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(Anatomy) Sweat: Scent of Fear Impacts Cognitive Performance

 
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adedios
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PostPosted: Sat Apr 01, 2006 8:38 am    Post subject: (Anatomy) Sweat: Scent of Fear Impacts Cognitive Performance Reply with quote






Rice University
1 April 2006

Scent of fear impacts cognitive performance

Rice University study finds greater accuracy and more cautious behavior on tests
The chemical warning signals produced by fear improve cognitive performance, according to a study at Rice University in Houston.
Women who were exposed to chemicals from fear-induced sweat performed more accurately on word-association tasks than did women exposed to chemicals from other types of sweat or no sweat at all. The study was published this month in the journal Chemical Senses.

"It is well-documented in the research literature that animals experiencing stress and fear produce chemical warning signals that can lead to behavioral, endocrinological and immunological changes in their fellow animals of the same species, but we wanted to see if this applies to humans as well," said principal investigator Denise Chen, assistant professor of psychology at Rice.

For the study, Chen collected samples of sweat from research volunteers who kept gauze pads in their armpits while they watched videos of horror movies and nonthreatening documentaries. The sweat samples were then stored in a freezer until needed for the study.

Next, Chen had 75 female students between the ages of 18 and 22 respond to 320 pairs of words that flashed for three seconds each on a computer screen. For each pair, the participants had to press a key to indicate whether the words were associated with each other (for example, arms and legs) or not (arms and wind). Some of the words were associated with threatening or fear-related topics, like weapons.

Each participant had a piece of gauze attached above their lips so that they were exposed to either chemicals from sweat or none at all during the tests. Chen compared how the chemicals from sweat impacted the speed and accuracy of participants' results on the word-association tests.

When processing meaningfully related word pairs, the participants exposed to the fear chemicals were 85 percent accurate, and those in either the neutral sweat or the control (no-sweat) condition were 80 percent accurate. "The subjects in the fear condition were six percent more accurate, which is a statistically significant difference," Chen said.

When processing word pairs that were ambiguous in threat content, such as one neutral word paired with a threatening word or a pair of neutral words, subjects in the fear condition were 15 to 16 percent slower in responding than those in the neutral sweat condition, and this difference was statistically significant. Chen's theory is that the chemicals from fear-induced sweat prompted subjects to be more cautious.

The research participants were not aware of the nature of the smells, and the smells did not differ on the intensity or pleasantness ratings.

"We demonstrated that in humans, chemical signals from fear facilitated overall accuracy in identifying word relatedness independent of the perceived qualities of the smells," Chen said. "The effect may arise from a learned association, including greater cautiousness and changes in cognitive strategies."

"Human olfaction is a young, vibrant field," Chen said, noting that the behavioral study of this subject is still in the early stage. "Olfactory receptors were discovered in the early 1990s. We now know that olfaction involves hundreds of receptors."

Results like these from Chen's behavioral research and studies from other labs form an integral part of a multipronged approach to the understanding of human olfaction.

Coauthors of Chen's study included former Rice undergraduate students Ameeta Katdare and Nadia Lucas, a Rice Century Scholar.


###
Chen's research was funded by the National Institutes of Health.

*************************************************************

Questions to explore further this topic:

An anatomy of the skin

http://www.wounds1.com/News/MainStory.cfm/13
http://www.anatomyatlases.org/.....on07.shtml

What is sweat?

http://kidshealth.org/kid/talk/yucky/sweat.html
http://www.nlm.nih.gov/medline.....003218.htm
http://www.cnn.com/HEALTH/library/DS/00305.html
http://www.beathyperhidrosis.c.....-works.htm
http://www.embarrassingproblems.com/sweating.htm

What are skin glands?

http://distance.stcc.edu/aandp...../skin2.htm

What are sweat glands?

http://sprojects.mmi.mcgill.ca...../sweat.htm
http://www.aad.org/professiona.....Glands.htm

Eccrine Sweat Glands
http://www.sweating.ca/eccrine_sweat_glands.html

Apocrine Sweat Glands
http://www.sweating.ca/apocrine_sweat_glands.html

Can emotions affect sweating?

