A microfluidic-induced C. elegans sleep state

Abstract

An important feature of animal behavior is the ability to switch rapidly between activity states, however, how the brain regulates these spontaneous transitions based on the animal's perceived environment is not well understood. Here we show a C. elegans sleep-like state on a scalable platform that enables simultaneous control of multiple environmental factors including temperature, mechanical stress, and food availability. This brief quiescent state, which we refer to as microfluidic-induced sleep, occurs spontaneously in microfluidic chambers, which allows us to track animal movement and perform whole-brain imaging. With these capabilities, we establish that microfluidic-induced sleep meets the behavioral requirements of C. elegans sleep and depends on multiple factors, such as satiety and temperature. Additionally, we show that C. elegans sleep can be induced through mechanosensory pathways. Together, these results establish a model system for studying how animals process multiple sensory pathways to regulate behavioral states.

C. elegansepisodic swimming is driven by multifractal kinetics

“…Experimental measurements of temporal changes in biological system variables of interest and the statistical analysis of those data can provide information about the hidden operating principles of that system 43 . C. elegans episodic swimming was characterized conventionally by the average residence time of active- and inactive-states 23–25,44 . Here, we applied fractal analysis to study the molecular and genetic mechanisms regulating animal behavior over a 6-d period recorded at a subsecond temporal resolution, showing that episodic swimming is a scale-free process across a 1000-fold range of time scales (Fig.…”

A quiescent state following mild sensory arousal in Caenorhabditis elegans is potentiated by stress

“…Compared to these pauses, PRQ is much longer in duration and occurs with a delay relative to the stimulus. As another example, animals confined to small spaces engage in long-term quiescent behavior 60 . PRQ occurs more quickly and is much shorter in duration than this confinement induced quiescence.…”

Bioelectronics for Millimeter-Sized Model Organisms

“…The combination of C. elegans wholebrain imaging, behavior, and electrophysiology can provide a versatile platform for studying the neural circuit basis of behavior. For example, nano-SPEAR electrophysiological recordings in adult worms led to the discovery of a microfluidic-induced sleep state (Gonzales et al, 2017) ( Figure 3A), which was further dissected with behavioral assays, genetic manipulations, and whole-brain imaging ( Figure 3B) (Gonzales et al, 2019). In addition, these recording modalities can be combined with the precise environmental control offered by small microdevices, giving the ability to study how nematode circuits integrate external environmental cues and drive behavioral-state transitions, such as sleep-wake switching ( Figure 3B) (Gonzales et al, 2019;Nichols et al, 2017;Skora et al, 2018).…”

“…Microfluidic valves, typically used to control fluidic flow (Unger, 2000), can also be incorporated into bioelectronic devices for spatiotemporal control of mechanical stimuli (Cho et al, 2017b;Gonzales et al, 2019;McClanahan et al, 2017;Nekimken et al, 2017). The strength of these stimuli can be regulated by controlling the pressure used to rapidly inflate the valve.…”

“…The strength of these stimuli can be regulated by controlling the pressure used to rapidly inflate the valve. When combined with behavioral measurements or calcium imaging, devices can be scaled for high-throughput assays of C. elegans touch responses (McClanahan et al, 2017), revealing how mechanosensory neurons respond to touch (Cho and Sternberg, 2014;Nekimken et al, 2017), and used as a technique to test changes in sensorimotor responses during sleep (Gonzales et al, 2019). Finally, as with chemical and mechanical stimuli, the environmental temperature can be temporally controlled.…”