Posts tagged heart rate
Articles and news from the latest research reports.
2-D or 3-D? That is the Question
The increased visual realism of 3-D films is believed to offer viewers a more vivid and lifelike experience—more thrilling and intense than 2-D because it more closely approximates real life. However, psychology researchers at the University of Utah, among those who use film clips routinely in the lab to study patients’ emotional conditions, have found that there is no significant difference between the two formats. The results were published recently in PLOS ONE.
The study aimed to validate the effectiveness of 3-D film, a newer technology, as compared to 2-D film that is currently widely used as a research tool. Film clips are used in psychological and neuroscience studies as a standardized method for assessing emotional development. Because it is less invasive than other methods, it is especially useful when studying the emotional responses of young people for whom emotional well-being is critical to healthy development.
Author Sheila Crowell, assistant professor of psychology at the U, says that results of the large and tightly controlled study also suggest that as an entertainment medium, 3-D may not provide a different experience from 2-D, insofar as evoking emotional responses go.
“We set out to learn whether technological advances like 3-D enhance the study of emotion, especially for young patients who are routinely exposed to high-tech devices and mediums in their daily lives,” says Crowell. “Both 2-D and 3-D are equally effective at eliciting emotional responses, which also may mean that the expense involved in producing 3-D films is not creating much more than novelty. Further studies are of course warranted, but our findings should be encouraging to researchers who cannot now afford 3-D technologies.”
How the study was conducted
Researchers looked at several measures of emotional state in 408 subjects, including palm sweat, breathing and cardiovascular responses, such as heart rate. These measures are commonly used to gauge emotional responses.
Four film clips were chosen because each prompted one discrete emotion intensely and in context without viewing the entire film. Study participants viewed a 3-D and 2-D clip of approximately five minutes of each film: “My Bloody Valentine” (fear), “Despicable Me” (amusement), “Tangled” (sadness) and “The Polar Express” (thrill or excitement). Participants were randomized to view the films in a design that balanced the pairs of films watched, in which format, and order of presentation. The complex configurations allowed the researchers to compare not only emotional responses, but effects of format and viewing order on the results.
Taken as a whole, the results showed few significant differences between physiological reactions to the films. When accounting for the large number of statistical tests, only one difference was seen between the formats—the number of electrodermal responses (palm sweat) during a thrilling scene from “The Polar Express” 3-D clip. The researchers believe that could be because the 3-D content of the film is of especially high quality, with more and a larger variety of 3-D effects than the others.
Supporting the overall finding is that participants’ individual differences in anxiety, inability to control emotional responses or “thrill seeking” did not alter the psychological or physiological responses to 3-D viewing. In other words, personality differences did not change the results: 2-D is still equally effective for emotion elicitation. According to Crowell, “this could be good news for people who would rather not wear 3-D glasses or pay the extra money to see these types of films.”
'Tickling' your ear could be good for your heart
Stimulating nerves in your ear could improve the health of your heart, researchers have discovered.
A team at the University of Leeds used a standard TENS machine like those designed to relieve labour pains to apply electrical pulses to the tragus, the small raised flap at the front of the ear immediately in front of the ear canal.
The stimulation changed the influence of the nervous system on the heart by reducing the nervous signals that can drive failing hearts too hard.
Professor Jim Deuchars, Professor of Systems Neuroscience in the University of Leeds’ Faculty of Biological Sciences, said: “You feel a bit of a tickling sensation in your ear when the TENS machine is on, but it is painless. It is early days—so far we have been testing this on healthy subjects—but we think it does have potential to improve the health of the heart and might even become part of the treatment for heart failure.”
The researchers applied electrodes to the ears of 34 healthy people and switched on the TENS (Transcutaneous electrical nerve stimulation) machines for 15-minute sessions. They monitored the variability of subjects’ heartbeats and the activity of the part of the nervous system that drives the heart. Monitoring continued for 15 minutes after the TENS machine was switched off.