http://kidshealth.org/teen/que.....sweat.html

What are antiperspirants?

http://www.fda.gov/fdac/featur.....sweat.html

What are heat rashes?

http://www.nlm.nih.gov/medline.....001966.htm

What is Hyperhidrosis?

http://www.sweathelp.org/Engli.....nition.asp
http://www.nlm.nih.gov/medline.....007259.htm
http://dwb.unl.edu/Teacher/NSF...../what.html

What is Hidradenitis?

http://www.mayoclinic.com/heal.....is/HQ00837

Sweaty palms

http://www.sweaty-palms.com/sweaty_palms.html

A review on the endocrine system

http://kidshealth.org/parent/g.....crine.html

What is fear?

http://www.science.ie/content/.....ion_id=672

Can animals really smell fear?

http://zebra.sc.edu/smell/ann/myth5.html

GAMES

http://school.discovery.com/le.....heet4.html


Last edited by adedios on Sat Jan 27, 2007 4:34 pm; edited 2 times in total
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PostPosted: Tue Oct 31, 2006 8:17 am    Post subject: Why We Love to be Scared Reply with quote

Why We Love to be Scared

By Charles Q. Choi
Special to LiveScience
posted: 30 October 2006
06:06 pm ET

For all of their stomach-turning gore, horror films and haunted houses attract people in droves. This ability of the human brain to turn fear on its head could be a key to treating phobias and anxiety disorders, according to scientists.

When people get scared, their bodies automatically triggers the "fight or flight" response—their heart rates increase, they breathe faster, their muscles tense, and their attention focuses for quick and effective responses to threats.

"It's nature's way of protecting us," said clinical psychologist David Rudd at Texas Tech University.

For the full article:

http://www.livescience.com/hum.....actor.html
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PostPosted: Wed Jan 24, 2007 9:43 am    Post subject: Be afraid, be very afraid, if you learned to Reply with quote

Society for Neuroscience
23 January 2007

Be afraid, be very afraid, if you learned to

Study on fear responses suggests new understanding of anxiety disorders
WASHINGTON, DC January 23, 2007 – A new study on rats has identified a part of the brain's cortex that controls learned but not innate fear responses.

The results suggest that hyperactivity in a region of the prefrontal cortex might contribute to disorders of learned fear in humans, such as post-traumatic stress disorder and other anxiety disorders, say authors Kevin A. Corcoran, PhD, and Gregory Quirk, PhD, of the Ponce School of Medicine in Puerto Rico. Their report appears in the January 24 issue of The Journal of Neuroscience.

While building on previous findings, this study contradicts prior thinking that the amygdala, which plays a central role in emotional learning, is sufficient for processing and expressing fear, and it opens the potential for new avenues of treatment, the researchers say.

"This is the first paper demonstrating that a region of the cortex is involved in learned fear but not in innate fear," says Markus Fendt, PhD, of the Novartis Institutes for Biomedical Research in Basel, Switzerland, who is not connected with the study.

In their study, Corcoran and Quirk taught rats to associate a 30-second tone with a shock to the foot at the end of the tone. Upon hearing the same tone the next day, rats spent nearly 70 percent of the time of the tone frozen, a typical fear response.

In another group of rats, the researchers chemically blocked activity in the prelimbic cortex, which is located near the front of the brain and close to the midline between the two hemispheres. These rats spent only 14 percent of the time freezing to the sound of the tone.

Yet the rats' innate, or natural, fears seemed unaffected by blocking the prelimbic cortex; they froze as much in response to seeing a cat or being placed in a large open area as they did to hearing the tone. Furthermore, when the team trained rats with the tone after chemically inactivating the prelimbic cortex, and then tested them drug-free the next day, the rats showed a normal fear response, indicating that inactivating the prelimbic cortex did not prevent them from learning to fear the tone.

The prelimbic cortex is connected to the amygdala, and, based on their findings, Corcoran and Quirk speculate that "by modulating amygdala activity, the prelimbic cortex is important for determining the circumstances in which it is appropriate to convey learned fears." In contrast, they propose that fear responses to innate threats are automatic and do not require cortical involvement.

