a diffusive signal. They transplanted the SCN as previously done by Menaker, but they encapsulated the graft thus preventing outgrowth by mutant SCN neurons. Even with the SCN restrained in this way the wild type hamster displayed a shorter period consistent with the period of the SCN donated by the mutant tau hamster, suggesting the SCN emits diffusable factors to control circadian rhythms.

Menaker and colleagues investigated if MASCO affected the molecular feedback loop underlying the currently accepted model for circadian rhythmicity in mammals. This investigation was done by treating arrhythmic mice lacking or with mutations to various genes in this feedback loop with MAP dosages. These genes included mutations and deletions to Per1, Per2, Cry1, Cry2, Bmal1, Npas2, CLOCK and CK1e. All of these mutants continued to respond and exhibit changes in free-running rhythms in the presence of MAP, despite mutational breaks in the feedback loop for circadian oscillation.

Circadian rhythmicity is present in the sleeping and feeding patterns of animals, including human beings. There are also clear patterns of core body temperature, brain wave activity, hormone production, cell regeneration, and other biological activities. In addition, photoperiodism, the physiological reaction of organisms to the length of day or night, is vital to both plants and animals, and the circadian system plays a role in the measurement and interpretation of day length. Timely prediction of seasonal periods of weather conditions, food availability, or predator activity is crucial for survival of many species.

The spiking activity of neurons within the hippocampus is highly correlated with sharp wave activity. Most neurons decrease their firing rate between sharp waves; however, during a sharp wave, there is a dramatic increase in firing rate in up to 10% of the hippocampal population These two hippocampal activity modes can be seen in primates as well as rats, with the exception that it has been difficult to see robust theta rhythmicity in the primate hippocampus. There are, however, qualitatively similar sharp waves and similar state-dependent changes in neural population activity.Skaggs et al.

His early work with mollusks investigated the structure and function of basal retinal neurons (BRN) in circadian photoentrainment. He was the first to discover a cell-autonomous circadian pacemaker and concluded that BRNs are both necessary and sufficient for photoentrainment. Later in his career, Block explored the molecular basis of circadian rhythms in mammals, and found that calcium flux was necessary for circadian rhythmicity. His most recent research, which he is still working on today, is largely focused on the effect that aging has on the circadian clock.

The PDF receptor is necessary for rhythmicity since it acts as a binding site for PDF on the pacemaker or 'clock' neurons. The PDF receptor, along with the receptor of its mammalian homolog, vasoactive intestinal peptide (VIP), is known to be a G-protein-coupled receptor of the B1 subfamily. Flies with mutant PDF receptors are arrhythmic or show weak short-period behavioral rhythms. In a 12:12 light-dark cycle, normal flies exhibited locomotor behavior with a morning peak around dawn and an evening peak around dusk.

This rhythm is thought to be important feature of SCN to synchronize with each other and control rhythmicity in other regions. VIP acts as a major synchronizing agent among SCN neurons and plays a role in synchronizing the SCN with light cues. The high concentration of VIP and VIP receptor containing neurons are primarily found in the ventrolateral aspect of the SCN, which is also located above the optic chiasm. The neurons in this area receive retinal information from the retinohypothalamic tract and then relay the environmental information to the SCN.

A three-phase model is the classical view of the respiratory CPG. The phases of the respiratory CPG are characterized by the rhythmic activity of: (1) the phrenic nerve during inspiration; (2) recurrent laryngeal nerve branches that innervate the thyroarytenoid muscle during the last stage of expiration; (3) the internal intercostal nerve branches that innervate the triangularis sterni muscle during the second stage of expiration. The rhythmicity of these nerves is classically viewed as originating from a single rhythm generator. In this model, phasing is produced by reciprocal synaptic inhibition between groups of sequentially active interneurons.

