The Substructure of the Suprachiasmatic Nucleus: Similarities between Nocturnal and Diurnal Spiny Mice

Cohen, Rotem; Kronfeld‐Schor, Noga; Ramanathan, Chidambaram; Baumgras, Anna; Smale, Laura

doi:10.1159/000282172

Cited by 34 publications

(26 citation statements)

References 154 publications

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“…Work in animal models has revealed that the suprachiasmatic nucleus (SCN) is the main chronobiological pacemaker involved in generating and coordinating circadian rhythms [24]. The SCN receives photic inputs (via the retinohypothalamic tract in the optic nerve) and non-photic inputs, which synchronize these rhythms to 24-hour cycles in the environment.…”

Section: Circadian Rhythm Disordersmentioning

confidence: 99%

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Sleep disturbances in multiple sclerosis

Caminero

Bartolomé

2011

Journal of the Neurological Sciences

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Section: Circadian Rhythm Disordersmentioning

confidence: 99%

“…The SCN receives photic inputs (via the retinohypothalamic tract in the optic nerve) and non-photic inputs, which synchronize these rhythms to 24-hour cycles in the environment. The outputs distribute rhythmic signals from the SCN to brain regions that more directly regulate behavior and physiology [24].…”

Section: Circadian Rhythm Disordersmentioning

confidence: 99%

Sleep disturbances in multiple sclerosis

Caminero

Bartolomé

2011

Journal of the Neurological Sciences

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“…Surprisingly, however, there are no systematic differences in circadian function between nocturnal and diurnal mammals [12]. In both groups, the SCN is similar in structure [13] and has highest neuronal firing rates during circadian daytime [14]. Furthermore, melatonin secretion, which is under SCN control in mammals, always occurs during circadian nighttime [15].…”

Section: Introductionmentioning

confidence: 97%

Mammalian Rest/Activity Patterns Explained by Physiologically Based Modeling

et al. 2013

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Circadian rhythms are fundamental to life. In mammals, these rhythms are generated by pacemaker neurons in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is remarkably consistent in structure and function between species, yet mammalian rest/activity patterns are extremely diverse, including diurnal, nocturnal, and crepuscular behaviors. Two mechanisms have been proposed to account for this diversity: (i) modulation of SCN output by downstream nuclei, and (ii) direct effects of light on activity. These two mechanisms are difficult to disentangle experimentally and their respective roles remain unknown. To address this, we developed a computational model to simulate the two mechanisms and their influence on temporal niche. In our model, SCN output is relayed via the subparaventricular zone (SPZ) to the dorsomedial hypothalamus (DMH), and thence to ventrolateral preoptic nuclei (VLPO) and lateral hypothalamus (LHA). Using this model, we generated rich phenotypes that closely resemble experimental data. Modulation of SCN output at the SPZ was found to generate a full spectrum of diurnal-to-nocturnal phenotypes. Intriguingly, we also uncovered a novel mechanism for crepuscular behavior: if DMH/VLPO and DMH/LHA projections act cooperatively, daily activity is unimodal, but if they act competitively, activity can become bimodal. In addition, we successfully reproduced diurnal/nocturnal switching in the rodent Octodon degu using coordinated inversions in both masking and circadian modulation. Finally, the model correctly predicted the SCN lesion phenotype in squirrel monkeys: loss of circadian rhythmicity and emergence of ∼4-h sleep/wake cycles. In capturing these diverse phenotypes, the model provides a powerful new framework for understanding rest/activity patterns and relating them to underlying physiology. Given the ubiquitous effects of temporal organization on all aspects of animal behavior and physiology, this study sheds light on the physiological changes required to orchestrate adaptation to various temporal niches.

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“…, Cohen and Kronfeld‐Schor , Refinetti , , Hagenauer and Lee , Cohen et al. , b, Tomotani et al. , Barak and Kronfeld‐Schor , Tachinardi et al.…”

Section: Introductionmentioning

confidence: 99%

Time and ecological resilience: can diurnal animals compensate for climate change by shifting to nocturnal activity?

Levy

Dayan

Porter

et al. 2018

Ecological Monographs

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100

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Considerable research is aimed at developing predictions of ecosystem responses to climate change, focusing on the spatial scale, such as range shifts and contractions, as well as activity restrictions to shaded microhabitats. On the other hand, the ability of species to shift their activity times during the diel cycle, and consequently to alter the environment in which activity occurs, has been largely neglected. Daily activity patterns are perceived as fairly fixed; however, natural changes in activity patterns have been reported in increasing numbers of species. Here, we present a framework that explores how shifts in activity patterns may buffer impacts of climate change. To demonstrate our framework, we simulated costs of activity of diurnal and nocturnal rodents and showed that future summers may decrease the energetic demands of nocturnal mammals while increasing water demands of diurnal mammals. Climate projections suggest that vegetation cover and water availability will decrease under future climate scenarios, especially in areas where water demands are expected to increase the most. These changes are expected to limit the ability of diurnal animals to restrict activity to shaded microhabitats and to keep a positive water balance. Our analysis shows that by shifting to nocturnality, diurnal mammals may mitigate the high water costs of future summers. We suggest that future research should explore the role of the diel time axis as an ecological resource when predicting the impacts of climate change.

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The Substructure of the Suprachiasmatic Nucleus: Similarities between Nocturnal and Diurnal Spiny Mice

Cited by 34 publications

References 154 publications

Sleep disturbances in multiple sclerosis

Sleep disturbances in multiple sclerosis

Mammalian Rest/Activity Patterns Explained by Physiologically Based Modeling

Time and ecological resilience: can diurnal animals compensate for climate change by shifting to nocturnal activity?

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