"Corcoran and Quirk's work raises the question of whether learned fear is more controllable--for example, by higher brain functions--than innate fear," says Fendt.


###
The work was supported with grants from the National Institutes of Health.

The Journal of Neuroscience is published by the Society for Neuroscience, an organization of more than 36,500 basic scientists and clinicians who study the brain and nervous system. Corcoran can be reached at kevincorcoran@gmail.com.
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PostPosted: Wed Feb 07, 2007 10:30 am    Post subject: Male sweat boosts women's hormone levels Reply with quote

Male sweat boosts women's hormone levels

By Robert Sanders, Media Relations | 06 February 2007

BERKELEY – Just a few whiffs of a chemical found in male sweat is enough to raise levels of the stress hormone cortisol in heterosexual women, according to a new study by University of California, Berkeley, scientists.

The study, reported this week in The Journal of Neuroscience, provides the first direct evidence that humans, like rats, moths and butterflies, secrete a scent that affects the physiology of the opposite sex.

"This is the first time anyone has demonstrated that a change in women's hormonal levels is induced by sniffing an identified compound of male sweat," as opposed to applying a chemical to the upper lip, said study leader Claire Wyart, a post-doctoral fellow at UC Berkeley.

The team's work was inspired by previous studies by Wyart's colleague Noam Sobel, associate professor of psychology at UC Berkeley and director of the Berkeley Olfactory Research Program. He found that the chemical androstadienone - a compound found in male sweat and an additive in perfumes and colognes - changed mood, sexual arousal, physiological arousal and brain activation in women.

Yet, contrary to perfume company advertisements, there is no hard evidence that humans respond to the smell of androstadienone or any other chemical in a subliminal or instinctual way similar to the way many mammals and even insects respond to pheromones, Wyart said. Though some humans exhibit a small patch inside their nose resembling the vomeronasal organ in rats that detects pheromones, it appears to be vestigial, with no nerve connection to the brain.

"Pheromones are chemical molecules expressed by a species aimed at other members of the species to induce stereotyped behavior or hormonal changes," Wyart explained. "Many people argue that human pheromones don't exist, because humans don't exhibit stereotyped behavior. Nonetheless, this male chemical signal, androstadienone, does cause hormonal as well as physiological and psychological changes in women. More cognitive studies need to be done to understand how androstadienone affects female cognitive functions."

One implication of the finding is that there may be better ways to raise cortisol levels in patients with diseases such as Addison's disease, which is characterized by low cortisol. Instead of giving the hormone in pill form, which has side effects such as ulcers and weight gain, "a potential therapeutic mechanism whereby merely smelling synthesized or purified human chemosignals may be used to modify endocrine balance," the authors wrote.

Sweat has been the main focus of research on human pheromones, and in fact, male underarm sweat has been shown to improve women's moods and affect their secretion of luteinizing hormone, which is normally involved in stimulating ovulation. Other studies have shown that when female sweat is applied to the upper lip of other women, these women respond by shifting their menstrual cycles toward synchrony with the cycle of the woman from whom the sweat was obtained.

Androstadienone, a derivative of testosterone that is found in high concentration in male sweat, and in all other body secretions, has garnered the most attention. However, though its effect on a woman's mood, physiological arousal and brain activity suggests that the chemical is a possible pheromone-like signal in humans, its effect on hormone levels was unknown.

Wyart and Sobel set out to test whether androstadienone affects hormone levels as well, focusing on the hormone cortisol. Cortisol is secreted by the body in times of stress, priming the body for "fight or flight."

In two trials, a total of 48 undergraduate women at UC Berkeley were asked to take 20 sniffs from a bottle containing androstadienone, which smells vaguely musky. Over a period of two hours, the volunteers provided five saliva samples from which cortisol levels were determined.

Compared to their response when sniffing a control odor (yeast), the women who sniffed androstadienone reported an improved mood and significantly higher sexual arousal, while their physiological response, including blood pressure, heart rate and breathing, also increased. This was consistent with previous studies.

