Penn Comprehensive Neuroscience Center

Faculty Members
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David M. Raizen, MD, PhD

Assistant Professor of Neurology
Center for Sleep and Circadian Neurobiology, University of Pennsylvania School of Medicine
Department: Neurology

Contact information
Dept Neurology
462 Stemmler Hall
415 Curie Blvd
Philadelphia, PA 19104-4283
Graduate Group Affiliations
Education:
BA (Biochemistry)
University of Texas at Austin, 1989.
PhD (Neuroscience)
University of Texas Southwestern, 1997.
MD (Medicine)
University of Texas Southwestern, 1997.
Post-Graduate Training
Intern in Medicine, Hospital of the University of Pennsylvania, 1998-1999.
Resident in Neurology, Hospital of the University of Pennsylvania, 1999-2002.
Fellow in Sleep Medicine, University of Pennsylvania School of Medicine, 2002-2004.
Certifications
American Board of Psychiatry and Neurology (Recertified 2013), 2003.
American Board of Sleep Medicine, 2005.
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Description of Research Expertise

Research Interests
The regulation and function of sleep

Key Words: sleep, ecdysis, molting, behavior, amyloid, neuropeptides

Description of Research
Quiescent behavioral states are universal to the animal world with the most famous and mysterious of these being sleep. Despite the fact that we spend one third of our life sleeping, and despite the fact that all animals appear to sleep, the core function of sleep remains a mystery. In addition, the molecular basis underlying sleep/wake regulation is poorly understood.

We use C. elegans as a model system to address these questions. C. elegans offers many experimental advantages including powerful genetic tools as well as a simple neuroanatomy.

Growth of C. elegans from an embryo to an adult is punctuated by four molts, during which the animal secretes a new cuticle and sheds its old one. Prior to each molt the worm has a quiescent behavioral state called lethargus. Lethargus has several similarities to sleep including rapid reversibility to strong stimulation, increased sensory arousal threshold, and homeostasis, which is manifested by an increased depth of sleep following a period of deprivation. Similarity to sleep at the molecular genetic level is demonstrated by the identification of signaling pathways that regulate C. elegans lethargus in the similar fashion to their regulation of sleep in mammals and arthropods. For examples, cAMP signaling promotes wakefulness and epidermal growth factor signaling promotes sleep in C. elegans and other organisms. We have identified new regulators of sleep like behavior in C. elegans and are currently studying how these regulators function to regulate sleep.

By studying the purpose and genetic regulation of nematode lethargus, we hope to identify additional novel sleep regulators, and to gain insight into why sleep and sleep-like states had evolved, a central biological mystery.

Rotation projects
Please see David about possible projects.

Description of Clinical Expertise

Sleep disorders: In particular disorders of sleep regulation and restless leg syndrome.

Selected Publications

Yu CC, Raizen DM, Fang-Yen C: Multi-well imaging of development and behavior in Caenorhabditis elegans. Journal of Neuroscience Methods 223: 35-39, February 2014.

Nagy S, Raizen* DM, Biron D. *Corresponding Author: Measurements of behavioral quiescence in Caenorhabditis elegans. Methods Epub ahead of print, 2014.

Driver RJ, Lamb AL, Wyner AJ, and Raizen DM : DAF-16/FOXO Regulates Homeostasis of Essential Sleep-like Behavior during Larval Transitions in C. elegans. Current Biology 23(6): 501-506, March 2013.

Nelson MD, Trojanowski NF, George-Raizen JB, Smith CJ, Yu C-C, Fang-Yen C, and Raizen DM: The neuropeptide NLP-22 regulates a sleep-like state in Caenorhabditis elegans Nature Communications 4: 2846, 2013.

Belfer SJ,Chuang HS, Freedman BL, Yuan J, Norton M, Bau HH, and Raizen DM: Caenorhabditis-in-Drop array for monitoring C. elegans quiescent behavior. Sleep in press, 2013.

Dabbish NS, Raizen DM.: GABAergic synaptic plasticity during a developmentally regulated sleep-like state in C. elegans. Journal of Neuroscience 31(44): 15932-15943, Nov 2011.

Chuang HS, Raizen DM, Dabbish N, Bau HH.: Electro-worming: The behaviors of Caenorhabditis (C.) elegans in DC and AC electric fields. Physics of Fluids 23(9): 91107-911071, September 2011.

Chuang HS, Raizen DM, Lamb A, Dabbish N, Bau HH.: Dielectrophoresis of Caenorhabditis elegans. Lab on Chip 11(4): 599-604, Feb 2011.

Zimmerman JE, Raizen DM, Maycock MH, Maislin G, Pack AI.: A video method to study Drosophila sleep. Sleep 31(11): 1587-1598, November 2008.

David M. Raizen, John E. Zimmerman, Matthew H. Maycock, Uyen D. Ta, Young-jai You, Meera V. Sundaram & Allan I. Pack: Lethargus is a Caenorhabditis elegans sleep-like state. Nature 451, January 2008.

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Last updated: 07/15/2014
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