Rhythmicity in CPG's can also result from time-dependent cellular properties such as adaptation, delayed excitation, and post-inhibitory rebound (PIR). PIR is an intrinsic property that elicits rhythmic electrical activity by depolarizing the membrane once hyperpolarizing stimulus is gone. "It can be produced by several mechanisms including hyperpolarization-activated cation current (Ih) or deinactivation of depolarization-activated inward currents" Once inhibition has ceased, this period of PIR can be explained as the time with increased neuronal excitability. It is the property of many CNS neurons that sometimes results in action potential "bursts" following immediately after inhibitory synaptic input.

Through the T7 cycle, the mice were exposed to light at all circadian phases. Light pulses presented at night lead to expression of the transcription factor c-Fos in the amygdala, lateral habenula, and subparaventricular nucleus further implicating light’s possible influence on mood and other cognitive functions. Mice subjected to the T7 cycle exhibited depression-like symptoms, exhibiting decreased preference for sucrose (sucrose anhedonia) and exhibiting more immobility than their T24 counterparts in the forced swim test (FST). Additionally, T7 mice maintained rhythmicity in serum corticosterone, however the levels were elevated compared to the T24 mice, a trend that is associated with depression.

Following transformation, per mRNA levels were rhythmic at both the original and new locus. The per0 locus was able to transcribe normal per mRNA and translate normal PER protein, meaning that rhythmicity was rescued by functional PER protein transcribed and translated from the 7.2-kb piece of per DNA. There is a feedback loop at play in which cycling of PER protein levels at the new locus feeds back to dictate cycling of per mRNA levels at the original per0 locus. In 1992, Rosbash again collaborated with Jeffrey Hall and Paul Hardin to more closely examine the mechanisms of the TTFL.

The work done by Menaker and colleagues looked at the effects of chronic MAP expression on two strains of intact and SCN-lesioned mice in constant dark and constant light conditions. MAP in the drinking water generated circadian locomotor rhythmicity in SCN lesioned mice. When MAP was removed, the free-running locomotor rhythm persisted for as long as fourteen cycles. This study also showed that small increases in MAP caused an increase in daily wheel-running activity and the length of the circadian period for intact mice and SCN-lesioned mice in constant dark and constant light conditions.

The term circadian was coined by Franz Halberg in 1959. According to Halberg's original definition: In 1977, the International Committee on Nomenclature of the International Society for Chronobiology formally adopted the definition, which states: Ron Konopka and Seymour Benzer identified the first clock mutant in Drosophila in 1971 and called it "period" (per) gene, the first discovered genetic determinant of behavioral rhythmicity. per gene was isolated in 1984 by two teams of researchers. Konopka, Jeffrey Hall, Michael Roshbash and their team showed that per locus is the centre of the circadian rhythm, and that loss of per stops circadian activity.

A role of CKIε has also been seen in humans related to Familial Advanced Sleep Phase Syndrome, in which individuals have a much shorter period than the typical human. In this case, it does not seem to be a mutation of the CKIε protein itself, but instead in the binding site for phosphorylation of the PER2 protein. In addition, kinase activity has been shown to be involved in the nuclear localization of PER and other genes involved in circadian rhythmicity. Therefore, it is this phosphorylation that allows PER to repress its own transcription and place a delay on the circadian system.

Each of these mutations maps to the kinase domain of DBT gene. The short- and long-period alleles of DBT enhance or attenuate, respectively, PER degradation in the nucleus, further demonstrating the importance of timely PER degradation as a critical determinant in establishing 24-h rhythmicity. In addition to influencing protein degradation, DBT affects the timing of nuclear accumulation of PER. The short-period mutant dbtS delays PER nuclear accumulation, which is independent of PER protein stability, and arrhythmic alleles of dbt cause nuclear accumulation of PER in clock-containing cells of larval and adult Drosophila.

The bent-v handshape used in the sign A body of work has arisen looking at the similarities between Black American Sign Language and African-American English (AAVE), since both are language varieties marked by their use in African-American communities. In 1998 John Lewis investigated the incorporation of aspects of AAVE into BASL. He reported that, during narrative storytelling by a Black signer, there were "Ebonic shifts" marked by shifts in posture and rhythmicity and by incorporating side- to-side head movement. He concluded that this "songified" quality was related to the style of AAE.

