The findings, published in the Journal of Neuroscience, could help lead to the development of effective behavioral and pharmacological therapies to treat anxiety disorders, such as post-traumatic stress disorder, phobias and panic attacks.
There are two main stages of sleep – REM and non-REM – and both are necessary to maintain health and to regulate multiple memory systems, including emotional memory. During non-REM sleep, the body repairs tissue, regenerates cells and improves the function of the body's immune system. During REM sleep, the brain becomes more active and the muscles of the body become paralyzed. Additionally, dreaming generally occurs during REM sleep, as well as physiological events including saccadic eye movements and rapid fluctuations of respiration, heart rate and body temperature. One particular physiological event, which is a hallmark sign of REM sleep, is the appearance of phasic pontine waves (P-waves). The P-wave is a unique brain wave generated by the activation of a group of glutamatergic cells in a specific region within the brainstem called the pons.
Memories of fearful experiences can lead to enduring alterations in emotion and behavior and sleep plays a natural emotional regulatory role after stressful and traumatic events. Persistence of sleep disturbances, particularly of REM sleep, is predictive of developing symptoms of anxiety disorders. A core symptom of these disorders frequently reported by patients is the persistence of fear-provoking memories that they are unable to extinguish. Presently, exposure therapy, which involves controlled re-exposure to the original fearful experience, is considered one of the most effective evidence-based treatments for anxiety disorders. Exposure therapy produces a new memory, called an extinction memory, to coexist and compete with the fearful memory when the fearful cue/context is re-encountered.
The strength of the extinction memory determines the efficacy of exposure therapy. A demonstrated prerequisite for the successful development of an extinction memory is adequate sleep, particularly REM sleep, after exposure therapy. However, adequate or increased sleep alone does not universally guarantee its therapeutic efficacy.
"Given the inconsistency and unpredictability of exposure therapy, we are working to identify which process(es) during REM sleep dictate the success or failure of exposure therapy," said Subimal Datta, PhD, director and principle investigator at the Laboratory of Sleep and Cognitive Neuroscience at BUSM who served as the study's lead author.
The researchers used contextual fear extinction training, which works to turn off the conditioned fear, to study which brain mechanisms play a role in the success of exposure therapy. The study results showed that fear extinction training increased REM sleep. Surprisingly, however, only 57 percent of subjects retained fear extinction memory, meaning that they did not experience the fear, after 24 hours. There was a tremendous increase of phasic P-wave activity among those subjects. In 43 percent of subjects, however, the wave activity was absent and they failed to retain fear extinction memory, meaning that they re-experienced fear.
"The study results provide direct evidence that the activation of phasic P-wave activity within the brainstem, in conjunction with exposure therapy, is critical for the development of long-term retention of fear extinction memory," said Datta, who also is a professor of psychiatry and neurology at BUSM. In addition, the study indicates the important role that the brainstem plays in regulating emotional memory.
Future research will explore how to activate this mechanism in order to help facilitate the development of new potential pharmacological treatments that will complement exposure therapy to better treat anxiety and other psychological disorders.
According to the National Institute of Mental Health, anxiety disorders affect approximately 40 million American adults each year. While anxiety can sometimes be a normal and beneficial reaction to stress, some people experience excessive anxiety that they are unable to control, which can negatively impact their day to day life.
Research included in this study was supported in part by the National Institutes of Health's National Institute of Mental Health under grant award number MH 59839 (PI: Datta) and the National Institute of Neurological Disorders and Stroke under grant award number NS 34004 (PI: Datta).
Gina DiGravio | Source: EurekAlert!
Further information: www.bmc.org
Further Reports about: anxiety disorder > brain mechanism > BUSM > exposure therapy > eye movement > health services > mental disorders > Neuroscience > P-wave > REM sleep > sleep disturbance > traumatic event
More articles from Studies and Analyses:
Skin Cancer May Be Linked to Lower Risk of Alzheimer’s Disease
16.05.2013 | American Academy of Neurology
Long-term outcomes in patients with advanced coronary artery disease are better than expected
16.05.2013 | Minneapolis Heart Institute Foundation
Researchers have shown that, by using global positioning systems (GPS) to measure ground deformation caused by a large underwater earthquake, they can provide accurate warning of the resulting tsunami in just a few minutes after the earthquake onset.
For the devastating Japan 2011 event, the team reveals that the analysis of the GPS data and issue of a detailed tsunami alert would have taken no more than three minutes. The results are published on 17 May in Natural Hazards and Earth System Sciences, an open access journal of ...
A new study of glaciers worldwide using observations from two NASA satellites has helped resolve differences in estimates of how fast glaciers are disappearing and contributing to sea level rise.
The new research found glaciers outside of the Greenland and Antarctic ice sheets, repositories of 1 percent of all land ice, lost an average of 571 trillion pounds (259 trillion kilograms) of mass every year during the six-year study period, making the oceans rise 0.03 inches (0.7 mm) per year. ...
About 99% of the world’s land ice is stored in the huge ice sheets of Antarctica and Greenland, while only 1% is contained in glaciers.
However, the meltwater of glaciers contributed almost as much to the rise in sea level in the period 2003 to 2009 as the two ice sheets: about one third. This is one of the results of an international study with the involvement of geographers from the University of Zurich.
Second sound is a quantum mechanical phenomenon, which has been observed only in superfluid helium.
Physicists from the University of Innsbruck, Austria, in collaboration with colleagues from the University of Trento, Italy, have now proven the propagation of such a temperature wave in a quantum gas. The scientists have published their historic findings in the journal Nature.
Below a critical temperature, certain fluids become superfluid ...
Researchers use synthetic silicate to stimulate stem cells into bone cells
In new research published online May 13, 2013 in Advanced Materials, researchers from Brigham and Women's Hospital (BWH) are the first to report that synthetic silicate nanoplatelets (also known as layered clay) can induce stem cells to become bone cells without the need of additional bone-inducing factors.
Synthetic silicates are made ...
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News