(Press-News.org) When crossing a street, we look to the left and right for cars and stay put on the sidewalk if we see a car close enough and traveling fast enough to hit us before we're able to reach the other side. It's an almost automatic decision, as though we instinctively know how to keep ourselves safe.
Now neuroscientists have found that other animals are capable of making similar instinctive safety decisions. In a study published online the week of Nov. 29 in the Proceedings of the National Academy of Sciences, University of Washington researcher Jeansok Kim demonstrates that rats weigh their odds of safely retrieving food pellets placed at varying distances from a perceived predator.
"When animals go out to forage, they're taking a risk," said Kim, a UW psychology professor. "They're leaving the safety of their nests, venturing out where there may be predators that could eat them."
But staying in the nest is not a safe option either, rats need to get out and find food. How do they decide whether it's safe to leave the nest? Kim and co-author June-Seek Choi, a visiting professor in the UW psychology department from Korea University, studied how the amygdala – known to be an important brain area for perceiving and reacting to fear – was involved in the rats' decisions to risk their safety for food.
In humans, impaired amygdala activity has been linked to risky decision-making, such as gambling. And an overactive amygdala could explain anxiety disorders, including post-traumatic stress disorder and phobias.
Kim and Choi trained male rats to retrieve a food pellet placed at varying distances from a safety zone, or nest. The rats, hungry from a restricted food supply for several days, quickly learned to retrieve the food pellets. (To see a video of rats foraging, watch "Foraging baseline day 5": http://faculty.washington.edu/jeansokk/Robogator.html).
The researchers introduced a "predator," an alligator-shaped robot that was programmed to snap its jaws and surge at the rats. With a body made of gray LEGO blocks and fangs of bright orange LEGOS, the LEGO Mindstorms Robogator was about twice the size of the rats. The researchers programmed the robot to lurch forward about 9 inches, open and shut its mouth and then return to its resting spot far away from the rats' nest.
With the robot in place, the rats began foraging as usual. When they neared the food, the Robogator quickly moved toward the rats and snapped its jaws. The rats scurried back to the safety of the nest and then momentarily froze – a typical fear response.
Still hungry, the rats paced back in forth in the nest areas, hidden from the Robogator (see video "Robot encounter day 1: Pre-amygdalar lesion": http://faculty.washington.edu/jeansokk/Robogator.html). Slowly they re-emerged and cautiously approached the food, while the Robogator continued its aggressive movements whenever the rats neared the food pellet. Most rats learned that they could safely retrieve the food pellet placed closest, 10 inches, from their nest and not intersect the robot's path. None of the rats obtained the pellet nearer the Robogator, about 30 inches from the nest.
Kim compared the rats' decision-making process to the classic math problem that asks when two trains leaving at different times from different places and traveling at different speeds will pass each other. With a predator nearby, Kim said, rats gauge how quickly they can run to the food, how quickly the predator moves and how far away the pellet is from the rat and from the predator. If they judge that there's a chance the rat and robot will cross paths, they don't attempt to get the food.
"Like when people cross the street, we just tend to automatically have a sense of what is safe," Kim said. "I think that most animals have that capability in their nervous system. Through our amygdala, we instinctively know what keeps us safe."
Overactive amygdala could explain anxiety disorders and irrational fears in humans, Kim said. Brain imaging studies show heightened amygdala activity in patients with post-traumatic stress disorder. Underactive amygdala could be linked to risk-taking and impulsive behaviors.
To study this in rats, the researchers created amygdala lesions and observed the rats' subsequent interactions with the robot. Rats with lesions were unperturbed by the Robogator, and when food was placed near the predator the rats ran straight for the food, barely flinching when the Robogator lunged and snapped (see video "Robot encounter day 2: Post-amygdalar lesion": http://faculty.washington.edu/jeansokk/Robogator.html). The same was true when the researchers inactivated the amygdala with the chemical muscimol.
When Kim and Choi increased the amygdala activity, the rats showed greater fear. Even when the food was at a safe distance from the robot, rats treated with the drug bicuculline, which increases neural activity, were too afraid to venture out for the pellet.
"Because humans share many biological and behavioral features with animals, experimental studies with rats provide valuable information toward understanding the physiological as well as the psychological aspects of fear," Kim said.
INFORMATION:
The study was funded by the National Institutes of Health, the National Research Foundation of Korea Grant, the Ministry of Education, Science and Technology and the Seoul Broadcasting System Foundation.
For more information, contact Kim at 206-616-2685 or jeansokk@uw.edu.
Neuroscience of instinct: How animals overcome fear to obtain food
2010-11-30
ELSE PRESS RELEASES FROM THIS DATE:
Motivation to end racism relies on 'yes we can' approach
2010-11-30
If you're trying to end racism, it's not enough to get people to understand that racism is still a problem. You also have to make them feel like they can do something about it, according to a new study published in Psychological Science, a journal of the Association for Psychological Science.
