Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Rat brain’s executive hub quells alarm center if stress is controllable


Treatments for mood and anxiety disorders are thought to work, in part, by helping patients control the stresses in their lives. A new study in rats by National Institutes of Health (NIH) grantees provides insight into the brain mechanisms likely involved. When it deems a stressor controllable, an executive hub in the front of the brain quells an alarm center deep in the brainstem, preventing the adverse behavioral and physiological effects of uncontrollable stress.

"It’s as if the prefrontal cortex says: ’Cool it, brainstem! We have control over this and there is no need to get so excited’," quipped Steven Maier, Ph.D., University of Colorado, whose study was funded by the National Institute of Mental Health (NIMH) and the National Institute on Drug Abuse (NIDA). Maier and colleagues posted their findings online in Nature Neuroscience, February 6, 2005.

Lack of control over stressful life experiences has been implicated in mood and anxiety disorders. Rats exposed to uncontrollable stress develop learned helplessness, a syndrome similar to depression and post traumatic stress disorder (PTSD). They lose the ability to learn how to escape stressors. Activation of a brainstem area (dorsal raphe nucleus) has been implicated in such reactions. But this area is too small and lacks the proper sensory inputs to judge whether a stressor is controllable. Many of its inputs come conspicuously from the mid-prefrontal cortex area (medial prefrontal cortex), seat of higher order functions, such as problem-solving and learning from experience. These signals are sent via the chemical messenger serotonin, which is involved in mood regulation and in mediating the effects of the most widely prescribed antidepressants. The medial prefrontal cortex has also been implicated as the source of an "all clear" signal that quells fear in rats.*

To find out the role of the medial prefrontal cortex, Maier’s team chemically inactivated it in rats that were learning to control a stressor. The animals showed the same brainstem activation and, eventually, the same behaviors characteristic of depression (failure to learn to escape) and anxiety (exaggerated fear conditioning) as rats exposed to uncontrollable stress.

"If an organism can cope behaviorally with an event, there’s no need for intense physiological adaptation. It has been assumed that when stressors are uncontrollable the organism learns this, and that it is this uncontrollability that sets off the neural cascade," explained Maier. "However, our data suggest that instead it is control that is the active ingredient. If the organism has control and can cope behaviorally, this is detected by the cortex, which then sends inhibitory signals to the brainstem."

In PTSD, which is triggered by uncontrollable stress, medial prefrontal cortex activity is reduced. Proposing an analogous mechanism, Maier speculated that loss of inhibition from the medial prefrontal cortex may explain increased activity of the amygdala (a fear hub) in PTSD.

Also participating the study were: Drs. Jose Amat, Erin Paul, Sondra Bland, Linda Watkins, and Michael Baratta.

Amat J, Baratta MV, Paul E, Bland ST, Watkins LR, Maier SF. Medial prefrontal cortex determines how stressor controllability affects behavior and dorsal raphe nucleus. Nat Neurosci. 2005 Feb 06; [Epub ahead of print].

Jules Asher | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Gene therapy shows promise for treating Niemann-Pick disease type C1
27.10.2016 | NIH/National Human Genome Research Institute

nachricht 'Neighbor maps' reveal the genome's 3-D shape
27.10.2016 | International School of Advanced Studies (SISSA)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

How nanoscience will improve our health and lives in the coming years

27.10.2016 | Materials Sciences

OU-led team discovers rare, newborn tri-star system using ALMA

27.10.2016 | Physics and Astronomy

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

More VideoLinks >>>