Summary The role of the trans-membrane receptor Notch in the adult brain is poorly understood. Here, we provide evidence that bunched, a negative regulator of Notch is involved in sleep homeostasis. Genetic evidence indicates that interfering with bunched activity in the mushroom bodies (MBs) abolishes sleep homeostasis. Combining bunched and Delta loss-of-function mutations rescued normal homeostasis, suggesting that Notch signaling may be involved in regulating sensitivity to sleep loss. Preventing the down regulation of Delta by over-expressing a wild-type transgene in MBs reduces sleep homeostasis and, importantly, prevents learning impairments induced by sleep deprivation. Similar resistance to sleep loss is observed with the Notchspl-1 gain-of-function mutants. Immunohistochemistry reveals that the Notch receptor is expressed in glia, whereas Delta is localized in neurons. Importantly the expression of the intracellular domain of Notch, a dominant activated form of the receptor, in glia is sufficient to prevent learning deficits after sleep deprivation. Together these results identify a novel neuronal-glia signalling pathway dependent on Notch and regulated by bunched. These data highlight the emerging role of neuron-glia interactions in regulating both sleep and learning impairments associated with sleep loss.

Although it is unknown how much translational displacement of the syndesmosis is acceptable, it seems that the experienced surgeon will be able to reduce the joint within 2.5 mm and that fluoroscopic comparisons to the normal ankle are helpful in determining malreduction.

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