Lead researcher Dr Jennifer Clancy, of the University of Leeds’ School of Biomedical Sciences, said: “The first positive effect we observed was increased variability in subjects’ heartbeats. A healthy heart does not beat like a metronome. It is continually interacting with its environment—getting a little bit faster or a bit slower depending on the demands on it. An unhealthy heart is more like a machine constantly banging out the same beat. We found that when you stimulate this nerve you get about a 20% increase in heart rate variability.”
The second positive effect was in suppressing the sympathetic nervous system, which drives heart activity using adrenaline.
Dr Clancy said: “We measured the nerve activity directly and found that it reduced by about 50% when we stimulated the ear. This is important because if you have heart disease or heart failure, you tend to have increased sympathetic activity. This drives your heart to work hard, constricts your arteries and causes damage. A lot of treatments for heart failure try to stop that sympathetic activity—beta-blockers, for instance, block the action of the hormones that implement these signals. Using the TENS, we saw a reduction of the nervous activity itself.”
The researchers found significant residual effects, with neither heart rate variability or sympathetic nerve activity returning to the baseline 15 minutes after the TENS machine had been switched off.
The technique works by stimulating a major nerve called the vagus, which has an important role in regulating vital organs such as the heart. There is a sensory branch of the vagus in the outer ear and, by sending electrical current down the nerves and into the brain, researchers were able to influence outflows from the brain that regulate the heart. Vagal nerve stimulation has previously been used to treat conditions including epilepsy.
Professor Deuchars said: “We now need to understand how big and how lasting the residual effect on the heart is and whether this can help patients with heart problems, probably alongside their usual treatments. The next stage will be to conduct a pre-clinical study in heart failure patients.”
(Source: eurekalert.org)
Researcher Discovers the Mechanisms That Link Brain Alertness and Increased Heart Rate
George Washington University (GW) researcher David Mendelowitz, Ph.D., was recently published in the Journal of Neuroscience for his research on how heart rate increases in response to alertness in the brain. Specifically, Mendelowitz looked at the interactions between neurons that fire upon increased attention and anxiety and neurons that control heart rate to discover the “why,” “how,” and “where to next” behind this phenomenon.
“This study examines how changes in alertness and focus increase your heart rate,” said Mendelowitz, vice chair and professor of pharmacology and physiology at the GW School of Medicine and Health Sciences. “If you need to focus on a new task at hand, or suddenly need to become more alert, your heart rate increases. We sought to understand the mechanisms of how that happens.”
While the association between vigilance and increased heart rate is long accepted, the neurobiological link had not yet been identified. In this study, Mendelowitz found that locus coeruleus (LC) noradrenergic neurons — neurons critical in generating alertness — directly influence brainstem parasympathetic cardiac vagal neurons (CVNs) — neurons responsible for controlling heart rate. LC noradrenergic neurons were shown to inhibit the brainstem CVNs that generate parasympathetic activity to the heart. The receptors activated within this pathway may be targets for new drug therapies to promote slower heart rates during heightened states.
“Our results have important implications for how we may treat certain conditions in the future, such as post-traumatic stress disorder, chronic anxiety, or even stress,” said Mendelowitz. “Understanding how these events alter the cardiovascular system gives us clues on how we may target these pathways in the future.”
(Source: smhs.gwu.edu)
When Choirs Sing, Many Hearts Beat As One
Lifting voices together in praise can be a transcendent experience, unifying a congregation in a way that is somehow both fervent and soothing. But is there actually a physical basis for those feelings?
To find this out, researchers of the Sahlgrenska Academy at the University of Gothenburg in Sweden studied the heart rates of high school choir members as they joined their voices. Their findings, published this week in Frontiers in Neuroscience, confirm that choir music has calming effects on the heart — especially when sung in unison.
Using pulse monitors attached to the singers’ ears, the researchers measured the changes in the choir members’ heart rates as they navigated the intricate harmonies of a Swedish hymn. When the choir began to sing, their heart rates slowed down.