In addition, however, the UC Berkeley researchers found that cortisol levels rose within about 15 minutes of sniffing androstadienone, and remained elevated for more than an hour.

Wyart noted that, though this is the first time a specific component of male sweat has been shown to affect women's hormones, other constituents of male sweat likely have a similar effect. The question remains: Which comes first - the change in cortisol level, which may induce a change in mood or arousal; or a mood change that increases cortisol levels?

"We next need to look at other hormones that could explain the diversity of effects of androstadienone on sexual arousal and mood," she said.

Coauthors of the report include UC Berkeley undergraduates Sarah Wilson, Jonathan Chen and Andrew McClary; senior scientist Rehan Khan; and Dr. Wallace Webster, an otolaryngology resident at Kaiser Permanente Hospital in Oakland, Calif. The work was sponsored by the National Institute on Deafness and Other Communicable Disorders of the National Institutes of Health, and by the Army Office of Research.
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PostPosted: Tue Mar 20, 2007 10:15 am    Post subject: Brain Can Learn Fear By Seeing Others’ Fears Reply with quote

Brain Can Learn Fear By Seeing Others’ Fears

By Andrea Thompson
LiveScience Staff Writer
posted: 20 March 2007
09:36 am ET

Whether you get stung by a bee or simply watch as a friend gets stung, you might start to run and hide every time a bee buzzes across your path. A new study reveals why you do this: It turns out the brain areas that respond when fear is learned through personal experience are also triggered when we see someone else afraid.

The finding, detailed in the March issue of the journal Social Cognitive and Affective Neuroscience, could explain why some people are afraid of things like spiders and snakes despite little contact with them.

For the full article:

http://www.livescience.com/hum.....rning.html
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PostPosted: Mon Apr 02, 2007 8:03 pm    Post subject: Bizarre Human Brain Parasite Precisely Alters Fear Reply with quote

Bizarre Human Brain Parasite Precisely Alters Fear

By Charles Q. Choi
Special to LiveScience
posted: 02 April 2007
05:02 pm ET

Rats usually have an innate fear of cat urine. The fear extends to rodents that have never seen a feline and those generations removed from ever meeting a cat. After they get infected with the brain parasite Toxoplasma gondii, however, rats become attracted to cat pee, increasing the chance they'll become cat food.

This much researchers knew. But a new study shows the parasite, which also infects more half the world's human population, seems to target a rat's fear of cat urine with almost surgical precision, leaving other kinds of fear alone.

This discovery could shed light "on how fear is generated in the first place" and how people can potentially better manage phobias, researcher Ajai Vyas, a Stanford University neuroscientist, told LiveScience.

For the full article:

http://www.livescience.com/ani.....urine.html
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PostPosted: Mon May 07, 2007 7:19 am    Post subject: Why Do You Stink? Reply with quote

Why Do You Stink?
By Ben Mauk

posted: 04 May 2007 04:15 pm ET

Don't get offended! You could be hyper-hygienic and you'd still ooze odors. Even grosser, bacteria's to blame.

It starts in the sweat glands, which are coiled tubes unique to mammals that release fluids from the blood supply of the dermis layer of skin. Apocrine sweat glands, found in select locations such as the scalp, nipples, genitals and armpits, secrete the viscous substances that invite bacterial growth. (Actual sweat is produced by eccrine glands, which are distributed widely over the body.) The bacteria break down your waste secretions, and it's these hard-working guests that create your special funk.

For the full article:

http://www.livescience.com/mys.....stink.html
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PostPosted: Sat Dec 29, 2007 9:21 am    Post subject: Brain Turns to Positive Thoughts When Faced With Death Reply with quote

Brain Turns to Positive Thoughts When Faced With Death
By E.J. Mundell, HealthDay Reporter

posted: 28 December 2007 03:28 pm ET

(HealthDay News) -- When thoughts of death intrude, the human mind isn't paralyzed with negativity or fear. Instead, the brain instinctively moves toward happier notions and images, a new study suggests.

The finding supports the notion that people are stronger, emotionally, when faced with their own or a loved one's death than they may have ever thought possible.

For the full article:

http://www.livescience.com/healthday/610943.html
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