• Gryphon Login
  • MyCourses
  • Alumni
  • UCLA Health
  • Contact Us
Prospective Students

Prospective Students

Prospective Students
  • Admissions
    Procedure & Timelines
    • Admissions Timeline
    • Admissions Procedure
    • Basis of Selection
    • COVID-19 Impacts on Admissions
    • Housing Information
    • Interview Process
    • Prerequisites
    General Information
    • Statement of Diversity
    • Mission Statement
    • Curriculum Resdesign
    • Honor Code
    • FAQs
    • Admissions Brochure
    • Admissions Timeline
    • Admission Procedure
    • Basis of Selection
    • Competencies
    • COVID-19 Impact on Admissions
    • DACA Applicants
    • DGSOM Mission Statement
    • FAQs
    • Honor Code
    • Housing Information
    • Interview Process
    • Statement of Diversity
    • Virtual Events
  • Outreach & Pipeline Programs
    Summer Pre-Health and Postbaccaluareate Programs
    • UCLA SHPEP
    • UCLA PREP
    • UCLA RAP
    Outreach and Recruitment
    • Conferences and Events
    • Stay Connected!
    • Contact Us
    • Conferences & Outreach Events
    • Summer Pre-Health and Postbaccalaureate Programs
    • Contact Us
    • Stay Connected
  • Financial Aid & Scholarships
  • Degrees & Programs
  • Curriculum
  • Student Life
    Why Choose UCLA
    • Research
    • Clinical Work
    • Service Opportunities
    • Global Health Impact
    • Why You'll Love LA
    Campus Life
    • Student Organizations
    • Annual Events
    • Day in the Life
    • Around Campus
    • Photo Galleries
    • Medical and Research News
    • Medical Student Council
    • Geffy Guide
    • Search Campus and Health News
    • Service Opportunities
    • Global Health Impact
    • Why You'll Love LA
    • Photo Galleries
    • Day in the Life
    • Around Campus
    • Medical and Research News
    • Search Campus and Health News
  • How to Apply
  • Gryphon Login
  • MyCourses
  • Alumni
  • UCLA Health
  • Contact Us

Prospective Students

Search Campus and Health News

Search Campus and Health News

Search Campus and Health News

  • Health News
  • A Day in the Life
  • Around Campus
  • Medical and Research News
  • Health News
  • A Day in the Life
  • Around Campus
  • Medical and Research News
  1. Home
  2. Prospective Students
  3. Student Life
  4. Search Campus and Health News

Search Campus and Health News

Share this

Health News

Title

UCLA and Stanford researchers pinpoint origin of sighing reflex in the brain

Health News

Date
02/08/2016
Article

 

“You must remember this: a kiss is just a kiss, a sigh is just a sigh.”

Contrary to the words immortalized by the piano singer in “Casablanca,” a sigh is far more than a sigh. Heaving an unconscious sigh is a life-sustaining reflex that helps preserve lung function.

Now a new study by researchers at UCLA and Stanford has pinpointed two tiny clusters of neurons in the brain stem that are responsible for transforming normal breaths into sighs. Published in the Feb. 8 advance online edition of Nature, the discovery may one day allow physicians to treat patients who cannot breathe deeply on their own — or who suffer from disorders in which frequent sighing becomes debilitating.

“Sighing appears to be regulated by the fewest number of neurons we have seen linked to a fundamental human behavior,” explained Jack Feldman, a professor of neurobiology at the David Geffen School of Medicine at UCLA and a member of the UCLA Brain Research Institute. “One of the holy grails in neuroscience is figuring out how the brain controls behavior. Our finding gives us insights into mechanisms that may underlie much more complex behaviors.”

According to Mark Krasnow, a professor of biochemistry and Howard Hughes Medical Institute Investigator at the Stanford University School of Medicine, the new findings shed light on the network of cells in the brain stem that generates breathing rhythm.

Sighing regions of the brain stem
Krasnow lab/Stanford
On each side of the brain stem, a florescent-green marker illuminates the two networks of 200 neurons that control the sighing reflex.

