【Native Speaker每日综合训练—44系列】【44-03】科技 Internal clock

cherry6891

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Part I: Speaker

How Its Internal Clock Is Read, Knows Reindeer
In a study in the journal Current Biology, researchers show that reindeer, and probably other Arctic animals, go without a circadian clock in an environment of weeks-long day or night. Christopher Intagliata reports
March 18, 2010

Humans are pegged to a 24-hour cycle. We're locked into it not just by day and night—there’s the master timepiece in the brain called the circadian clock. But it doesn't make sense to live by a 24-hour clock in the Arctic, where it's dark or light for months at time. The solution? Lose the daily clock. Which is exactly what reindeer seem to have done, according to a study in Current Biology.

Reindeer don't sleep eight hours like we do, and there's no obvious 24-hour pattern to their lives. They just chomp on tundra, nap a few hours and feast again. But they still need to know when to mate, pack on fat or thicken their coats. So they probably rely on an annual clock instead, set by the hormone melatonin.

In humans melatonin levels rise at night, in response to darkness and cues from the circadian clock. In reindeer, even if they’re missing a circadian clock, melatonin levels still spike when it's dark and drop when it's light, making the equinoxes an ideal time to synchronize their annual clocks.

So ask a reindeer what time of year it is, and it may be able to give you the date. Just don't be offended if it won't give you the time of day.(音频已修正)
source:
http://www.scientificamerican.com/podcast/episode/how-its-internal-clock-is-read-know-10-03-18/
[Rephrase 1, 1'15'']

cherry6891

Part II: Speed

Your Brain Has 2 Clocks
How do you sense the passing of time?
November 26, 2013 |By Emilie Reas
Time2
Did you make it to work on time this morning? Go ahead and thank the traffic gods, but also take a moment to thank your brain. The brain’s impressively accurate internal clock allows us to detect the passage of time, a skill essential for many critical daily functions. Without the ability to track elapsed time, our morning shower could continue indefinitely. Without that nagging feeling to remind us we’ve been driving too long, we might easily miss our exit.

But how does the brain generate this finely tuned mental clock? Neuroscientists believe that we have distinct neural systems for processing different types of time, for example, to maintain a circadian rhythm, to control the timing of fine body movements, and for conscious awareness of time passage. Until recently, most neuroscientists believed that this latter type of temporal processing – the kind that alerts you when you’ve lingered over breakfast for too long – is supported by a single brain system. However, emerging research indicates that the model of a single neural clock might be too simplistic. A new study, recently published in the Journal of Neuroscience by neuroscientists at the University of California, Irvine, reveals that the brain may in fact have a second method for sensing elapsed time. What’s more, the authors propose that this second internal clock not only works in parallel with our primary neural clock, but may even compete with it.

Past research suggested that a brain region called the striatum lies at the heart of our central inner clock, working with the brain’s surrounding cortex to integrate temporal information. For example, the striatum becomes active when people pay attention to how much time has passed, and individuals with Parkinson’s Disease, a neurodegenerative disorder that disrupts input to the striatum, have trouble telling time.[296 words]

Time3
But conscious awareness of elapsed time demands that the brain not only measure time, but also keep a running memory of how much time has passed. Scientists have long known that a part of the brain called the hippocampus is critically important for remembering past experiences. They now believe that it might also play a role in remembering the passage of time. Studies recording electrical brain activity in animals have shown that neurons in the hippocampus signal particular moments in time. But the hippocampus isn’t always necessary for tracking time. Remarkably, people with damage to their hippocampus can accurately remember the passage of short time periods, but are impaired at remembering long time intervals. These findings hint that the hippocampus is important for signaling some – but not all – temporal information. If this is the case, what exactly is this time code used for, and why is it so exclusive?

In their new study, the researchers tried to unravel this mystery by training rats to discriminate between different time intervals. They then rewarded the rats with treats when they indicated, by choosing between different odors, that they could tell how much time had passed. Before some of the trials the scientists injected a chemical that temporarily inactivates the hippocampus. This allowed them to test whether a functional hippocampus is necessary to distinguish between different time intervals.