Cyanobacteria displays a circadian clock system in which three protein oscillators, KaiA, KaiB, and KaiC, constitute a system known as a post-translational oscillator (PTO) that facilitates the oscillation of the larger transcription translation negative feedback loop (TTFL). The TTFL drives gene expression and replenishes KaiA, KaiB, and KaiC, while the PTO constitutes the core of the circadian clock of cyanobacteria. This Kai core confers circadian rhythmicity to ATP hydrolysis activity and kinase/phosphatase activity, both of which are temperature compensated. Additionally, KaiB and KaiC, but not KaiA, have a circadian rhythm of 24 hours in experimental conditions, such as free-running in conditions of constant light.

Whereas rhythms in Per2 promoter activation and Per2 mRNA levels have almost the same phase, Cry1 mRNA production is delayed by approximately four hours relative to Cry1 promoter activation. This delay is independent of CRY1 or CRY2 levels and is mediated by a combination of E/E'-box and D-box elements in the promoter and RevErbA/ROR binding elements (RREs) in the gene's first intron. Transfection of arrhythmic Cry1−/− Cry2−/− double-knockout cells with only the Cry1 promoter (causing constitutive Cry1 expression) is not sufficient to rescue rhythmicity. Transfection of these cells with both the promoter and the first intron is required for restoration of circadian rhythms in these cells.

Hanis, C. L., Ferrell, R. E., Barton, S. A., Aguilar, L., Garza Ibarra, A., Tulloch, B. R., Garcia, C. A., and Schull, W. J. (1983) Diabetes among Mexican Americans in Starr County, Texas. Am. J. Epidemiol. 118:659-672. Other studies concern the genetics of the Aymara tribe in Chile and Bolivia, radiation carcinogenesis in humans, mutations, the genetics and epidemiology of chronic diseases, acheiropodia in Brazil, the adaptation of human populations to high altitudes, the measurement of Darwinian fitness in humans, the genetic structure of human populations, the genetics of night vision, circadian heart rate rhythmicity, the genetics of mental retardation, and cancer risks.

Theta rhythms can be quantified using quantitative electroencephalography (qEEG) using freely available toolboxes, such as, EEGLAB or the Neurophysiological Biomarker Toolbox (NBT). In rats, the most frequently studied species, theta wave rhythmicity is easily observed in the hippocampus, but can also be detected in numerous other cortical and subcortical brain structures. Hippocampal theta waves, with a frequency range of 6–10 Hz, appear when a rat is engaged in active motor behavior such as walking or exploratory sniffing, and also during REM sleep. Theta waves with a lower frequency range, usually around 6–7 Hz, are sometimes observed when a rat is motionless but alert.

A July 2013 study carried out at the University of Basel in Switzerland suggests a correlation between the full Moon and human sleep quality. Professor Cajochen and colleagues presented evidence that a lunar rhythm can modulate sleep structure in humans when measured under the highly controlled conditions of a circadian laboratory study protocol without time cues. Studying 33 volunteer subjects, the researchers found that subjective and objective measures of sleep varied according to lunar phase and thus may reflect human circalunar rhythmicity. Stringently controlled laboratory conditions, in a cross- sectional setting, were employed to exclude confounding effects such as increased light at night or the potential bias in perception.

However, rhythmicity appears to be as important in regulating and coordinating internal metabolic processes, as in coordinating with the environment. This is suggested by the maintenance (heritability) of circadian rhythms in fruit flies after several hundred generations in constant laboratory conditions, as well as in creatures in constant darkness in the wild, and by the experimental elimination of behavioral, but not physiological, circadian rhythms in quail. What drove circadian rhythms to evolve has been an enigmatic question. Previous hypotheses emphasized that photosensitive proteins and circadian rhythms may have originated together in the earliest cells, with the purpose of protecting replicating DNA from high levels of damaging ultraviolet radiation during the daytime.

