Scientists discover anti-anxiety circuit in the brain as the seat of fear

stimulation one distinct brain circuit, within a brain structure typically connected is the opposite effect with anxiety produced: their activities, replacing the trigger or increasing anxiety, brand it.

This is the finding in a paper by Stanford University School of Medicine researchers be published online March 9 in nature. The study employed Karl Deisseroth, MD, PhD, and colleagues to show that revival only in this circuit improved animals risk appetite, while there his actions they risikoscheuer renders a mouse model. This discovery could lead to new treatments for anxiety disorders, said Deisseroth, an associate professor of Bioengineering and Psychiatry and behavioral science.

The researchers could determine this particular circuit only through the cooperation with a State-of-the-art technology called Optogenetics, pioneer of Deisseroth at Stanford University, which allows scientists brain, to tease the complex circuits that make up the brain, so that they can be examined individually.

"Fear a poorly understood but common psychiatric illness," said Deisseroth, the also a practicing psychiatrist. More than one of four people in their lives experience bouts of anxiety symptoms scale sufficient permanent and intensive as adult psychiatric disorder. In addition, fear said a major factor in other major psychiatric disorders of depression, alcohol dependence, Deisseroth.

The most current anti anxiety medications work of activity in the brain circuitry, which generates fear or anxiety increases suppressed. Many of these drugs are not very effective, and those that have significant side effects such as dependency or respiratory suppression have Deisseroth said. "The discovery of a new circuit of whose action is that fear, to reduce rather than increase it, a whole strategy of the anti-anxiety treatment, could show", he added.

The anti-anxiety is ironically circuit within a structure of the brain, the amygdala, that fear is associated with long known, embedded. In General, revival in the amygdala is known to increase fear nervously. So switching the anti-anxiety would probably have been difficult, if not impossible, it look not been a new technology in which nerve cells in living animals are light-sensitive rendered so that the action in these cells of different wavelengths of light can be enabled or disabled for Optogenetics,. The technique allows researchers to certain groups of nerve cells selectively photosensitize. By providing, pulses of light through optical fibers for specific areas of the brain, scientists can not only certain nerve - cell types but also certain cell-cell connections or nervous pathways of a brain region to a different destination. The fiber optic connection is flexible and painless, so actual behavior, as well as their brain activity can be monitored animals.

On the other hand include older research approaches probe with electrodes stimulate areas of the brain nerve cell firing. But an electrode stimulates not only all the nerve cells that happen to be in the neighborhood but also fibres, only on enroute to the elsewhere are passing through. So, circuit through the fear dominant flooded increasing effects of surrounding circuit would have no effect of promoting the newly discovered anti-anxiety.

In December 2010, methods awarded the title "Method of the year" on Optogenetics of the journal nature.

In the new nature study a series of fibers of cells in a nervous "Overview" to another within the amygdala works photosensitized seems the researchers. Carefully their light-delivery positioning system, they could selectively target of this projection, so that it is enabled only if light was pulsed in the mouse brain. Doing so led behavior immediately to dramatic changes in the animals.

"The mice suddenly was much more comfortable in situations she would generally as dangerous exercise and therefore very anxious,", Deisseroth said. For example, rodents try usually wide open spaces such as to avoid, because such places exposed to leave predators. But in a standard setup simulation open and covered areas, increased the mice willingness explore the open spaces deeply, as soon as light in the novel brain circulation was pulsed. Pulse that the opposite result produces same circuit with other, inhibitory frequency of light: now more anxious was the mice. "it the test scenario squatted straight down in the relatively remote areas", said Deisseroth.

Standard laboratory measuring electrical activity confirmed in certain areas of mice of Amygdalas, that the new circuit inclination to track activation of animals of increased risk-taking.

Deisseroth said that he believes that people should be assigned as his team also results in mice. "We know that the amygdala in mice and men is similar to," he said. And just over a year ago a Stanford team under Deisseroth's Associate Director, Amit Etkin, MD, PhD, Assistant Professor of Psychiatry and behavioral science, functional imaging techniques to show that people are suffering from generalized anxiety disorder connectivity had changed from in the same regions of the brain within the amygdala, that he has involved Deisseroth of the Group Optogenetically in mice.

The study was the National Institute of mental health, the National Institute on drug abuse, the National Science Foundation, NARSAD, a Samsung scholarship and the McKnight, Woo, Snyder, and Yu funded foundations by the national institutes of health. Kay Tye, PhD, PostDoc in the Deisseroth laboratory, and Rohit Prakash, Sung-Yon Kim and Lief Fenno all students in this lab, together first authorship. Graduate other co-authors are student Logan Grosenick, undergraduate student Hosniya Zarabi, postdoc Kimberly Thompson, PhD, and research associates Viviana Gradinaru and Charu Ramakrishnan, all Deisseroth laboratory.

History source:

The above story is printed (with editorial changes by ScienceDaily staff) from materials by Stanford University Medical Center. The original article was written by Bruce Goldman.

Journal reference:

Kay M. Tye, Rohit Prakash, Sung-Yon Kim, Lief E. Fenno, Logan Grosenick, Hosniya Zarabi, Kimberly R. Thompson, Viviana Gradinaru, Charu Ramakrishnan, Karl Deisseroth. Amygdala circuit mediation reversible and bi-directional control of fear. Nature, 2011; DOI: ^ / nature09820

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