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Date of Award


Access Type

Campus Access

Document type


Degree Name

Doctor of Philosophy (PhD)

Degree Program

Neuroscience & Behavior

First Advisor

Eric L. Bittman

Second Advisor

Geert J. de Vries

Third Advisor

William J. Schwartz

Subject Categories

Neuroscience and Neurobiology


The suprachiasmatic nucleus of the hypothalamus (SCN) contains a master pacemaker that controls a wide variety of circadian rhythms of physiology and behavior. Recent work has provided a thorough understanding of the molecular mechanisms by which these oscillations are generated. The rhythmic expression of clock genes is essential to pacemaker function. These clock genes are also expressed rhythmically throughout the mammalian organism including peripheral organs and brain regions outside of the SCN. Synchronization within these tissues and maintenance of phase angle between the different systems depends upon the integrity of the SCN. The present experiments will focus on the nature of the SCN-dependent signals responsible for the entrainment of peripheral oscillations. Such signals may be neural, humoral, or behavioral, and various organs may rely on different signals or a combination of such signals. The first specific aim will test the importance of neuronal vs. humoral signals in the regulation of peripheral oscillator phase. The asymmetrical haPer1expression in the SCN of Syrian hamsters held in constant light that show split locomotor behavior will be used to determine if a similar level of asymmetry of clock gene expression in the left and right sides of the body in bilaterally paired organs is accomplished by lateralized neuronal projections of the SCN. Asymmetrical expression of physiologically important genes in these peripheral organs will also be assessed. Specific aim 2 will determine if a molecular clock oscillates within arousal-promoting neurons, specifically the hypocretin-expressing neurons of the LH/DMH and the tyrosine hydroxylase-expressing cells of the locus coeruleus. Specific Aim 3 will utilize the behaviorally split Syrian hamster to determine if lateralized projections from the SCN control the phase of clock gene expression within these arousal-promoting neurons.