• UCLA Health
  • myUCLAhealth
  • School of Medicine
U Magazine

U Magazine

U Magazine
  • Home
  • Current Issue
  • Centennial Campaign for UCLA Issue
  • Browse U Magazine
  • Letters to the Editor
  • Subscribe
  • Contact
  • UCLA Health
  • myUCLAhealth
  • School of Medicine

U Magazine

Browse U Magazine

  1. Home
  2. Browse U Magazine
Share this
The Cutting Edge

The Wakeful Brain

The Wakeful Brain- MedMag-S2012BRIGHT LIGHT AROUSES and makes it easier to stay awake. Very bright light not only arouses us, but is known to have anti-depressant effects. Conversely, dark rooms can make us sleepy. It's the reason some people use masks to make sure light doesn't wake them while they sleep.

Now, researchers at UCLA have identified the group of neurons that mediates whether light arouses us — or not. Jerome Siegel, Ph.D., professor of psychiatry at the Jane and Terry Semel Institute for Neuroscience and Human Behavior at UCLA, and colleagues report in the online edition of the Journal of Neuroscience that the cells necessary for a light-induced arousal response are located in the hypothalamus. It is an area at the base of the brain responsible for, among other things, control of the autonomic nervous system, body temperature, hunger, thirst, fatigue — and sleep.

These cells release a neurotransmitter called hypocretin, Dr. Siegel says. The researchers compared mice with and without hypocretin and found that those who didn't have it were unable to stay awake in the light, while those who had it showed intense activation of these cells in the light but not while they were awake in the dark.

"This current finding explains prior work in humans that found that narcoleptics lack the arousing response to light, unlike other equally sleepy individuals, and that both narcoleptics and Parkinson's patients have an increased tendency to be depressed compared to others with chronic illnesses," says Dr. Siegel.

Prior studies of the behavioral role of hypocretin in rodents had examined the neurotransmitter's function during only light phases (normal sleep time for mice) or dark phases (their normal wake time) but not both. And the studies only examined the rodents when they were performing a single task.

In the current study, researchers examined the behavioral capabilities of mice that had their hypocretin genetically "knocked out" (KO mice) and compared them with the activities of normal, wild-type mice (WT) that still had their hypocretin neurons. The researchers tested the two groups while they performed a variety of tasks during both light and dark phases.

Surprisingly, they found that the KO mice were only deficient at working for positive rewards during the light phase. During the dark phase, however, these mice learned at the same rate as their WT littermates and were completely unimpaired in working for the same rewards.

Consistent with the data in the KO mice, the activity of hypocretin neurons in their WT littermates was maximized when working for positive rewards during the light phase, but the cells were not activated when performing the same tasks in the dark phase.


Previous
Tracking Teen Suicide
Next
David T. Feinberg, M.D., M.B.A


YOU ARE VIEWING

Winter/Spring 2012

Winter/Spring 2012
E-Brochure
Printable PDF
IN THIS ISSUE
  • The Invisible Backbone
  • Detecting Pancreatic Cancer in Saliva
  • Visualizing the Web of Depression
  • The Rhythm of Learning
  • UCLA in the Community
  • Fish Oil Lowers Prostate Risk
  • Older May Not Be Better
  • Heartfelt Award
  • Turning Stem Cells into Cancer-Killing Warriors
  • Tracking Teen Suicide
  • The Wakeful Brain
  • David T. Feinberg, M.D., M.B.A
  • Five-Star Care
  • A New Face for an Old Friend
  • Therapeutic Aesthetic
  • Culture of Caring
  • The Music of Medicine
  • Awards/Honors
  • Grants
  • Alumni Celebrate Life of Former Dean of Students
  • One-on-One: Jamie D. Feusner, M.D. ’99
  • Postcard from The Hood
  • MAA 2012 Reunion Weekend
  • MAA on the Road
  • Honoring the Visionaries in Our Community
  • Chairs of Distinction
  • Gifts
  • In Memoriam
  • Gift from the Heart
  • Events
  • A Vision Realized
  • The Healing Medicine of a Wet Nose
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
UCLA Health hospitals ranked best hospitals by U.S. News & World Report
  • UCLA Health
  • Find a Doctor
  • School of Medicine
  • School of Nursing
  • UCLA Campus
  • Directory
  • Newsroom
  • Subscribe
  • Patient Stories
  • Giving
  • Careers
  • Volunteer
  • International Services
  • Privacy Practices
  • Nondiscrimination
  • Billing
  • Health Plans
  • Emergency
  • Report Broken Links
  • Terms of Use
  • 1-310-825-2631
  • Maps & Directions
  • Contact Us
  • Your Feedback
  • Report Misconduct
  • Get Social
  • Sitemap
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

Sign in to myUCLAhealth

Learn more about myUCLAhealth