New understandings of circadian rhythms
July 13, 2011
Science Daily/NIH/National Institute of General Medical Sciences
A tiny plant called Arabidopsis thaliana just helped scientists unearth new clues about the daily cycles of many organisms, including humans. This is the latest in a long line of research, much of it supported by the National Institutes of Health, that uses plants to solve puzzles in human health.
While other model organisms may seem to have more in common with us, greens like Arabidopsis provide an important view into genetics, cell division and especially light sensing, which drives 24-hour behavioral cycles called circadian rhythms.
Some human cells, including cancer cells, divide with a 24-hour rhythm. One of the main human circadian rhythm genes, cryptochrome, has been associated with diabetes and depression. Both of these discoveries grew from work with plants.
Scientists aren't yet certain why night is the best time for stems to grow, but Kay speculates it has to do with using resources efficiently. Plants pick up carbon and nitrogen during the day, then store these essential nutrients as starch and proteins. "In the later night, they can release these resources in a coordinated fashion to provide the building blocks for stem growth," says Kay. "Our understanding of human health and the role of clocks in health and disease can greatly benefit from studying how clocks work in plants," he adds.
How plants like Arabidopsis suppress harmful genes may also help improve HIV therapies. A team of biologists led by Craig Pikaard at Washington University in St. Louis is investigating RNA polymerases, chemicals important in determining which genes get switched on, to learn how plants silence harmful virus-derived genes. Similar silencing pathways could be harnessed for HIV therapies.
http://www.sciencedaily.com/releases/2011/07/110713131642.htm
Stress and alcohol 'feed' each other
July 19, 2011
Science Daily/Alcoholism: Clinical & Experimental Research
Acute stress is thought to precipitate alcohol drinking. Yet the ways that acute stress can increase alcohol consumption are unclear. A new study investigated whether different phases of response to an acute stressor can alter the subjective effects of alcohol. Findings indicate bi-directional relationships between alcohol and stress.
"Anecdotal reports suggest that alcohol dampens the physiological or negative emotional effects of stress but this has been hard to demonstrate in the lab," said Emma Childs, research associate at The University of Chicago and corresponding author for the study. "Another way that stress could increase drinking is by altering alcohol's effects. For example, if stress reduces the intoxicating effects of alcohol, individuals may drink more alcohol to produce the same effect.
Childs explained that the body's reaction to stress involves separate physiological and emotional consequences that occur at different times after the stress. "For example," she said, "the increase in heart rate and blood pressure, the release of cortisol, and also the increased feelings of tension and negative mood each reach a climax and dissipate at a different rate. Therefore, drinking more alcohol might have different effects, depending on how long after the stress a person drinks."
"The results demonstrated bi-directional relationships between alcohol and stress," said Childs. "Alcohol can change the way that the body deals with stress: it can decrease the hormone cortisol which the body releases to respond to stress, and it can prolong the feelings of tension produced by the stress. Stress can also change how alcohol makes a person feel: it can reduce the pleasant effects of alcohol or increase craving for more alcohol."
Childs added that it is often hard to separate alcohol's effects upon stress reactions from its effects on the perception of how stressful an experience is. "However, in our study we administered alcohol after the stressful experience, then examined the effects of alcohol on stress responses so ruling out any effect of alcohol upon perception of the stress. We showed that alcohol decreases the hormonal response to the stress, but also extends the negative subjective experience of the event. We also showed that stress decreased the pleasant effects of the alcohol. These findings illustrate a complex bi-directional interactions between stress and alcohol."
In summary, said Childs, using alcohol to cope with stress may actually make a person's response to stress worse, and prolong recovery from a stressor. "Stress may also alter the way that alcohol makes us feel in a way that increases the likelihood of drinking more alcohol," she said. "Stress responses are beneficial in that they help us to react to adverse events. By altering the way that our bodies deal with stress, we may be increasing the risks of developing stress-related diseases, not the least of which is alcohol addiction."
http://www.sciencedaily.com/releases/2011/07/110715163216.htm
New evidence of age-related decline in the brain's master circadian clock
July 25, 2011
Science Daily/University of California - Los Angeles
A new study of the brain's master circadian clock reveals that a key pattern of rhythmic neural activity begins to decline by middle age. The study may have implications for the enormous number of older people who have difficulty sleeping and adjusting to time changes.