Rather, endogenous melatonin serves to internalize light cues, making melatonin responsible for modulating neuroendocrine functions. The suprachiasmatic nucleus, or SCN, is a small region within the anterior hypothalamus of the brain that is responsible for orienting the organism’s internal measurement of time to external time cues like daylight. The SCN was first identified to be the "circadian pacemaker" responsible for generating circadian rhythms in 1972. Both Robert Moore at the University of Chicago and Irving Zucker at the University of California, Berkeley linked the SCN to circadian rhythmicity at the same time by lesioning regions of the brain and observing their effects on circadian rhythms.

The Kai proteins that comprise the PTO generate a circadian clock of oscillating phosphorylation/dephosphorylation with a period of around 24 hours. The KaiC protein is an enzyme with two specific phosphorylation sites, Threonine 432 and Serine 431, which express rhythmicity in phosphorylation/dephosphorylation, depending on KaiA and KaiB activity. KaiA stimulates the phosphorylation of KaiC until KaiB sequesters KaiA, initiating dephosphorylation in a determined sequence on Threonine 432 and Serine 431: KaiA stimulates autophosphorylation by KaiC on Threonine 432, and Serine 431 then follows this mechanism of phosphorylation. When both Threonine 432 and Serine 431 are phosphorylated, KaiB binds to KaiC and this complex, KaiBC, then proceeds to block the effect of KaiA.

Spinal nerve Sympathetic ganglion multilingual Microneurography exploration of sympathetic efferent system is unique from technical point of view as multiunit recordings have been very prosperous whereas single unit recording is essential with most other systems. Soon after microneurography was launched it was demonstrated that sympathetic activity is much different in muscle and skin nerves. Instantaneous sympathetic activity in muscle nerves (MSA / MSNA) is heavily controlled by baroreflex mechanisms, resulting in a characteristic cardiac rhythmicity as well as a close and inverse relation to the small variations of blood pressure that normally occur continuously in phase with respiration. In contrast, the sympathetic activity in skin nerves (SSA/SSNA) lacks a tight relation to cardiac and respiratory events.

In 1971, Ron Konopka, a geneticist at the California Institute of Technology, discovered the Period gene, which he found to be involved in the circadian clock of Drosophila. In 1999, Paul Hardin discovered that per mRNA underwent strong circadian oscillations by exposing isolated wild-type per mRNA to a series of light-dark (LD) cycles followed by cycles of constant darkness (DD). As a post-doctorate in the lab of chronobiologist Dr. Michael Rosbash, Hardin specifically noted that per mRNA levels in Drosophila brains fluctuate about 10-fold in a typical 24-hour light-dark cycle. Hardin further demonstrated that wild-type protein, PER, can rescue rhythmicity in the mRNA of an arrhythmic mutant of the per gene.

Schwartz has also researched the effect of social forces on circadian rhythms. His research, conducted with Matthew J. Paul ad Premananda Indic suggests that cohabitation affects the onset of rhythmicity in hamsters, and that changing the speed of the circadian clock is one mechanism by which social factors could alter daily rhythms. In a 2013 paper co-authored with Guy Bloch, Erik D. Herzog and Joel D. Levine, Schwartz shows that social cues may be critical to the adaptive function of circadian rhythms, and can affect them from colony, to organismal, to cellular levels. As of 2017, Schwartz is not running a research lab as he is helping with education at Dell Medical School, University of Texas at Austin.

Takao Kondo, Susan S. Golden, and Carl H. Johnson discovered the gene cluster in 1998 and named the gene cluster kaiABC, as "kai" means “cycle” in Japanese. They generated 19 different clock mutants that were mapped to kaiA, kaiB, and kaiC genes, and successfully cloned the gene cluster in the cyanobacteria Synechococcus elongatus. Using a bacterial luciferase reporter to monitor the expression of clock-controlled gene psbAI in Synechococcus, they investigated and reported on the rescue to normal rhythmicity of long-period clock mutant C44a (with a period of 44 hours) by kaiABC. They inserted wild-type DNA through a pNIBB7942 plasmid vector into the C44a mutant, and generated clones that restored normal period (a period of 25 hours).

