“That edge sounds good. It sounds adaptive. It sounds like perception is enhanced and that it can keep you safe in the face of danger,” says Alexander Shackman, a researcher at the University of Wisconsin-Madison.
But it sounds like there’s also a catch, one that Shackman and his coauthors — including Richard Davidson, UW-Madison psychology and psychiatry professor — described in the Jan. 19 Journal of Neuroscience.
“It makes us more sensitive to our external surroundings as a way of learning where or what a threat may be, but interferes with our ability to do more complex thinking,” Davidson says.
Faced with the possibility of receiving an unpleasant electric shock, the study’s subjects showed enhanced activity in brain circuits responsible for taking in visual information, but a muted signal in circuitry responsible for evaluating that information. Remove the threat of shock (and thus the stress and anxiety) and the effect is reversed: less power for vigilance, more power for strategic decision-making.
The shift in electrical activity in the brain, captured by a dense mesh of sensors placed on the scalp, may be the first biological description of a paradox in experimental psychology.
It has long been known that imminent danger can enhance the ability to detect faint stimuli in the environment, such as the crackle of a leaf signaling the approach of a predator. But it is equally clear that the stress and anxiety aroused by a threat can profoundly disrupt the ability to think clearly and perform more complex “executive” tasks.
“In the last few years, theorists have hypothesized that this paradox might reflect several systems working in conjunction: one responsible for the rapid detection of external stimuli, the other responsible for the slower, more reflective evaluation of that incoming information,” Shackman says. “Stress upsets the balance of those systems.”
In fact, as the senses go into overdrive, they are probably confounding the rest of the brain all the more.
“Your ability to do more complex tasks is disrupted just as the amount of information you’re receiving through your eyes and ears is enhanced,” Shackman says. “You’re having trouble focusing on the information coming in, but your brain is taking in more and more potentially irrelevant information. You can have a viscous feedback loop, a sort of double-whammy effect.”
The resulting confusion favors quick, reflexive actions, the “survival instincts” often mentioned by trauma survivors — Noise? RUN! — in a way that was likely adaptive in the dangerous environments in which the ancestors to modern humans evolved.
“In our evolutionary past, the dangers we faced were really survival-threatening,” Davidson says. “That’s not so much the case now. Because of the nature of our brains, we can use our neural capacity to create our own internal danger. We can worry about the future and ruminate about the past.”
Either one is likely to present a real hurdle to effective decision-making under stress.
“This is part of a growing body of evidence showing that stress does have important consequences for the brain, not just something that arouses the body — tension in your muscles or butterflies in the stomach,” says Davidson, who studies the effects of meditation as director of UW-Madison’s Center for Investigating Healthy minds.
“One of the things we would expect is that if we use an antidote like systematic meditation training to learn to control stress it would not just calm the body, but improve our ability to engage in complex analytical activity,” he says.
Jeffrey S. Maxwell of the U.S. Army Research Laboratory joined Shackman as lead author of the study, which was funded by the Department of Defense, National Institutes for Health and National Science Foundation.
Chris Barncard | Newswise Science News
Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth
Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena
Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers
Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...
Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.
At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
26.07.2017 | Event News
21.07.2017 | Event News
19.07.2017 | Event News
26.07.2017 | Physics and Astronomy
26.07.2017 | Life Sciences
26.07.2017 | Earth Sciences