"Aging has a profound effect on circadian timing," said Block, a professor of psychiatry and biobehavioral sciences and of physiological science. "It is very clear that animals' circadian systems begin to deteriorate as they age, and humans have enormous problems with the quality of their sleep as they age, difficulty adjusting to time-zone changes and difficulty performing shift-work, as well as less alertness when awake. There is a real change in the sleep-wake cycle.
"The question is, what changes in the nervous system underlie all of that? This paper suggests a primary cause of at least some of these changes is a reduction in the amplitude of the rhythmic signals from the SCN." The SCN, located in the hypothalamus, is the central circadian clock in humans and other mammals and controls not only the timing of the sleep-wake cycle but also many other rhythmic and non-rhythmic processes in the body.
"With many neurological disorders, patients have a hard time sleeping during the night and staying awake during the day," said Colwell, who was a postdoctoral fellow in Block's lab in the early 1990s at the University of Virginia. "One of the main clinical complaints of patients with Huntington's disease and Parkinson's disease is they cannot sleep and do not respond well to sleeping pills. We think the same dysfunction we see with normal aging occurs much earlier and more severely with these patients, and we hope that the treatment strategies we develop for aging can be applied to help patients with neurodegenerative diseases as well. If we learn what is going wrong, then we may be able to develop treatments."
http://www.sciencedaily.com/releases/2011/07/110719093808.htm
Music reduces anxiety in cancer patients
August 10, 2011
Science Daily/Wiley-Blackwell
Cancer patients may benefit from sessions with trained music therapists or from listening to music. A new systematic review shows using music can reduce anxiety in cancer patients, and may also have positive effects on mood, pain and quality of life.
"The evidence suggests that music interventions may be useful as a complementary treatment to people with cancer," said lead researcher Joke Bradt of the Department of Creative Arts Therapies at Drexel University in Philadelphia, US. "Music interventions provided by trained music therapists as well as listening to pre-recorded music both have shown positive outcomes in this review, but at this time there is not enough evidence to determine if one intervention is more effective than the other."
http://www.sciencedaily.com/releases/2011/08/110809212424.htm
Increased light may moderate fearful reactions
August 12, 2011
Science Daily/University of Virginia
Biologists and psychologists know that light affects mood, but a new study indicates that light may also play a role in modulating fear and anxiety.
"We looked at the effect of light on learned fear, because light is a pervasive feature of the environment that has profound effects on behavior and physiology," said Wiltgen, an assistant professor of psychology and an expert on learning. "Light plays an important role in modulating heart rate, circadian rhythms, sleep/wake cycles, digestion, hormones, mood and other processes of the body. In our study we wanted to see how it affects learned fear."
"The implications of this in humans is this: that being diurnal, the absence of light can be a source of fear," Wiltgen said. "But increased light can be used to reduce fear and anxiety and to treat depression. If we can come to understand the cellular mechanisms that affect this, then eventually abnormal anxiety and fear might be treated with improved pharmaceuticals to mimic or augment light therapy."
http://www.sciencedaily.com/releases/2011/08/110810153707.htm
Brain waves control the impact of noise on sleep
September 6, 2011
Science Daily/University of Liège
During sleep, our perception of the environment decreases. However the extent to which the human brain responds to surrounding noises during sleep remains unclear. Researchers have now used brain imaging to study responses to sounds during sleep. They show that brain activity in the face of noise is controlled by specific brain waves during sleep. Researchers found that perception of the environment is not continuously reduced during sleep, but rather varies throughout sleep under the influence of particular brain waves.
They show that brain activity in the face of noise is controlled by specific brain waves during sleep. In particular, waves called sleep 'spindles' prevent the transmission of sounds to auditory brain regions. Conversely, when sounds are associated with brain waves called 'K-complexes', activation of auditory areas is larger. Our perception of the environment is therefore not continuously reduced during sleep, but rather varies throughout sleep under the influence of particular brain waves.
