Tag Archives: rhythm

Our body clock is largely kept working by “junk DNA”

The so-called “junk” bits of our DNA is not, after all, quite junk. New research shows that these seemingly inactive genetic elements, micro RNAs (miRNAs), act as a genome-wide time-keeping mechanism, maintaining the function and accuracy of our body clocks. They also make you jet-lagged.

Image via Pixabay.

Until now, research into the origins of our circadian rhythm (body clock) focused on what are known as clock genes — these contain the data for proteins that keep the clock ticking. Judging by this rhythm, our body knows when it’s time to wake up or go to bed, when it’s time to eat, when it falls dark. It then prepares for each of these times, generally by releasing different hormones to prep your body up. Needless to say, this rhythm is a very important adaptation that allows organisms to sync in with their environment.

We’ve been studying its origins in the hope of developing new treatment options for diseases such as Alzheimer’s, cancer and diabetes, but progress has been slow. It may have been that we were looking in the wrong place all along, new research reports.

Clocks in unusual places

“We’ve seen how the function of these clock genes are really important in many different diseases,” said Steve Kay, Provost Professor of neurology, biomedical engineering, and quantitative computational biology at the Keck School of Medicine of the University of Southern California.

“But what we were blind to was a whole different funky kind of genes network that also is important for circadian regulation and this is the whole crazy world of what we call non-coding microRNA.”

Molecular circadian clocks exist in every cell in the body, the team reports. They are small bunches on non-coding nucleotides known as micro RNAS, which can affect the patterns of gene expression by preventing messenger RNA from being turned into proteins. In essence, their job is to stop the protein blueprints from being taken to the factory if it’s not the right time. Past research has hinted at this role of miRNAs, but determining which of the hundreds of such molecules in the genome actually influence the circadian rhythm was quite a challenge.

The team, led by Lili Zhou, a research associate in the Keck School’s Department of Neurology, worked with the Genomics Institute of the Novartis Research Foundation (GNF) in San Diego, which produces robots capable of high throughput experiments. Along with Zhou, they developed a new robot to test almost a thousand miRNAs individually. Each strand was transferred into a cell. These cells were engineered to glow on and off based on their internal clock, which allowed the team to monitor its function.

The next step was to inactivate certain miRNAs identified in the previous step in similar cells. This had an inverse effect on the cells’ behavior than activating the genes — suggesting that their activity is directly involved in maintaining the circadian rhythm, and the previous experiment wasn’t picking up on an unrelated mechanism.

“The collaboration with GNF made it possible for us to conduct the first cell-based, genome-wide screening approach to systematically identify which of the hundreds of miRNAs might be the ones modulating circadian rhythms,” said Zhou.

“Much to our surprise,” added Kay, “we discovered about 110 to 120 miRNAs that do this.”

As for their role on a greater level, the team also studied the physiological and behavioral impacts of miRNAs. They engineered mice with an inactivated miR 183/96/182 cluster, which interfered with their wheel-running behavior in the dark compared with control mice. Further examination of brain, retina, and lung tissue revealed different effects in every tissue — suggesting that the way miRNAs operate is different among tissues.

The findings, the team says, could present a solid launching board for new treatments or prevention avenues for specific diseases.

“In the brain we’re interested in connecting the clock to diseases like Alzheimer’s, in the lung we’re interested in connecting the clock to diseases like asthma,” said Kay.

“The next step I think for us to model disease states in animals and in cells and look at how these microRNAs are functioning in those disease states.”

The paper “A genome-wide microRNA screen identifies the microRNA-183/96/182 cluster as a modulator of circadian rhythms” has been published in the journal Proceedings of the National Academy of Sciences.

What’s the link between music, pleasure, and emotion?

A bad day can be made better with the right jam, and a boring commute is that much more enjoyable with your favorite tune in the background. But why does music have such a powerful impact on us? And why do we like it so much?

Image via Pixabay.

We know that music has a special significance to humanity, as it’s popped up (either independently or through a cultural exchange) in virtually every society in history. We experience that special significance daily when we put our headphones on or relax after work with a nice record.

Back in 2001, researchers at the McGill University in Montreal used magnetic resonance imaging (MRI) to show that people listening to music showed activity in the limbic and paralimbic brain areas, which are related to the reward system. This reward system doles out dopamine, which makes us feel pleasure, as a reward for sex, good food, and so on. Addictive drugs also work by coaxing the production and release of dopamine in the brain.

That being said…

We don’t really know why, to be honest

But we do have a number of theories.

Back in his 1956 book Style and Music: Theory, History, and Ideology, philosopher and composer Leonard Meyer proposed that the emotional response we get from music is related to our expectations. He built on previous theories (the belief-desire–intention model) that the formation of emotion is dependent on our desires. The inability to satisfy some desire would create feelings of frustration or anger but, if we do get what we want, we get nice feelings as a reward. Delayed gratification also makes an appearance here: the greater the split between frustration and when we actually get what we want, the better we will feel once we get it, the theory goes.

In Meyer’s view, because music works with patterns, the human brain subconsciously tries to predict what the next note or groups of notes will be. If it’s right, it gives itself a shot of dopamine as a reward. If it’s not, it will try harder, and get a higher shot of dopamine once it eventually succeeds. In other words, simply having an expectation of how the song should go makes it elicit emotions in our brain, regardless of whether that expectation proves to be right or not.

It’s a nice theory, but it’s very hard to test. The main issue with it is that music can be so diverse that there are virtually endless ways to create and/or go against expectations, so it’s not exactly clear what we should test for. A song can rise or fall quickly, and we may expect a rising song to continue to rise — but it can’t do that indefinitely. We know jarring dissonances are unpleasant, but there also seems to be a cultural factor in play here: what was top of the charts two thousand years ago may sound completely horrendous today. You can listen so some reconstructions of ancient music here and here.

