El ‘baile’ de una célula del oído “al compás del reloj”

En el siguiente video se puede apreciar como una célula ciliada externa* del oído responde al ser expuesta a la canción “Al compás del reloj”:

* El oído humano en su parte más interna consta de dos tipos de células sensibles al sonido: las células ciliadas internas y las externas. Las internas detectan las ondas sonoras y las transforma en señales eléctricas para que viajen por el nervio auditivo hasta el cerebro donde son interpretadas como sonido. Las externas actúan como un controlador del volumen, es decir como un amplificador de la señal.

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En el Universo todo se mueve y con ritmo

Crédito de la imagen: Rhys Taylor of http://www.rhysy.net/

Sobre la superficie de la Tierra tenemos el movimiento de traslación de esta alrededor del Sol, que es de unos 108.000 kilómetros por hora, y el de rotación, que puede ser de hasta 1.700 kilómetros por hora en el ecuador. 

Y al igual que los planetas giran alrededor del Sol, este gira en torno al núcleo de nuestra galaxia. 

El Sol gira alrededor del núcleo de la Vía Láctea a unos 792.000 kilómetros por hora y a pesar de esa aparentemente descomunal velocidad tarda unos 225 millones de años en completar una órbita. 

La misma Vía Láctea, y con ella el Sol, se mueve a unos 2,1 millones de kilómetros por hora más o menos en dirección al cúmulo de Leo y de Virgo.

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Veery thrush songbird of North America singing with swing / El pájaro tordo (mirlo) Veery de los Estados Unidos, cantando con swing

In the following audio clips you can hear how the veery swings in the same way that human musicians do / En los siguientes audios pueden escuchar al Veery cantando a la manera que lo hace un músico humano.


Here’s the veery at normal speed / Este es su canto a velocidad normal:



When the veery’s song is slowed down you can spot how it swings / Cuando el canto es disminuido en su velocidad se puede apreciar cómo es que el Veery canta con swing:



Es interesante notar cómo esta ave logra mantener el ritmo y la entonación en cada repetición.... definitivamente son aves con muy buen oído, muy afinadas y con pulso de reloj.

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Nuestros miles de relojes corporales / Our thousands of body clocks

Nuestro cuerpo tiene miles de relojes (no solo el que está en el cerebro) que orquestan cuidadosamente el funcionamiento de nuestros tejidos y órganos, desde el corazón, los pulmones hasta el hígado.

Estos relojes no sólo nos sirven para comer regularmente, sino también conlleva a que las diferentes partes del cuerpo se sintonicen para trabajar de manera óptima en determinados momentos del día. Cuando estos relojes se desincronizan puede traer consecuencias graves. Por el contrario, es necesario aprender a aprovechar estos ritmos.

By Allison Aubrey

March 10, 2015

We've long known about the master clock in our brains that helps us maintain a 24-hour sleep-wake cycle.

But in recent years, scientists have made a cool discovery: We have different clocks in virtually every organ of our bodies — from our pancreas to our stomach to our fat cells.

"Yes, there are clocks in all the cells of your body," explains Fred Turek, a circadian scientist at Northwestern University. "It was a discovery that surprised many of us."

We humans are time-keeping machines. And it seems we need regular sleeping and eating schedules to keep all of our clocks in sync.

Studies show that if we mess with the body's natural sleep-wake cycle — say, by working an overnight shift, taking a transatlantic flight or staying up all night with a new baby or puppy — we pay the price.

Our blood pressure goes up, hunger hormones get thrown off and blood sugar control goes south.

We can all recover from an occasional all-nighter, an episode of jet lag or short-term disruptions.

But over time, if living against the clock becomes a way of life, this may set the stage for weight gain and metabolic diseases such as Type 2 diabetes.

"What happens is that you get a total de-synchronization of the clocks within us," Turek says, "which may be underlying the chronic diseases we face in our society today."

So consider what happens, for instance, if we eat late or in the middle of the night. The master clock — which is set by the light-dark cycle — is cuing all other clocks in the body that it's night. Time to rest.

"The clock in the brain is sending signals saying: Do not eat, do not eat!" says Turek.

But when we override this signal and eat anyway, the clock in the pancreas, for instance, has to start releasing insulin to deal with the meal. And, research suggests, this late-night munching may start to reset the clock in the organ. The result? Competing time cues.

"The pancreas is listening to signals related to food intake. But that's out of sync with what the brain is telling it to do," says Turek. "So if we're sending signals to those organs at the wrong time of day — such as eating at the wrong time of day — [we're] upsetting the balance."

And there's accumulating evidence that we may be more sensitive to these timing cues than scientists ever imagined.

Consider, for instance, the results of a weight-loss study that we reported on, which was published in the International Journal of Obesity. Researchers found that the timing of meals can influence how much weight people lose.

"The finding that we had was that people who ate their main meal earlier in the day were much more successful at losing weight," says study author Frank Scheer, a Harvard neuroscientist who directs the Medical Chronobiology Program at Brigham and Women's Hospital.

