Sleep problems are extremely common among individuals with autism, and it is likely that they contribute to other features of the condition. However, we don’t know yet to what extent sleep disruption leads to the cognitive aspects of autism.
One problem is our limited understanding of the function of sleep in cognition. EEG provides only superficial measures of brain activity, and yet circuits critical for sleep are located deep in the brain.
In my lab, we are studying the function of sleep and these neural networks using mouse and zebrafish. Zebrafish embryos are completely transparent, so you can look deep inside their brains, which share core commonalities with ours.
We can use whole-brain imaging and fluorescent proteins to record the activity of each neuron in the fish brain. This allows us to characterize the effects of sleep on the entire brain, not just at its surface. We can then identify networks of neurons critical for sleep.
In mice and zebrafish, we can then use techniques such as optogenetics and pharmacological tools such as hypnotics to manipulate specific networks. These methods may help us manipulate sleep and arousal states that are crucial for optimal memory and cognition. Once we know the role of each network in maintaining normal sleep architecture, we can look for disruptions in mouse models of autism.
We hope our findings will one day allow researchers to target certain neural networks in people with autism to improve sleep, and that this, in turn, will ease other features of the condition. The challenge is getting the funds to do these important experiments.
The current funding climate pushes researchers to work on animals that are more closely related to people than zebrafish are. Yet zebrafish embryos are the only see-through vertebrate model that allows us to explore the entirety of a brain similar to ours, and to discover the intimate cellular and neuronal mechanisms that underlie complex behaviors.