Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

14.02.2005


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:
http://www.nih.gov
http://www.nimh.nih.gov/Press/prsafetysignal.cfm

More articles from Life Sciences:

nachricht New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Novel 3-D printing technique yields high-performance composites

16.01.2018 | Materials Sciences

New application for acoustics helps estimate marine life populations

16.01.2018 | Life Sciences

Fast-tracking T cell therapies with immune-mimicking biomaterials

16.01.2018 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>