The rats with inactive hippocampi could tell the difference between vastly different time intervals (e.g., 3 versus 12 minutes) just as well as the control rats, but performed no better than chance at detecting differences between similar periods of time (e.g., 8 versus 12 minutes). This suggests that the hippocampus is important for distinguishing between similar time intervals, but isn’t needed when the intervals are very different. But oddly enough, this pattern only held up at long time periods; rats with nonfunctional hippocampi were not just normal at discriminating between similar time periods at short scales (e.g., 1 versus 1.5 minutes), but they in fact performed better.[332 words]

Time4
So while the hippocampus does signal elapsed time, it has a very particular role in doing so. It specifically discriminates between similar time periods at long time scales – on the order of several minutes. When you can tell that you’ve been showering for 10 minutes, and not 15, you can thank your hippocampus. But when you sense the difference between 1 and 1.5 minutes, or 20 minutes and an hour, other brain regions have taken over as internal time-keeper.

While it may seem odd for the hippocampus to perform such a highly specialized function, this is perfectly consistent with what we know it does in other domains. The hippocampus is renowned for its ability to discriminate between overlapping objects or experiences – a process known as pattern separation. This study suggests it pattern separates many features of an experience, detecting subtle differences between objects, places and time periods.

The hippocampus might be oblivious to events that happen on a second-by-second scale, but we’re certainly able to track the rapid passage of these moments. Considering that the striatum is believed to track time on the order of seconds, the authors propose that the hippocampus and striatum might actually compete with one another, such that when the hippocampus is quieted, the striatum is freed to function even more effectively than usual. Although I wouldn’t advise intentionally damaging your hippocampus (you’ll develop a significantly graver problem), doing so could theoretically boost your ability to track the passage of short time periods.

But it’s unclear whether this inhibitory relationship is reciprocal or unidirectional. If the hippocampus and striatum indeed function as separate, antagonistic clocks, does the striatum suppress the hippocampus, just as the hippocampus appears to impair the striatum? Scientists know that damaging the striatum leads to a host of problems processing time. But could it also confer one particular time-telling superpower – that of distinguishing between similar long time intervals - by launching the hippocampus into high-gear? Only further research will tell.

So when you make it to work on time tomorrow, acknowledge not just one, but your multiple inner clocks, and rest easy you have a healthy hippocampus.[354 words]
Source：
http://www.scientificamerican.com/article/your-brain-has-two-clocks/


New Drug Targets Promise to Treat Jet Lag
Molecular clues may reveal how to instantly reset the brain's clock
Jun 12, 2014 |By William Skaggs
Time5
Jet lag is a pain. Besides the inconvenience and frustration of traveling more than a few time zones, jet lag likely causes billions of dollars in economic losses. The most effective treatment, according to much research, is structured exposure to light, although the drug melatonin may also sometimes be helpful at bedtime.

Both approaches have been used for more than 20 years, and during that time no viable new interventions have appeared.
Recently, however, research into the molecular biology of circadian rhythms has raised the prospect of developing new drugs that might produce better results.

Jet lag occurs when the “biological clock” in the brain becomes misaligned with the local rhythm of daily activity. The ultimate goal of circadian medicine is a treatment that instantly resets the brain's clock. Failing that, it would be helpful to have treatments that speed the rate of adjustment. Four recent discoveries suggest new possibilities.

The first involves vasopressin, which is the main chemical signal used to synchronize cellular rhythms of activity in the brain area that is responsible for our biological clock. Blocking vasopressin makes it much easier to reset this clock. Potentially, a drug that interferes with vasopressin could work as a fast-acting treatment for jet lag.

The second and third possibilities involve a pair of brain chemicals called salt-inducible kinase 1 (SIK1) and casein kinase 1ε (CK1ε), both of which limit the ability of light to reset the brain's clock. Drugs already exist that interfere with their action and greatly increase the effectiveness of light exposure. The existing drugs are not viable jet-lag treatments, because they are hard to administer and have unpleasant side effects, but researchers hope better drugs can be developed that work in a similar way.
The strongest possibility in the near term involves the neurotransmitter serotonin. In addition to its well-known roles in mood and motivation, serotonin operates inside the brain's clock. Evidence from small studies suggests that several drugs that act on the serotonin system can speed up recovery from jet lag, including 5-HTP, the metabolic precursor for serotonin, which is widely available as a “nutritional supplement.” Scientists have not yet run a gold standard clinical trial to test the supplement's effectiveness, however.

