Sleep-plasticity and sleep-dependent plasticity
Our recent work speaks to two aspects of sleep in Drosophila - that sleep is plastic, i.e modifiable, and in turn supports neural plasticity.
In defining a novel sleep regulatory pathway and demonstrating how sleep supports adaptive behavior, our work speaks to both the how and the why of sleep. Going forward, we want to build on this work at Ashoka, to explore mechanisms of sleep-plasticity and sleep-dependent plasticity in healthy and impaired brains. Read more about it or watch a seminar I gave at the University of Missouri, Kansas City below.
In defining a novel sleep regulatory pathway and demonstrating how sleep supports adaptive behavior, our work speaks to both the how and the why of sleep. Going forward, we want to build on this work at Ashoka, to explore mechanisms of sleep-plasticity and sleep-dependent plasticity in healthy and impaired brains. Read more about it or watch a seminar I gave at the University of Missouri, Kansas City below.
Sleep-plasticity: Flight and Sleep
We uncovered a surprising relationship between flight and sleep in Drosophila – impairing flight increases sleep. Further, we traced a novel circuit through 3 synapses from wing pheromone sensing neurons to the brain that mediates this effect.
These data suggest that sleep can be plastic and responsive to changes in the environment animals encounter. Indeed, an influential theory of sleep – adaptive inactivity – suggests that when animals are in harmful or dangerous situations, they sleep to stay out of harm’s way. Sleep in these circumstances might facilitate plasticity enabling animals to adapt to novel circumstances. These results provide experimental and mechanistic support to this hypothesis that had observational support but had been hard to understand mechanistically. Further, they define a novel and unexpected sleep promoting pathway, and suggest that pheromone sensing neurons can be repurposed to convey information about wing-integrity and regulate sleep. Variations on the theme of 'external' signals regulating the 'internal' state of sleep are likely to be common. This manuscript was published in Science Advances in 2020, and has been covered in numerous media outlets. |
Sleep and Plasticity
In humans, declarative memories i.e. memories of episodes and facts, particularly benefit from sleep, and are labile to degradation with age or neurodegeneration. Spatial learning in animals has many similarities with human declarative memories, suggesting that spatial learning in animals can model human declarative memories.
Here, we adapted a spatial learning assay to study the relationship between sleep and plasticity. The assay uses a ‘thermal maze’ of Peltier plates maintained at 36-37°C. Flies are tasked with locating the one cool tile on a hot plate using distal visual cues. Amongst other findings, we found that flies exhibited dramatic age-dependent decline in spatial learning which were reversed by enhancing sleep or dopaminergic signalling. Together with previous work, these results suggest a surprising restorative dimension to the sleep-plasticity relationship. Further, they suggest that sleep could function as a therapeutic, a finding of great public-health significance given a large aging population. These data were recently published in the journal Sleep |
I recently spoke about both of these stories in a seminar at the University of Missouri, Kansas City below:
Cover Image: Detail from a Folio depicting the fable of the "The Seven Sleepers" taken from a 16th Century Falnama. The story is a fable in Islamic and Christian lore, of seven youth who, facing religious persecution slept in a cave to escape the evil King. The youth are thus in a way, "sleeping to stay out of harm's way". Image from the Metropolitan Museum of Art, in the public domain.