The oscillations in the PER and TIM proteins presence causes oscillations in their own and other genes' expression, which is the basis for circadian rhythmicity. The transcription of dbt mRNA and the levels of the DBT protein are consistent throughout the day and not controlled by PER/TIM levels. However, the location and concentration of DBT protein within the cell changes throughout the day. It is consistently present in the nucleus at varying levels, but in the cytoplasm it is predominantly present in the late day and early night, when PER and TIM levels are peaking Before DBT begins phosphorylating PER, a different protein called NEMO/NLK kinase begins phosphorylating PER at its per-short domain.

The parietal eye (very small grey oval between the regular eyes) of a juvenile bullfrog (Rana catesbeiana) Adult Carolina anole (Anolis carolinensis) clearly showing the parietal eye (small grey/clear oval) at the top of its head. Parietal eye of the Merrem's Madagascar swift (Oplurus cyclurus) is surrounded by a black-and-white spot on the skin, giving it the "three-eyed" appearance A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some species of fish, amphibians and reptiles. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation.

The integration of motor and sensory information during walking involves communication between cortical, subcortical, and spinal circuits. Step-like motor patterns of the lower extremities can be induced through activation of the spinal circuitry alone; however, supraspinal input is necessary for functional bipedal walking in humans. Pathologies of the nuclei within the MLR have been associated with a combination of clinical features that are unique to midbrain dysfunction and can be differentiated from other subcortical neurological conditions such as those associated with Parkinsonism and cerebellar lesions. In a clinical case series, three adult males with isolated lesions of the MLR presented with gait hesitation and gait ataxia characterized by stepping that lacked uniform direction, amplitude, and rhythmicity.

Although the theory of central pattern generation calls for basic rhythmicity and patterning to be centrally generated, CPGs can respond to sensory feedback to alter the patterning in behaviorally appropriate ways. Alteration of the pattern is difficult because feedback received during only one phase may require changed movement in the other parts of the patterned cycle to preserve certain coordination relationships. For example, walking with a pebble in the right shoe alters the entire gait, even though the stimulus is only present while standing on the right foot. Even during the time when the left foot is down and the sensory feedback is inactive, action is taken to prolong the right leg swing and extend the time on the left foot, leading to limping.

The term was first coined by in 1978 after it was used in an experiment to determine the effects of jet lag independent of an individual's behavioral cycle - though the methods involved in a constant routine date back to at least 1947. The protocol arose from the well established concept in circadian research that the observation of organisms under constant conditions allows for the illumination of endogenous rhythms, as first described by French scientist Jean-Jacques d'Ortous de Mairan in 1729. In contrast to previous methods, however, the constant routine protocol was developed upon the recognition that several key behaviors exhibiting circadian rhythmicity (including sleep-wake cycle, the behavioral cycle, and the food-intake cycle) also act as masking agents of some endogenous rhythms.

After receiving her master's, Green left Springfield to attend the University of Kansas Medical Center in Kansas City, where she received her Ph.D. in Biochemistry and Molecular Biology working with Simon Kwok. From 1991-1996, she was a Postdoctoral Fellow with Joseph Besharse in the Department of Anatomy and Cell Biology at the University of Kansas Medical Center, where she worked on the molecular mechanisms of circadian rhythmicity in the retinal photoreceptors of Xenopus laevis. In 1997 she joined the faculty in the Department of Biology at the University of Virginia, continuing her work on circadian rhythms in both Xenopus and mammals. More specifically, she studied the molecular and cellular mechanisms that comprise and regulate the circadian oscillator in vertebrates.

Parents may also notice that situational factors cause a child's temperament to seem problematic; for example, a child with low rhythmicity can cause difficulties for a family with a highly scheduled life, and a child with a high activity level may be difficult to cope with if the family lives in a crowded apartment upstairs from sensitive neighbors. Parents can encourage new behaviors in their children, and with enough support a slow- to-warm-up child can become less shy, or a difficult baby can become easier to handle. More recently infants and children with temperament issues have been called "spirited" to avoid negative connotations of "difficult" and "slow to warm up". Numerous books have been written advising parents how to raise their spirited youngsters.