Research on circadian biology is moving at such a rapid pace that other possibilities will surely emerge in the near future. Travelers can start looking forward to reclaiming the first days of their trips.[400 words]

source:
http://www.scientificamerican.com/article/new-drug-targets-promise-to-treat-jet-lag/

Blind Cavefish Stops Its Internal Clock
The eyeless cavefish saves energy by freezing its circadian rhythm
Time6
Some creatures will go to great lengths just to save a little energy. Take the blind Mexican cavefish; this super-efficient animal uses almost 30 percent less energy to survive than its counterparts in surface waters, and it accomplishes this in a rather interesting way, a new study suggests.

The blind Mexican tetra or cavefish (Astyanax mexicanus) saves energy by forgoing circadian rhythms, according to researchers at Lund University in Sweden. Sometimes referred to as an internal clock, circadian rhythms help many organisms — including animals, plants, fungi and even certain bacteria — coordinate their behavior and physiology with the day-night cycle, according to study researcher Damian Moran, a postdoctoral student in the Lund University department of biology.

This clock provides one of its most important functions by controlling metabolism, or the chemical reactions involved in maintaining healthy cells and breaking down molecules to gain energy. Circadian rhythm helps ensure these reactions occur in advance of when an organism will most need energy, Moran told Live Science.

"It takes time to make proteins and the things that are needed to help us digest, to run or to see, so by having a clock mechanism that is tuned to your environment, you can get your metabolism ready in advance of when you may need it," Moran said. Humans, he added, do this while they sleep.

But unlike most organisms, blind Mexican cavefish don't control their metabolism with a circadian clock, the researchers found. The scientists learned this after comparing the metabolic rate, or rate of oxygen consumption, of cave-dwelling A.mexicanuswith that of surface-dwelling A. mexicanus.

The researchers exposed both kinds of fish to light-dark conditions that mimicked a 24-hour day, as well as conditions of total darkness. They found the surface-dwelling fish consumed more oxygen during daylight hours, even in the absence of any daylight.

"This is the same as if you or I were put in a dark room for a couple of days," Moran said. "We would show this kind of cycle, because we have this clock inside our bodies."[338 words]

[the rest]However, the cave-dwelling fish did not exhibit the same behavior. Regardless of whether it was light or dark, the fish consumed roughly the same amount of oxygen, the researchers found. By forgoing the circadian rhythms that control metabolism, the blind Mexican cavefish was able to expend nearly 30 percent less energy in a 24-hour period than its surface-dwelling counterparts.

"We know they save a lot of energy, and that's good if you're living in a cave, because caves tend to be quite food limited," Moran said. The blind Mexican cavefish has evolved other distinctive characteristics that make it better suited to living in a pitch-black environment. Most notably, the creature doesn't have any eyes.

But it's the absence of an internal clock that Moran and his colleagues are most interested in at the moment. And they're not alone. Earlier this year, researchers from University College London and the National Autonomous University of Mexico published a study in the journal Nature Communications, which similarly showed that blind Mexican cavefish lack normal circadian rhythms.
"Not only do we not really know that much about circadian energy use in animals in general, we don't even know how to consider animals that don't have these circadian rhythms," Moran said. "We tend to assume that these rhythms are always adaptive, that they serve some really important purpose. But what happens in animals that don't have these cycles? It's a real conundrum."      [236 words]
source:
http://www.scientificamerican.com/article/blind-cavefish-stops-its-internal-clock/

cherry6891

Part III: Obstacle

Why Does Time Fly as We Get Older?
By Jordan Gaines Lewis | December 18, 2013 |

Another year; another Christmas around the corner.

