Biology subjects

Zhang, V. Y.

Publications and source records attributed to Zhang, V. Y..

3 recordsLinked to original sources

bioRxiv2026

Optogenetic activation of parabrachial tachykinin1 neurons drives nonphotic circadian entrainment

Mammalian circadian rhythms are primarily entrained by light, but nonphotic cues can also reorganize behavioral timing through mechanisms that remain poorly understood. Nocturnal foot shocks delivered to rodents while they forage away from the safety of their nesting area have been shown to entrain circadian behavioral rhythms and shift foraging and feeding to the daytime. To identify the neural circuits underlying this nonphotic fear entrainment, we optogenetically stimulated tachykinin 1-expressing neurons in the parabrachial nucleus (Tac1PBN) during the subjective night while the animals foraged outside of their nest, which recapitulated the total activity-rest phase switch in circadian behaviors induced by foot shocks. Furthermore, selective stimulation of Tac1PBN projections to the central amygdala (CeA) produced a significant but reduced phase shift compared to direct stimulation of Tac1PBN cell bodies. When Bmal1, a core clock gene, was conditionally deleted from the CeA, mice failed to fear-entrain, implicating the CeA molecular clock as a necessary component for fear entrainment. Together, these experiments demonstrate that activation of a defined neuronal population outside of the suprachiasmatic nucleus (SCN) can reorganize circadian behavior by engaging a non-SCN circadian oscillator network that requires an intact CeA molecular clock.

neuroscience↗

bioRxiv2025

Modern Times: Longitudinal Study of Toba/Qom Communities Reveals Delay and Shortening of Sleep in Real-Time Across Electrification

While artificial light and digital technologies are widely assumed to delay and curtail sleep, direct, longitudinal evidence documenting these changes is remarkably scarce. From 2012 to 2024, we conducted a longitudinal study of native Toba/Qom communities in northern Argentina, including rural groups newly introduced to electricity and semi-urban groups with earlier access to electricity. Using linear mixed-effects models on a dataset of over 12,000 actigraphically recorded sleep events from 156 participants at different times, we observed striking shifts in sleep dynamics. Remarkably, both groups showed delays of up to 1.4 hours in sleep timing, and participants from rural communities lost a full hour of sleep within just a decade. These changes occurred across a period that included, first, the introduction of electricity to rural communities after 2016, and, in more recent years, the spread of the internet and smartphone use among the Toba/Qom. Our models reveal that these events alone cannot fully explain the observed shifts in sleep timing, suggesting that broader processes of modernization and acculturation, beyond electric light and digital devices alone, may be driving sleep changes. The rapid transformations observed in these communities mirror, within a single decade, the likely trajectory of human sleep across the 20th and early 21st centuries, underscoring the complex ways modern environments reshape sleep behavior.

physiology↗

bioRxiv2023

The circadian molecular clock in the suprachiasmatic nucleus is necessary but not sufficient for fear entrainment in the mouse

Nocturnal aversive stimuli presented to mice during eating and drinking outside of their safe nest can entrain circadian behaviors, leading to a shift toward daytime activity. We show that the canonical molecular circadian clock is necessary for fear entrainment and that an intact molecular clockwork in the suprachiasmatic nucleus (SCN), the site of the central circadian pacemaker, is necessary but not sufficient to sustain fear entrainment of circadian rhythms. Our results demonstrate that entrainment of a circadian clock by cyclic fearful stimuli can lead to severely mistimed circadian behavior that persists even after the aversive stimulus is removed. Together, our results support the interpretation that circadian and sleep symptoms associated with fear and anxiety disorders may represent the output of a fear-entrained clock. One-Sentence SummaryCyclic fearful stimuli can entrain circadian rhythms in mice, and the molecular clock within the central circadian pacemaker is necessary but not sufficient for fear-entrainment.

neuroscience↗