Expectations are in large part driven by how a particular piece we’re listening to has evolved so far, how it compares to similar songs, and how it fits in with all the music we’ve listened to so far. We all have our own subconscious understanding of what music ‘should be’ and it is to a large degree driven by our culture. This is why jazz, a melting pot of musical genres and methods, first sounds a bit off to those unacquainted with it.

Music also seems to have a physiological effect on humans. Past research has shown that our heartbeats and breathing patterns will accelerate to match the beat of a fast-paced track “independent of individual preference”, i.e. regardless of whether we ‘like’ the song. It’s possible that our brains interpret this arousal as excitement through a process called brainwave entertainment.

One other possibility is that music activates the regions of the brain that govern and process speech. As we’re very vocal and very social beasts, we’re used to conveying emotion via speech. In this view, music acts as a specific type of speech and as such can be a vehicle for transmitting emotion. Because we have the tendency to mirror the emotions of others, the song would end up making us ‘feel something’.

Music is a very rich playground — it may very well prove to be infinite. Our enjoyment of it also hinges on a very large number of very subjective factors, further complicating attempts to quantify the experience.

From a scientific point of view, it’s very interesting to ask why music sends chills down our spine. From a personal point of view, however, I’m just very thankful that it can.

Heat and light.

External temperature also influences our circadian rhythms, study reports

It’s not only light that tells our biological clocks it’s time for bed — temperature plays a role, too.

Heat and light.

Image credits Leonardine36 / Pixabay.

Researchers from the University of Michigan report that even mild changes in ambient temperature can influence sleep-wake cycles. The neurons that regulate the body’s circadian clock use thermoreceptors to keep tabs on temperatures outside the body, and use the readings to determine when it’s time for a nap.

The findings help flesh out our understanding of how the mammalian brain regulates wake-sleep cycles; previously, only the influence of light on the circadian rhythm was known.

Chill down, nap on

“Decades of work from recent Nobel Prize winners and many other labs have have actually worked out the details of how light is able to adjust the clock, but the details of how temperature was able to adjust the circadian clock were not well understood,” said Swathi Yadlapalli, first author of the study.

“Going forward, we can ask questions of how these two stimuli are processed and integrated into the clock system, and how this has effects on our sleep behavior and other physiological processes.”

The circadian rhythm, also sometimes referred to as the circadian clock, is a biochemical mechanism that allows living organisms to sync their sleep-wake cycle to the 24-hour cycle of a day. Essentially, it’s our daily rhythm. One of the key factors influencing the workings of this rhythm, perhaps unsurprisingly, are levels of ambient light.

However, temperature also seems to play a big part. Together with Chang Jiang, a postdoctoral researcher at the U-M Department of Mechanical Engineering, Yadlapalli developed an optical imaging and temperature control system. Using it, the duo looked into the neural activity in the circadian clock of fruit flies (Drosophila melanogaster) while they were exposed to heat and cold. Fruit flies were used for the study because the neurons that govern their circadian clocks are strikingly similar to those in humans.

The team reports that colder temperatures excite sleep-promoting neurons, a process which ties external temperature to sleep cycles. Finding such a process in fruit flies suggests these neurons could have similar functionality in humans.

“It looks like clock neurons are able to get the temperature information from external thermoreceptors, and that information is being used to time sleep in the fly in a way that’s fundamentally the same as it is in humans,” Shafer said.

“It’s precisely what happens to sleep in mammals when internal temperature drops.”

Shafer adds that the circadian system creates a daily rhythm in temperature which is an important cue for when nap time comes around. So, while you may think our bodies run at a steady 37°C (98.6°F), “in fact, it’s fluctuating.” As the clock ticks nearer to wakefulness, our circadian system warms the body up. When it’s close to bedtime, it lowers our internal temperature. This effect is independent of the temperature of the room you’re sleeping in.

The paper “Circadian clock neurons constantly monitor environmental temperature to set sleep timing” has been published in the journal Nature.

Infants detect the beat in music 2 days after birth

You’ve grown tired of hearing one of your friends telling you he’s got the music in his blood since the day he was born and you sigh. You’d probably be surprised to find out that a new study proves he is totally right. Unfortunately for him though, there’s nothing special about that: every 2 or 3-day-old baby can detect the beat in music.

Researchers at the Institute for Psychology of the Hungarian Academy of Sciences and the Institute for Logic, Language and Computation of the University of Amsterdam discovered that humans are the only beings who synchronize their behavior to rhythmic sounds. The phenomenon is called “beat induction” and probably led to the creation of the music itself through clapping, dancing using and one’s voice to sing. The phenomenon was not detected in other species such as chimpanzees or the bonobo.

The new findings show that this sense of rhythm is not induced in the first months of life by parents through actions like rocking, as previously believed. Apparently, feeling the music and reacting to it is either innate or learnt in the womb especially as the auditory system is partly functioning about three months before birth. Beat induction is also used later in a child’s life as it allows him or her to adapt to the rhythm of someone’s speech, to know when to answer and use their voice according to the situation.

In order to find these results the babies were given self-adhesive ear-couplers while scalp electrodes were placed on their heads in order to measure their electrical brain signals. A simple, regular rock rhythm consisting of hi-hat, snare and bass drum was delivered to the infants. Other variants, in which strokes on non-significant positions were omitted, were played to the babies with a deviant segment, missing the downbeat. Immediately after each modified segment, their brains produced an electrical response which showed that they were expecting to hear a certain beat, but that did not happen.

Maybe not a total surprise, this study can be an indicator of our evolution and of what it is that makes us human, after all. Could music be the answer?

Source: Universiteit van Amsterdam