In fact, early eaters lost 25 percent more weight than later eaters — "a surprisingly large difference," Scheer says. Another study found that eating a big breakfast was more conducive to weight loss, compared with a big dinner — adding to the evidence that the timing of meals is important.

Beyond weight management, there's evidence that the clocks in our bodies — and the timing of our sleeping, eating and activities — play multiple roles in helping us maintain good health. And different systems in the body are programmed to do different tasks at different times.

For instance, doctors have long known that the time of day you take a drug can influence its potency. "If you take a drug at one time of day, it might be much more toxic than another time of day," Turek says. Part of this effect could be that the liver is better at detoxifying at certain times of day.

Turek says his hope is that, down the road, circadian science will be integrated into the practice of medicine.

"We'd like to be in a position where we'd be able to monitor hundreds of different rhythms in your body and see if they're out of sync — and then try to normalize them," Turek says.

Whether — or how quickly — this may happen is hard to say. But what's clear is that the study of the biology of time is exploding.

"What we're doing now in medicine is what Einstein did for physics," says Turek. "He brought time to physics. We're bringing time to biology."

The irony, of course, is that this insight comes at a time when the demands of our 24/7 society mean more and more of us are overriding our internal clocks.

Fuente: http://www.npr.org/sections/thesalt/2015/03/10/389596946/circadian-surprise-how-our-body-clocks-help-shape-our-waistlines

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Un reloj maestro que también controla nuestra temperatura corporal

El área del cerebro conocida como el núcleo supraquiasmático (SCN por su siglas en inglés) es el reloj maestro del cuerpo. Utiliza la luz para sincronizar los ritmos del cuerpo con la noche y el día. Controla directamente los ciclos de sueño / vigilia pero indirectamente controla otros procesos, como el hambre y la sed, y lo hace mediante el control del termostato del cuerpo, el área preóptica del cerebro.

A clump of just a few thousand brain cells, no bigger than a mustard seed, controls the daily ebb and flow of most bodily processes in mammals — sleep/wake cycles, most notably. Now, Johns Hopkins scientists report direct evidence in mice for how those cell clusters control sleep and relay light cues about night and day throughout the body.

A summary of their study of the brain region known as the suprachiasmatic nucleus, or SCN, will be published online in the journal Current Biology on Dec. 22.

“Light has a strong, negative and direct effect on sleep in humans. We experience this every evening when we turn out the lights before we go to bed and every morning when we open the curtains to let light in. However, very little was known about how this happens. Learning that the SCN is indeed required for light to directly regulate sleep is an important piece of the circadian rhythm puzzle,” says Seth Blackshaw, Ph.D., professor of neuroscience at the Johns Hopkins University School of Medicine. “Our chances of finding treatments for people with sleep disorders, or just jet lag, improve the more we understand the details about how sleep is controlled.”

Blackshaw says scientists have known for a while that the SCN functions as a master clock to synchronize sleep and other so-called circadian rhythms in humans and other mammals. But its importance in the more immediate regulation of sleep, like when a bright light wakes someone up, remained debatable because the experiments needed to show its role in a living animal were essentially impossible. “If you surgically removed the SCN in mice, their sleeping and waking were no longer immediately influenced by light, but you can’t remove the SCN without also severing the optic nerve that brings light information to it from the retina. So no one knew if this resistance to light was due to the missing SCN or the missing optic nerve,” says Blackshaw.

In experiments first reported several years ago, Blackshaw’s team found a way to disrupt the normal function of the SCN without physically removing it and damaging the optic nerve. The researchers were trying to identify genes involved in the development of the mouse hypothalamus, the area of the brain that includes the SCN. They identified one such gene, dubbed LHX1, that seemed to be the earliest to “turn on” in the development of the fetal SCN.

For the new round of experiments, the scientists used a customized genetic tool to delete LHX1 just from cells that make up the SCN. They found that the mice experienced severely disrupted circadian rhythms, although they could still be weakly synchronized to light cycles. And the cells of the SCN no longer produced six small signaling proteins known to coordinate and reinforce their efforts, a biochemical process known as coupling.

Whether the mice were kept in constant light, constant darkness or normal cycles of both, their sleep times and duration became random. Cumulatively, they slept for the same amount of time, about 12 hours each 24-hour period, like normal mice, but there was no pattern to the cycle.

“This experiment showed that the SCN is critical to light’s immediate effect on sleep,” says Blackshaw.

The scientists also noticed that in the SCN-impaired mice, core body temperatures didn’t cycle normally. The average body temperature for humans is 37 degrees Celsius, but it fluctuates throughout the day by about 1 degree Celsius, being highest in the afternoon and lowest just before dawn. A similar pattern occurs in mice. These small temperature fluctuations can have a big influence on processes that occur outside the brain that are also under circadian control, such as glucose usage and fat storage, and it has been speculated that they may be the main way by which the SCN controls these bodily rhythms.

