Psychology Commons^™

Distinct Retinohypothalamic Innervation Patterns Predict The Developmental Emergence Of Species-Typical Circadian Phase Preference In Nocturnal Norway Rats And Diurnal Nile Grass Rats, William D. Todd, Andrew J. Gall, Joshua A. Weiner, Mark S. Blumberg

Faculty Publications

How does the brain develop differently to support nocturnality in some mammals, but diurnality in others? To answer this question, one might look to the suprachiasmatic nucleus (SCN), which is entrained by light via the retinohypothalamic tract (RHT). However, because the SCN is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. In adult Norway rats (Rattus norvegicus), which are nocturnal, the RHT also projects to the ventral subparaventricular zone (vSPVZ), an adjacent region that expresses an in-phase pattern of SCN-vSPVZ neuronal activity. In contrast, in adult Nile grass rats (Arvicanthis …

Developmental Emergence Of Power-Law Wake Behavior Depends Upon The Functional Integrity Of The Locus Coeruleus, Andrew J. Gall, Badal Joshi, Janet Best, Virginia R. Florang, Jonathan A. Doorn, Mark S. Blumberg

Faculty Publications

STUDY OBJECTIVES:

Daily amounts of sleep and wakefulness are accumulated in discrete bouts that exhibit distinct statistical properties. In adult mammals, sleep bout durations follow an exponential distribution whereas wake bout durations follow a power-law distribution. In infant Norway rats, however, wake bouts initially follow an exponential distribution and only transition to a power-law distribution beginning around postnatal day 15 (P15). Here we test the hypothesis that the locus coeruleus (LC), one of several wake-active nuclei in the brainstem, contributes to this developmental transition.

DESIGN:

At P7, rats were injected subcutaneously with saline or DSP-4, a neurotoxin that targets noradrenergic …