Social Isolation Timer and Sleep Homeostat

The hemibrain dataset - the electron microscopy-based fully reconstructed synaptic-level connectome of the Drosophila central brain - theoretically predicted that a specific neuron type, hDeltaK, exhibits strong synaptic connections with the known sleep-wake network in Drosophila (Hulse et al., eLife 2021). We have determined that hDeltaK is the primary constituent of P2 neurons (Li et al., Nature 2021). Our work has provided the first experimental evidence that hDeltaK (P2 neurons) participates in sleep-wake networks in a peculiar way: it regulates chronic social isolation-induced sleep loss. We propose that these neurons act like an “isolation stopwatch” and contribute to the “isolation timing” during chronic social isolation. We are currently working on identifying neural substrates in hDeltaK, and neural circuits connecting with hDeltaK, which underlie social isolation-induced sleep loss using state-of-the-art genomics and imaging methods. These neural substrates and circuits will reveal: (a) principles of sleep and wakefulness control; (b) molecular and circuit mechanisms underlying the passage of time during chronic social isolation.