“Unlike a pacemaker that regulates only how fast we breathe, the brain’s breathing center also controls the type of breath we take,” Krasnow said. “It’s made up of small numbers of different kinds of neurons. Each functions like a button that turns on a different type of breath. One button programs regular breaths, another sighs, and the others could be for yawns, sniffs, coughs and maybe even laughs and cries.”

Using a mouse model, Krasnow and his colleagues screened more than 19,000 gene-expression patterns in the animals’ brain cells. They found roughly 200 neurons in the brain stem that manufacture and release one of two neuropeptides, which enable brain cells to talk to each other. Still, the scientists did not know which brain cells these neurons communicated with or why.

Conversely, Feldman knew that the same family of peptides, also found in humans, was highly active in a part of the brain that influences breathing and plays an important role in sighing. What he had not identified were the genes or neurons that controlled them.

By joining forces, Krasnow’s and Feldman’s labs discovered that the peptides excited a second set of 200 neurons. These cells increased the rate that they activated the mouse’s breathing muscles to produce a sigh, from roughly 40 times an hour to more than 400 times per hour.

The researchers found that blocking one of the peptides cut the animals’ sighing rate in half. Silencing both peptides halted the mice’s ability to sigh completely.

“These molecular pathways are critical regulators of sighing, and define the core of a sigh-control circuit,” Krasnow said. “It may now be possible to find drugs that target these pathways to control sighing.”

Sighing is vital to lung function, and thus to life, Feldman emphasized.

“A sigh is a deep breath, but not a voluntary deep breath,” he said. “It starts out as a normal breath, but before you exhale, you take a second breath on top of it.”

On average, a person sighs every five minutes, which translates into 12 sighs per hour.

The purpose of sighing is to inflate the alveoli, the half-billion, tiny, delicate, balloon-like sacs in the lungs where oxygen enters and carbon dioxide leaves the bloodstream. Sometimes individual sacs collapse, though.

“When alveoli collapse, they compromise the ability of the lung to exchange oxygen and carbon dioxide,” Feldman said. “The only way to pop them open again is to sigh, which brings in twice the volume of a normal breath. If you don’t sigh, your lungs will fail over time.”

Turning on sighing would be useful in people who cannot breathe deeply on their own. Early artificial breathing devices did not regularly give patients a deep breath, and many patients died. Current ventilators regularly deliver a large inflation of air that mimics a sigh.

“If you don’t sigh every five minutes of so, the alveoli will slowly collapse, causing lung failure,” Feldman said. “That’s why patients in early iron lungs had such problems, because they never sighed.”

The ability to limit the sighing reflex could prove useful in anxiety disorders and other psychiatric conditions where sighing grows debilitating.

The mechanism behind the emotional roots of conscious sighing remains a mystery.

“There is certainly a component of sighing that relates to an emotional state. When you are stressed, for example, you sigh more,” Feldman said. “It may be that neurons in the brain areas that process emotion are triggering the release of the sigh neuropeptides — but we don’t know that.”

The research was supported by the Howard Hughes Medical Institute, National Institutes of Health grants HL70029, HL40959 and NS72211, a Walter V. and Idun Berry postdoctoral fellowship, the NIH Medical Scientist Training Program, and Canadian Institutes of Health Research and Alberta Innovates Health Solutions postdoctoral fellowships.

Like Us on Facebook Follow Us on Twitter Subscribe to Our Videos on YouTube Follow us on Instagram Connect with Us on LinkedIn Follow us on Pinterest Follow us on Flickr Follow us on Sharecare
Top 10 U.S. Medical Schools
  • Giving
  • Publications
  • Newsroom
  • Weekly Digest
  • Directory
  • Contact Us
  • Diversity
  • Emergency
  • Maps & Directions
  • UC Regents
  • Abuse Free
  • Volunteer
  • Biomed Library
  • Disability Resources
  • UCLA Health
  • Smoke-Free
  • Sitemap
  • Terms of Use
Top 10 U.S. Medical Schools
Like Us on Facebook Follow Us on Twitter Subscribe to Our Videos on YouTube Follow us on Instagram Connect with Us on LinkedIn Follow us on Pinterest Follow us on Flickr Follow us on Sharecare