In contrast, one of the hallmarks of the body’s circadian processes, including cycles in core body temperature, is that they aren’t generally disturbed by large temperature changes. “Otherwise, you would feel jet-lagged every time you got a fever,” says Blackshaw. But it wasn’t clear from mouse experiments if the SCN was responsible for this resistance to strong temperature changes in living animals. Normal SCN cells in the lab keep cycling in synchrony without regard to temperature pulses, but research from another group showed that they could be “reset” by temperature changes if they could no longer signal to each other.

Knowing that the SCN cells in their LHX1-deficient mice were similarly impaired, a graduate student in Blackshaw’s lab, Joseph Bedont, reasoned that their mice might now be able to return to normal temperature cycles if given pulses of heat.

To try that, they injected the mice — kept in the dark — with a molecule found in bacterial cell walls, which makes them run a fever in response to the perceived threat. Fever is a first-line infection fighter in humans as well. As suspected, their regular core temperature cycling came back.

“These results suggest that the SCN is indeed responsible for the temperature resistance of circadian rhythms in live animals, and it shows us how important SCN coupling is,” says Blackshaw. “It also bolsters the idea that the body’s other physiologic cycles, such as hunger and hormone secretion, are synchronized by the SCN through its regulation of core body temperature.”

Additional experiments identified several molecules that may be directing these vital signals. The Blackshaw team plans to follow up by studying each one to determine their roles. With that information, drug developers will have a better idea which component to target and how. To treat jet lag, for example, Blackshaw says that one hypothetical option would be to briefly block LHX1 so that the SCN cells uncouple and become easier to reset, either by light or temperature. But no one knows yet if that plan would produce undesirable side effects or the desired outcomes.

Fuente: http://neurosciencenews.com/fever-jet-lag-5798/

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El rítmico y simétrico Hexágono de Saturno

El Hexágono que se aprecia en el polo norte de Saturno, rota alrededor de su centro a casi exactamente el mismo ratio en que el mismo planeta rota sobre su eje.

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Your Rhythmic Brain

A través de células madre han podido extraer cómo es que las neuronas funcionan de manera rítmica.

Recently, neuroscientists at the Salk Institute used stem cells to generate diverse networks of self-contained spinal cord systems in a dish, dubbed circuitoids, to study this rhythmic pattern in neurons. The work, which appears online in the February 14, 2017, issue of eLife, reveals that some of the circuitoids–with no external prompting–exhibited spontaneous, coordinated rhythmic activity of the kind known to drive repetitive movements.

“It’s still very difficult to contemplate how large groups of neurons with literally billions if not trillions of connections take information and process it,” says the work’s senior author, Salk Professor Samuel Pfaff, who is also a Howard Hughes Medical Institute investigator and holds the Benjamin H. Lewis Chair. “But we think that developing this kind of simple circuitry in a dish will allow us to extract some of the principles of how real brain circuits operate. With that basic information maybe we can begin to understand how things go awry in disease.”

Nerve cells in your brain and spinal cord connect to one another much like electronic circuits. And just as electronic circuits consist of many components, the nervous system contains a dizzying array of neurons, often resulting in networks with many hundreds of thousands of cells. To model these complex neural circuits, the Pfaff lab prompted embryonic stem cells from mice to grow into clusters of spinal cord neurons, which they named circuitoids. Each circuitoid typically contained 50,000 cells in clumps just large enough to see with the naked eye, and with different ratios of neuronal subtypes.

With molecular tools, the researchers tagged four key subtypes of both excitatory (promoting an electrical signal) and inhibitory (stopping an electrical signal) neurons vital to movement, called V1, V2a, V3 and motor neurons. Observing the cells in the circuitoids in real time using high-tech microscopy, the team discovered that circuitoids composed only of V2a or V3 excitatory neurons or excitatory motor neurons (which control muscles) spontaneously fired rhythmically, but that circuitoids comprising only inhibitory neurons did not. Interestingly, adding inhibitory neurons to V3 excitatory circuitoids sped up the firing rate, while adding them to motor circuitoids caused the neurons to form sub-networks, smaller independent circuits of neural activity within a circuitoid.

“These results suggest that varying the ratios of excitatory to inhibitory neurons within networks may be a way that real brains create complex but flexible circuits to govern rhythmic activity,” says Pfaff. “Circuitoids can reveal the foundation for complex neural controls that lead to much more elaborate types of behaviors as we move through our world in a seamless kind of way.”

Because these circuitoids contain neurons that are actively functioning as an interconnected network to produce patterned firing, Pfaff believes that they will more closely model a normal aspect of the brain than other kinds of cell culture systems. Aside from more accurately studying disease processes that affect circuitry, the new technique also suggests a mechanism by which dysfunctional brain activity could be treated by altering the ratios of cell types in circuits.

Fuente: http://neurosciencenews.com/rhythm-parkinsons-6114/

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