The conversation around the watercooler these days has evolved into the annual “where has the time gone?” discussion—how quickly the neighborhood kids have become high school graduates; how our hot July beach vacations seem like they were just yesterday; and how we haven’t baked cookies or sent cards or bought gifts yet because time has just been flying by.

It’s become a common complaint—almost a joke—that time seems to whiz by faster and faster as we get older.

Of course, aging doesn’t grant us the power to disrupt the space-time continuum, so it’s not a real problem. But why do we perceive it to be?

Psychologist William James, in his 1890 text Principles of Psychology, wrote that as we age, time seems to speed up because adulthood is accompanied by fewer and fewer memorable events. When the passage of time is measured by “firsts” (first kiss, first day of school, first family vacation), the lack of new experiences in adulthood, James morosely argues, causes “the days and weeks [to] smooth themselves out…and the years grow hollow and collapse.”

In the early 1960s, Wallach and Green studied this phenomenon in groups of younger (18-20 years) and older (median age 71 years) subjects through the use of metaphors. Young people were more likely to select static metaphors to describe the passage of time (such as “time is a quiet, motionless ocean”). Older folks, on the other hand, described time with swift metaphors (“time is a speeding train”). In research by Joubert (1990), young subjects, when asked, said that they expect time to pass more rapidly when they become older.

In the first study (2005) to examine the subjective passage of time across the lifespan, Marc Wittman and Sandra Lehnhoff of Ludwig-Maximilian University Munich recruited 499 participants ranging in age from 14-94. Each subject filled out a series of questionnaires. The first part included questions on a Likert-type scale (ratings from -2 to +2) with answers ranging from time passing “very slowly” to “very fast.” The second part consisted of statements and metaphors about the passage of time, and subjects were asked to rate each sentence from 0 (“strong rejection”) to 4 (strong approval”).

Unexpectedly, Wittman and Lehnhoff found a weak association between age and the individuals’ perception of time; in other words, everybody, regardless of age, thought that time was passing quickly. The question, “How fast did the last 10 years pass for you?” yielded a tendency for the perception of the speed of time (in the last decade, anyway) to increase with age; this pattern peaked at age 50, however, and remained steady until the mid-90s. Questions regarding smaller intervals of time (“How fast did the last hour/week/month pass?”) did not change with age.

When it came to metaphors, folks between ages 20-59 were more likely to select statements referring to “time pressure,” or the notion that time is speeding by and that one can’t finish all they want to do in the time allotted. Wittman and Lehnhoff reason that people in this age range (but not teenagers or the elderly) are most likely to be in the midst of professional and family duties, resulting in the feeling that once can’t keep up with life’s demands.

In 2010, William Friedman (Oberlin College) and Steve Janssen (Duke University) expanded upon these findings. In this study, 49 undergraduate students and 50 older adults (aged 60-80 years) were given a list of twelve newsworthy events of the past decade and asked to rate a.) when the event occurred, and b.) how well they remembered each event. They also completed the same Likert scale as in Wittmann and Lehnhoff’s study to assess their perception of the speed of time.

While subjects in both age groups reported a good memory for all twelve events, young adults were more likely to underestimate age of the event. Furthermore, these individuals replicated Wittmann and Lehnhoff’s findings that while both age groups perceived short periods of time (i.e. hours, weeks, months) similarly, older adults reported that the last 10 years passed more quickly than young adults.

In an extension of this study published in July of this year, Friedman, Janssen, and Makiko Naka (Hokaido University in Japan) found that among those individuals who felt that they were currently experiencing significant time pressure, time was passing quickly on short time intervals (i.e. weeks, months). Those who felt time pressure over the past decade, on the other hand, felt that the previous ten years had passed in a flash.

Two conclusions appear to ring true: 1.) While age is certainly a factor, the notion of “time pressure” contributes significantly to our perception of time, across all age groups, and 2.) Time pressure is cross-cultural; the results of these studies were similar among the German, Austrian, Dutch, Japanese, and New Zealander participants.

So, what’s going on here? Why does it seem like Christmas 2012 was just last week when, as a child, it seemed to take ages to arrive?