Tracie L. Stewart of Georgia State University was inspired to conduct the study by work she's done on evaluating a popular diversity training program. She found that the program reduced many white participants' bias in the short term, which was good. "But some white participants ...
Abnormal blood vessel function found in women with broken heart syndrome
2010-11-30
ROCHESTER, Minn. - A team of Mayo Clinic researchers has found that patients with broken heart syndrome, also known as apical ballooning syndrome (ABS), have blood vessels that don't react normally to stress. These results offer clues to the cause of this rare syndrome and may help with efforts to identify patients who are more vulnerable to mental stress so that appropriate therapies can be developed. The study is published online in the Journal of the American College of Cardiology.
Apical ballooning syndrome affects mainly postmenopausal women, and a few men. The symptoms ...
Study: Avoidance, poor coping challenge prisoners returning to society
2010-11-30
How do individuals often cope with reentry from prison to society?
Too frequently with avoidance, says Lindsay Phillips, assistant professor of psychology at Albright College in Reading, Pa. and author of the forthcoming paper, "Prison to Society: A Mixed Methods Analysis of Coping with Reentry," to be published by the International Journal of Offender Therapy and Comparative Criminology.
"There is a defined process experienced by participants, which is initial optimism about release, followed by craving substances, facing practical barriers, or feeling overwhelmed," ...
How authentic is your pomegranate juice?
2010-11-30
RIVERSIDE, Calif. – You pick up a bottle of pomegranate juice at the store because you've learned that, although it costs more than most juices, it is replete with antioxidants that bring health benefits. But wait: Is the juice you've purchased really pomegranate juice? Or is the product label you have carefully read promising more than it delivers?
A chemist at the University of California, Riverside is determined to find out. Cynthia Larive, a professor of chemistry, is playing detective by applying chemical tests to juice products sold as pomegranate juice or pomegranate ...
Evolutionary psychology: Why daughters don't call their dads
2010-11-30
CORAL GABLES, FL (December 7, 2010)— Previous research has shown that when women are in their most fertile phase they become more attracted to certain qualities such as manly faces, masculine voices and competitive abilities. A new study by University of Miami (UM) Psychologist Debra Lieberman and her collaborators offers new insight into female sexuality by showing that women also avoid certain traits when they are fertile.
The new study shows that women avoid their fathers during periods of peak fertility. The findings are included in a study entitled "Kin Affiliation ...
U of I scientists develop tool to trace metabolism of cancer-fighting tomato compounds
2010-11-30
URBANA – The University of Illinois scientists who linked eating tomatoes with a reduced risk of prostate cancer have developed a tool that will help them trace the metabolism of tomato carotenoids in the human body. And they've secured funding from the National Institutes of Health to do it.
"Scientists believe that carotenoids—the pigments that give the red, yellow, and orange colors to some fruits and vegetables—provide the cancer-preventive benefits in tomatoes, but we don't know exactly how it happens," said John W. Erdman, a U of I professor of human nutrition.
The ...
Moderate alcohol consumption lowers the risk of metabolic diseases
2010-11-30
With the emergence of an epidemic of obesity and type 2 diabetes (DM) throughout the world, the association of lifestyle habits that may affect the risk of metabolic diseases is especially important. Most prospective studies have shown that moderate drinkers tend to have about 30% lower risk of developing late onset diabetes than do non-drinkers, and moderate drinkers also tend to be at lower risk of developing metabolic syndrome (MS). A cross-sectional analysis of 6172 subjects age 35 -75 in Switzerland related varying levels of alcohol intake to the presence of DM, ...
Contact with dads drops when women ovulate
2010-11-30
Through an innovative use of cell phone records, researchers at UCLA, the University of Miami and Cal State, Fullerton, have found that women appear to avoid contact with their fathers during ovulation.
"Women call their dads less frequently on these high-fertility days and they hang up with them sooner if their dads initiate a call," said Martie Haselton, a UCLA associate professor of communication in whose lab the research was conducted.
Because they did not have access to the content of the calls, the researchers are not able to say for sure why ovulating women ...
Duke scientists look deeper for coal ash hazards
2010-11-30
DURHAM, N.C. – As the U.S. Environmental Protection Agency weighs whether to define coal ash as hazardous waste, a Duke University study identifies new monitoring protocols and insights that can help investigators more accurately measure and predict the ecological impacts of coal ash contaminants.
"The take-away lesson is we need to change how and where we look for coal ash contaminants," says Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment. "Risks to water quality and aquatic life don't end with surface water contamination, ...
Marsupial embryo jumps ahead in development
2010-11-30
DURHAM, N.C. – Long a staple of nature documentaries, the somewhat bizarre development of a grub-like pink marsupial embryo outside the mother's womb is curious in another way.
Duke University researchers have found that the developmental program executed by the marsupial embryo runs in a different order than the program executed by virtually every other vertebrate animal.
"The limbs are at a different place in the entire timeline," said Anna Keyte, a postdoctoral biology researcher at Duke who did this work as part of her doctoral dissertation. "They begin development ...