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In my culture, it is advised to provide ablations to the sun three times a day. It is known as त्रिकाल संध्या. Sunrise, noon and sunset.

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Life on Earth follows the rising and setting of the sun. Daily cycles have been found in animals, plants, fungi and even bacteria. For humans, sleeping and waking as well as hormone levels, body temperature and cognitive performance, follow a daily cycle.

Such a wonderful code of execution associated with movement of the sun. When you spend time with the Sun on transition times, I am sure the mental focus helps to switch on and off bodily daily cycles.

Scientists at Washington University School of Medicine in St. Louis have discovered that different groups of neurons, those charged with keeping time, became active at different times of day despite being on the same molecular clock.

Experiment and experience.

The biological control for these daily cycles is known as the circadian clock. In animals, a master circadian clock in the brain helps coordinate most of these body rhythms, including the sleep-wake cycle.

Scanning fruit fly brains helps understanding of neural signaling involved in some circadian behaviors

The biochemical basis of the circadian clock has been conserved through evolution. It involves a small number of “clock proteins” whose levels go up and down in a controlled manner once a day.

 


Research


Shedding light on the day-night cycle

Scanning fruit fly brains helps understanding of neural signaling involved in some circadian behaviors

Life on Earth follows the rising and setting of the sun. Daily cycles have been found in animals, plants, fungi and even bacteria. For humans, sleeping and waking as well as hormone levels, body temperature and cognitive performance, follow a daily cycle.

“The influence of our circadian rhythms can be substantial – for example, some of us are night owls and others are morning larks,” said senior investigator Paul Taghert, PhD, professor of neuroscience. “It’s important to understand how such fundamental timing information is translated into actual neuronal signals in the brain that control daily rhythms, including rhythmic behavior.”

The biological control for these daily cycles is known as the circadian clock. In animals, a master circadian clock in the brain helps coordinate most of these body rhythms, including the sleep-wake cycle.

The biochemical basis of the circadian clock has been conserved through evolution. It involves a small number of “clock proteins” whose levels go up and down in a controlled manner once a day.

To answer that question, Liang performed whole brain scans of living fruit flies every 10 minutes for 24 hours. Fruit flies are widely used in circadian research because the clock in each fly’s tiny brain is represented by only 150 time-keeping or so-called pacemaker neurons, making it much easier to dissect than the clock in larger animals. Even in mice, for example, the circadian system involves about 20,000 pacemaker neurons in a part of the brain called the suprachiasmatic nucleus.

The experiments measured calcium levels inside pacemaker cells to assess the cells’ activities – higher calcium levels indicate higher levels of neuronal activation. Unexpectedly, each pacemaker group displayed a distinct phase of activity.  These activity patterns were sensitive to environmental signals, such as day length, and also to the circadian clock. The researchers found that one specific group of pacemaker neurons was active about four hours before the fly’s morning peak in activity, and another specific group was active about four hours before the fly’s evening activity.

“Essentially, groups of neurons decide to take different parts of the clock,” explained Holy. “One group says, ‘We’ll be active in the morning, to make the fly active that time of day,’ and this other group of neurons says, ‘Even though our molecular clock is peaking here in the morning, we’re going to wait to be most active until later on in the day.’”

 

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