Almost all animals require sleep to function. The physiologic reasons for the need for sleep are not well understood. The Institute scientists have suggested the “Neural Reapportionment” hypothesis, which suggests that sleep is necessary in order for the body to reapportion or redistribute its various resources which may be depleted, or moved/dispersed during wakeful periods. Experiments are underway to test this hypothesis by looking at how redistribution and readjustment of neurotransmitters like glutamate, and intercellular movement of mitochondria may be dependent on sleep.

Sleep Studies in Fruit Flies

Sleep and Social Interaction
Researchers at the Institute were the first to show that Drosophila have sleep behavior and patterns similar to those in mammals. More recent findings relate sleep patterns in fruit flies to visual and olfactory stimulation as well as social interaction. Sleep amounts seem to increase linearly with intensity of social interaction.

Dopamine and Arousal
We have devised experiments to see what effects methamphetamines (METH) can have on sleep pattern of fruit flies. Our researchers have found that administration of this drug results in wakefulness and increased motor activity. In addition, our results demonstrate that flies show increased sexual arousal in response to METH. However, they become less successful at mating. These results indicate that METH ingestion leads to increased or decreased dopamine levels and degradation of complex behavior.

Visual Perception and Arousal
At the Institute we have devised novel methods for studying the state of arousal in the fruit fly Drosophila. Flies are tethered to a post by their head and body, and they are free to move their legs and wings while their brain activity is measured. Coupled body movement and measured brain activity indicates general state of arousal and wakefulness, as apposed to lowered mechanical and brain activity during sleep. In order to study the ability of flies to focus on sensory simulation, flies are run in “optometer” mazes presenting patterns of dark and light strips. The flies’ visual perception and attention-like responses can be measured in this type of visual maze. We have been able to confirm visual attention-deficit for key mutants of Drosophila.

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