We’ll probably never know why, exactly, but psychologists have put forth some interesting theories:

1. We gauge time by memorable events.
As William James hypothesized, we may be measuring past intervals of time by the number of events that can be recalled in that period. Imagine a 40-something mom experiencing the repetitive, stressful daily grind work and family life. The abundant memories of her high school years (homecoming football games, prom, first car, first kiss, graduation) may, compared to now, seem like much longer than the mere four years that they were.

2. The amount of time passed relative to one’s age varies.
For a 5-year-old, one year is 20% of their entire life. For a 50-year-old, however, one year is only 2% of their life. This “ratio theory,” proposed by Janet in 1877, suggests that we are constantly comparing time intervals with the total amount of time we’ve already lived.

3. Our biological clock slows as we age.
With aging may come the slowing of some sort of internal pacemaker. Relative to the unstoppable clocks and calendars, external time suddenly appears to pass more quickly.

4. As we age, we pay less attention to time.
When you’re a kid on December 1, you’re faithfully counting down the days until Santa brings your favorite Hot Wheels down the chimney. When you’re an adult on December 1, you’re a little more focused on work, bills, family life, scheduling, deadlines, travel plans, Christmas shopping, and all of that other boring adult stuff. The more attention one focuses on tasks such as these, the less one will notice the passage of time.

5. Stress, stress, and more stress.
As concluded by Wittmann and Lehnhoff (and replicated by Friedman and Janssen), the feeling that there is not enough time to get things done may be reinterpreted as the feeling that time is passing too quickly. Even older individuals (who are, more often than not, retired from work) may continue to feel similarly due to physical handicaps or diminished cognitive ability.

While the feeling may be inescapable, appease yourself by knowing that time is not literally getting faster as you age. Take a moment to slow down this Christmas, enjoy time with your family and friends, and be assured that the fancy Rolex that Santa brings you next Wednesday is doing its job just fine.[1226 words]

source:
http://blogs.scientificamerican.com/mind-guest-blog/2013/12/18/why-does-time-fly-as-we-get-older/

tantan08

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conglomerator

Time 2: 1:43

You need to thank to your brain for make it on time. Scientists used to think that we have one single clock in our brain to count elapsed time, but emerging research shows that we may a second clock not only working in parallel with the primary one, but also competing with it. Past research suggested how our brain works to remind us of time.

Time 3: 2:14

Scientists found that we not only need to measure time but also need to remember how much time passed. So experiments about hippocampus were taken by using rats to study what is the role  that hippocampus plays in remembering time. Some research results are acquired.

Time 4: 2:17

Hippocampus is proved to be useful to discriminate similar time periods at long time scales, while striatum is proved to be useful to discriminate track time on the order of seconds. And actually, the two are competing with each other. But the inhibitory relationship is reciprocal or unidirectional is unclear. But at least, you have multiple inner clocks to thank to for making it on time.

Time 5: 2:46

Jet lag is a pain. We have something to help with it, but not effective. There is new hope to have something more effective. The ultimate goal is to reset our inner clock. Four discoveries suggest the new possibilities. 1, 2, 3 are discussed. I could find the 4th…

Time 6: 1:53

Some creatures will go to great length to save a little energy. The blind Mexican cavefish does it in a very particular way. We have a inner clock to get us ready before we do something. But The blind Mexican cave fish does have the clock. Not having this clock helps the fish save a lot of energy. We know very little about the clock’s function, so we know even less how animals behave when they don’t have the clock.

Obstacle: 5:27

Why we feel time is passing by quicker as we grow older. Scientists have took several experiments but no conclusive answers are made and we might never know the answers. But some experiments are described and some interesting theories are presented.

cyndichiang

Speaker
Scientists found that reindeers eat plants which can release toxic chemicals and that animal's saliva prevent the production of toxic substance secreted by plants.
Fungus in the plant promote the chemical that can make animals lose their lamps,but comound of animal's saliva interfere with chemical signals and decrease the production of toxic substance.
This phenomenon is unsolved but we now know that mammales' seliva is more important than previously realized

Obstacle; 4'45''
Researchers found that people perceive time passing more fast as we get old.
A survey shows that when people are at 50,this feeling is at peak and that people aged between 20-59 refer to statement"time pressure" since they are midst of their duties.
This "time pressure" is a worldwide phenomenon,which is interpreted by many theories.

