Sensory Arousal During Stress-Induced Sleep

Students

2020
Engineering and Applied Sciences

Faculty

Wilf Family Term Assistant Professor of Bioengineering

Project Summary

This summer I had the opportunity to develop my own research project while working in a lab dedicated to understanding neural circuits and behavior. My project’s focus was on sleep and the mechanism by which organisms become aroused from sleep upon sensing external stimuli. As part of an engineering lab, I developed both hardware for a unique vibration assay and software to analyze its data using simple machine vision and image processing. Ultimately, the goal of this technology was to better approach and measure properties of sleep to answer underlying biological questions.

Sleep is a conserved process across phyla, thought to be an integral part of bodily repair and homeostasis. Several common traits of sleeping states include reduced sensory responsiveness, reduced arousal threshold, and a rapid reversal of sleep state following a strong stimulus. There are two recognized types of sleep: circadian sleep, which is genetically regulated and occurs periodically, and stress-induced sleep (SIS), which shares many of the behavioral characteristics of circadian sleep and results from external aggravations such as viral infection, ultraviolet radiation, and heat shock. The latter type is dose-dependent, and therefore aspects of sleep pertaining to its depth may be manipulated.

I studied sleep in C. elegans, a model organism nematode whose simple nervous system is well characterized. The worm is an advantageous choice to study sleep in because its two versions of sleep – circadian and stress-induced – are entirely independent. Circadian sleep is limited to the inter-larval stages of ­C. elegans development, so sleep in adults may be artificially introduced and controlled through external stressors. I chose UV radiation as an external stressor, and monitored motion and posture during sleep, as well as lifespan and breeding to describe the dose-dependent property of SIS. Worms were placed in wells of a WorMotel, a microfluidic made of PDMS polymer which houses worms separately on individual agar wells, and imaged the worms under a camera over the course of sleep. Stimuli were provided by vibrations from a speaker underneath; this gentle mechanical stimulus results in an acute movement of the worms which can be quantified to measure response during sleep.

The PURM program provided me with a valuable chance to learn how classroom knowledge is transferred to the next level in graduate school and primary research. I learned how to develop and ask meaningful questions which I may then approach experimentally. Within the context of biomedical research, I became more familiar with the state of the field of C. elegans research and the process of producing a peer-reviewed scientific paper. I honed my skills with machinery and circuitry and worked an extensive amount writing custom MATLAB scripts - software to convert and perform calculations on what the camera sees to produce meaningful data. Most importantly, I learned how to fail. There were inevitably lots of bumps and bugs when developing an experimental design from the ground up, and I experienced firsthand how to approach a failed result with a ‘fix-it’ mentality as an opportunity to build upon and improve my design.

Sensory Arousal During Stress-Induced Sleep