Changes in the positioning of plant leaves over the course of the day were observed as early as the 4th century B.C. by Androsthenes, Alexander the Great’s historian. This phenomenon, however, was not researched further until 1729 when Jean-Jacques d'Ortous de Mairan provided experimental data that mimosa plants close their leaves at night, a movement that persists rhythmically in constant darkness. In 1875, Wilhelm Pfeffer, Bünning’s role model, put forward that these movements might be controlled by an endogenous biological clock. This theory formed the foundation for Bünning’s later work. Prior to Bünning’s work, the prevailing hypothesis on circadian rhythms was the "hourglass" hypothesis, which postulates that circadian rhythmicity within an organism is entirely driven by the external light-dark cycle and that an organism's "hourglass" is reset each day.

Evidence for TCD comes from Magnetoencephalography (MEG), and Electroencephalography (EEG) recordings on the scalp as well as local field potential (LFP) recordings in the patients' thalamus during surgery. Analysing the power spectra reveals increased coherence as well as increased bicoherence in the power spectra in the theta band compared to healthy controls. This indicates a close coupling of cortex and thalamus in the generation of the pathological theta rhythmicity. The thalamic loss of input or gated activity allows the frequency of the thalamo-cortical column to slow into the theta or delta band, and this defeats the lateral inhibition, so faster Gamma band activity appears surrounding the area of slower alpha seen in the theta band, with the theta associated with negative symptoms and the Gamma for positive symptoms.

Subthreshold oscillation frequency can vary, from few Hz to over 40 Hz, and their dynamic properties have been studied in detail in relation to neuronal activity coherence and timing in CNS, in particular with respect to the 10 Hz physiological tremor that controls motor execution, Theta rhythm in the entorhinal cortex,Alonso, A. andgwmw> Llinas, R. (1989) "Subthreshold Na+-dependent theta-like rhythmicity in entorhinal cortex layer II stellate cells". Nature, 342: 175-177., gamma band in cortical inhibitory interneurons and gamma band activity in cortical inhibitory interneuronsLlinas R. Grace, A.A. and Yarom, Y. (1991) " In vitro neurons in mammalian cortical layer 4 exhibit intrinsic oscillatory activity in the 10 to 50 Hz frequency range". PNAS, 88, 897-901 and in thalamus neurons.

Although there were a few earlier hints, the first clear description of regular slow oscillations in the hippocampal EEG came from a paper written in German by Jung and Kornmüller (1938). They were not able to follow up on these initial observations, and it was not until 1954 that further information became available, in a very thorough study by John D. Green and Arnaldo Arduini that mapped out the basic properties of hippocampal oscillations in cats, rabbits, and monkeys (Green and Arduini, 1954). Their findings provoked widespread interest, in part because they related hippocampal activity to arousal, which was at that time the hottest topic in neuroscience. Green and Arduini described an inverse relationship between hippocampal and cortical activity patterns, with hippocampal rhythmicity occurring alongside desynchronized activity in the cortex, whereas an irregular hippocampal activity pattern was correlated with the appearance of large slow waves in the cortical EEG.

The general focus of the Green Lab is to understand the molecular mechanism of the mammalian circadian clock and how it mediates rhythmicity within the physiology, biochemistry, and behavior of an organism. Her lab currently has three main projects: identifying targets and mechanisms of expression regulation of the Nocturnin gene; identifying the mechanism of metabolic control of Nocturnin knockout lean mice; and defining structural components of the repressor protein Cryptochrome and how regulation of the nuclear entry of the protein contributes to circadian period length. Green has formal training in cell biology, biochemistry, and molecular biology, which has given her a broad skill set to further expand her areas of study such as genomics, proteomics, structural biology, and metabolic studies over the course of her career. Aside from her scientific focuses, she also contributes to the greater science community. At the June 23–28, 2019 Gordon Research Conference, “Clocks in Model Organisms: Circadian Networks, Physiology and Health,” she is organizing the “GRC Power Hour,” a panel designed to promote diversity and inclusion for women and minorities in the STEM field as well as encourage the professional growth of all members from all communities by providing a space for discussion and mentorship.