Conversely, sounds can induce the production during sleep of brain waves called 'K-complexes'. The results brought by this new study demonstrate that production of K-complexes by sounds is associated with a larger activation of auditory brain areas. While spindles prevent the transmission of sounds, K-complexes reflect a more important transmission of sounds to the sleeping brain.
The effects of noise on sleep are therefore controlled by specific brain waves. In particular, the human brain is isolated from the environment during sleep spindles, which might allow essential sleep functions to operate such as the consolidation of memory for previously acquired information. These brain waves thus play a crucial role in sleep quality and stability in the face of noise.
http://www.sciencedaily.com/releases/2011/09/110906121014.htm
Sleep disorders affect 40 percent of Canadians
September 8, 2011
Science Daily/Université Laval
Sleep disorders affect 40% of adult Canadians according to a study conducted by Université Laval researchers under the supervision of Dr. Charles M. Morin. The work of Dr. Morin and his colleagues will be presented at the 4th World Congress on Sleep Medicine which runs September 10-14 in Quebec City, Canada.
Although many respondents experienced at least one symptom of insomnia, only 13% said they had consulted a healthcare professional about it. The survey data revealed that Canadians use prescription medicine (10%), natural products (9%), over-the-counter drugs (7%), or alcohol (5%) to treat their sleep problems.
Surprisingly, the researchers observed that 9.5% of French speakers suffered from insomnia compared to 14.3% of English speakers. However, French speakers take more prescribed sedatives (13% vs. 9%) and natural products (16% vs. 7%) than English-speaking Canadians.
"Many people who suffer from insomnia try to treat the problem themselves rather than consulting a healthcare professional," said Dr. Morin, a professor and researcher at Université Laval's School of Psychology. "This is not a good idea because we don't know the risks and benefits of products that have not been approved by government health agencies," he explained.
http://www.sciencedaily.com/releases/2011/09/110908104005.htm
Brain study reveals stress code
October 9, 2011
Science Daily/University of Leicester
Neuroscientists investigating the 'brain code' claim to have made a significant step forwards in understanding how the brain deals with stress- and mitigates its impact.
Examining what they term 'thin' and 'mushroom-like' parts of nerve cells in the brain, which are responsible for learning and remembering, they discovered that it is possible to alter what is remembered -- thereby mitigating the stress of painful memories.
A team from the University of Leicester has identified a particular protein that the brain produces in response to stress. Tests on mice revealed that those without this protein were less 'outgoing' and preferred to 'hide in the dark'.
"We have identified a protein that the brain produces in response to stress in order to reduce the number of mushroom spines and therefore reduce future anxiety associated with stressful events. This protein, lipocalin-2, is normally not produced, but its fabrication dramatically increases in response to stress in the hippocampus. When we added lipocalin-2 to neurons in culture the way it occurs on stress, neurons started losing their "memory spines" -- the mature, mushroom-shaped ones.
"Thus, the brain produces lipocalin-2 in order to protect us from "too much anxiety" and help us cope with various adverse life events. "Identification of lipocalin-2 as a new player the brain uses to help us cope with stress is an important step forward. We are getting closer to deciphering molecular mechanisms of stress that, if not functioning properly, may lead to stress-related psychiatric diseases."
"Stress-related psychological and mental disturbances are extremely common and affect more than 30% of the population. We are keen to investigate whether the mechanisms discovered by us apply to humans and could help inform clinical strategies to deal with anxiety disorders and depression."
http://www.sciencedaily.com/releases/2011/10/111003151826.htm
High to moderate levels of stress lead to higher mortality rate
October 21, 2011
Science Daily/Oregon State University
A new study concludes that men who experience persistently moderate or high levels of stressful life events over a number of years have a 50 percent higher mortality rate. In general, the researchers found only a few protective factors against these higher levels of stress -- people who self-reported that they had good health tended to live longer and married men also fared better. Moderate drinkers also lived longer than non-drinkers.