"When you sing the phrases, it is a form of guided breathing," says musicologist Bjorn Vickhoff of the Sahlgrenska Academy who led the project. "You exhale on the phrases and breathe in between the phrases. When you exhale, the heart slows down."
But what really struck him was that it took almost no time at all for the singers’ heart rates to become synchronized. The readout from the pulse monitors starts as a jumble of jagged lines, but quickly becomes a series of uniform peaks. The heart rates fall into a shared rhythm guided by the song’s tempo.
"The members of the choir are synchronizing externally with the melody and the rhythm, and now we see it has an internal counterpart," Vickhoff says.
This is just one little study, and these findings might not apply to other singers. But all religions and cultures have some ritual of song, and it’s tempting to ask what this could mean about shared musical experience and communal spirituality.
"It’s a beautiful way to feel. You are not alone but with others who feel the same way," Vickhoff says.
He plans to continue exploring the physical and neurological responses of our body to music on a long-term project he calls Body Score. As an instructor, he wonders how this knowledge might be used to create more cohesive group dynamic in a classroom setting or in the workplace.
"When I was young, every day started with a teacher sitting down at an old organ to sing a hymn," Vickhoff says. "Wasn’t that a good idea — to get the class to think, ‘We are one, and we are going to work together today.’ "
Perhaps hymns aren’t for everyone, but we want to know, what songs soothe your heart? For a bit of inspiration, we’ve included a clip of the Mormon Tabernacle Choir, whose members know a lot about singing together.
Researchers look to breath to identify stress
According to a new pilot study, published in IOP Publishing’s Journal of Breath Research, there are six markers in the breath that could be candidates for use as indicators of stress.
The researchers hope that findings such as these could lead to a quick, simple and non-invasive test for measuring stress; however, the study, which involved just 22 subjects, would need to be scaled-up to include more people, over a wider range of ages and in more “normal” settings, before any concrete conclusions can be made, they state.
Lead-author of the study, Professor Paul Thomas, said: “If we can measure stress objectively in a non-invasive way, then it may benefit patients and vulnerable people in long-term care who find it difficult to disclose stress responses to their carers, such as those suffering from Alzheimer’s.”
The study, undertaken by researchers at Loughborough University and Imperial College London, involved 22 young adults (10 male and 12 female) who each took part in two sessions: in the first, they were asked to sit comfortably and listen to non-stressful music; in the second, they were asked to perform a common mental arithmetic test that has been designed to induce stress.
A breath test was taken before and after each session, whilst heart-rates and blood pressures were recorded throughout. The breath samples were examined using a technique known as gas chromatography-mass spectrometry, and then statistically analysed and compared to a library of compounds.
Two compounds in the breath – 2-methyl, pentadecane and indole – increased following the stress exercise which, if confirmed, the researchers believe could form the basis of a rapid test.
A further four compounds were shown to decrease with stress, which could be due to changes in breathing patterns.
“What is clear from this study is that we were not able to discount stress. It seems sensible and prudent to test this work with more people over a range of ages in more normal settings.
“We will need to think carefully about experimental design in order to explore this potential relationship further as there are ethical issues to consider when deliberately placing volunteers under stress. Any follow up study would need to be led by experts in stress,” Professor Thomas continued.
Breath profiling has become an attractive diagnostic method for clinicians, and recently researchers have found biomarkers associated with tuberculosis, multiple cancers, pulmonary disease and asthma. It is still unclear how to best manage external factors, such as diet, environment and exercise, which can affect a person’s breath sample.
“It is possible that stress markers in the breath could mask or confound other key compounds that are used to diagnose a certain disease or condition, so it is important that these are accounted for,” said Professor Thomas.
The researcher’s initial assumptions are that stressed people breathe faster and have increased pulse rates and an elevated blood-pressure, which is likely to change their breath profile. They emphasise, however, that it is too soon to postulate the biological origins and the roles of the compounds as part of a stress-sensitive response.