成成儿

谢谢cherry6891，貌似audio贴错了～～

FortMI

Speaker: Reindeer dont sleep, but they still mate, pack on the fat or thicken on the coats, because Reindeer lose the daily clock but rely on the annual clock set by the M.....
T2:1'49" Brain has two neural clocks. one internal neural clocks makes people process different types of time. but it is too simple. the second new discovered clock even compete with the first one.
T3: 1'54" Brain not only measure time, but also remember the pass of time. The substance: Hippocampus is important to remember past experience, and it is not  necessary for tracking time always, (short time experience can remember, long time not) Then one trial on rats shows that H is important to tell similar time intervals not very different ones.and this is also for normal.
T4: 1'58"H works very specific area for tracking time. Striatum is for tracking time, too,  then the H compete with S.  When H rest, S begin ork more effeicte than usual. But it isnt clear the relationship between T and S is reciprocal or unidirectional. this need more research.

seraph797979

cherry6891 发表于 2014-11-3 22:09
Part II: Speed
Your Brain Has 2 Clocks
How do you sense the passing of time? ...

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5,2’25
6，1‘59

成成儿

生病两天没做阅读，速度果然是慢了好多。
【time 1】3'
human has a 24 hours circle, but article animals such as reindeer do not have such a pattern.
but research finds that reindeer does certain thing in certain time of a year.
so they conclude that reindeer has a annual cycle.   

【time 2】3'
human have an inner clock. the past research showed that the inner clock was generated by a simple neural clock.
however, a new study indicates that there has a second clock which is parallel with the first simple neural clock.

【time 3】3'07''22'''
this part talks about what is the essential factor of human to perceive time and remember time passing.
researcher indicates that hippocampus not only can remember the past events but also may remember the passing time.
the first experiment shows that unfunctional hippocampus can remember passing time in short time like functional hippocampus.
the second experiment shows that in the long time, hippocampus is important to distinguish similar intervals.
but in the short time, unfunctional hippocampus perform better.

【time 4】4'
this art conclude that hippocampus can distinguish the similar intervals in a long time scales.
hippocampus is essential for remember overlapping events.
further study is needed that
does hippocampus help people to distinguish intervals in a short time scales after hippocampus is suppressed by striatum.

【time 5】3'57''37'''
this article is about the solution of Jet Lag which causes economic loss every year.
there are four new findings.
the first one is about vasopressin which can help reset inner clock.
the second and third method contain two kinds of things-SK1 and CK1. they can limit the ability of light to reset the brain's clock, but the effect is not tested.
the fourth one is neurotransmitter serotonin.

【time 6】4'54''13'''
this article talks about the unusual phenomenon of Blind Cavefish which can stop its inner circadian in order to save energy.
the inner circadian is important to animals, plants, and even fungi to metabolism and so on.
experiments show that for some fish, the oxygen consumption in daytime is greater than at night when the surrounding is total dark in 24 hours.
while, for blind cavefish, the oxygen consumption in daytime is the same as at night when the surrounding is total dark in 24 hours.
the blind cavefish is not unique, but scientists do not know why.

【time 7】11'19''39'''
this article explores why we perceive time go faster and faster as time goes by.
there are several researches studying this topic. and the summary of these findings is shown as follow.
1. WJ said that people perceive time through memorable events. that is the older a person is, the more the memorable events are, the faster he perceives the time go
2.Janet's study showed that the ratio of the number of year he perceives to the age of a person. that is 2 years is 10% of a 20-year old people, but 5% of a 40-year old people. I cannot remember the relationship between of this ratio and the perceived time.
3. when a person grow older, the inner clock becomes slow.
4. old people pay less attention on time passing.
5. W&L said that stress can cause people perceive time past quickly.
in summary, there are many factors affecting people's perceive of time passing, such as age, stress and so on.