In general, the researchers found only a few protective factors against these higher levels of stress -- people who self-reported that they had good health tended to live longer and married men also fared better. Moderate drinkers also lived longer than non-drinkers.
"Being a teetotaler and a smoker were risk factors for mortality," said Carolyn Aldwin, lead author of the study and a professor of human development and family sciences at Oregon State University. "So perhaps trying to keep your major stress events to a minimum, being married and having a glass of wine every night is the secret to a long life."
This is the first study to show a direct link between stress trajectories and mortality in an aging population. Unlike previous studies that were conducted in a relatively short term with smaller sample sizes, this study was modified to document major stressors -- such as death of a spouse or a putting a parent into a retirement home -- that specifically affect middle-aged and older people.
Those in the low-stress group experienced an average of two or fewer major life events in a year, compared with an average of three for the moderate group and up to six for the high stress group. One of the study's most surprising findings was that the mortality risk was similar for the moderate versus high stress group.
"It seems there is a threshold and perhaps with anything more than two major life events a year and people just max out," Aldwin said. "We were surprised the effect was not linear and that the moderate group had a similar risk of death to the high-risk group."
http://www.sciencedaily.com/releases/2011/10/111020122441.htm
Evidence for the existence of a hypnotic state? Key may be in the glazed staring eyes
October 25, 2011
Science Daily/Suomen Akatemia (Academy of Finland)
A multidisciplinary group of researchers from Finland and Sweden has found that the strange stare of patients under hypnosis may be a key that can eventually lead to a solution to a long debate about the existence of a hypnotic state
One of the most widely known features of a hypnotized person in the popular culture is a glazed, wide-open look in the eyes. Paradoxically, this sign has not been considered to have any major importance among researchers and has never been studied in any detail, probably due to the fact that it can be seen in only some hypnotized people.
Published in the online journal PLoS ONE, the study was done with a very highly hypnotizable participant who can be hypnotized and dehypnotized by just using a one-word cue. The change between hypnotic state and normal state can thus be varied in seconds.
The researchers used high-resolution eye-tracking methodology and presented a set of well-established oculomotor tasks that trigger automatic eye behavior. They found the glazed stare was accompanied by objectively measurable changes in automatic, reflexive eye behavior that could not be imitated by non-hypnotized participants.
In the field of hypnosis research this result means that hypnosis can no longer be regarded as mental imagery that takes place during a totally normal waking state of consciousness. On the other hand, the result may have wider consequences for psychology and cognitive neuroscience, since it provides the first evidence of the existence of a conscious state in humans that has previously not been scientifically confirmed.
Hypnosis has had a long and controversial history in psychology, psychiatry and neurology. For over 100 years researchers have debated if a special hypnotic state exists or whether it is just about using cognitive strategies and mental imagery in a normal waking state. So far, a hypnotic state has never been convincingly demonstrated, and therefore, many researchers regard the hypnotic state to be just a popular myth in psychology.
http://www.sciencedaily.com/releases/2011/10/111025091559.htm
Dreams activate the brain in a similar way to real actions
October 28, 2011
Science Daily/Max-Planck-Gesellschaft
The ability to dream is a fascinating aspect of the human mind. However, how the images and emotions that we experience so intensively when we dream form in our heads remains a mystery. Up to now it has not been possible to measure dream content. Scientists in Germany have now succeeded, for the first time, in analyzing the activity of the brain during dreaming.
They were able to do this with the help of lucid dreamers, i.e. people who become aware of their dreaming state and are able to alter the content of their dreams. The scientists measured that the brain activity during the dreamed motion matched the one observed during a real executed movement in a state of wakefulness.
The coincidence of the brain activity measured during dreaming and the conscious action shows that dream content can be measured. "With this combination of sleep EEGs, imaging methods and lucid dreamers, we can measure not only simple movements during sleep but also the activity patterns in the brain during visual dream perceptions," says Martin Dresler, a researcher at the Max Planck Institute for Psychiatry.
http://www.sciencedaily.com/releases/2011/10/111028113626.htm