Final Report Summary - ELEGANSNEUROCIRCUITS (Neuromodulation of Oxygen Chemosensory Circuits in Caenorhabditis elegans)
A fundamental problem in neuroscience is to decipher how neuronal networks in the brain integrate information from the environment with the internal state of the animal to generate decisions and appropriate behaviors. This ERC funded project enabled some milestone achievements towards a better understanding of these processes. The model organism of our studies was a tiny soil worm named C. elegans, which, despite a small nervous system, performs complex behaviors. We developed a new experimental approach that enabled us to record the activity of nearly all nerve cells in the brain. We made the astounding discovery that neuronal networks across the entire brain exhibit rich spontaneous activity dynamics. These dynamics are highly coordinated and occur even in the absence of any acute stimuli from the environment. Computational analysis and additional experiments enabled is to decode the behavior of the animals from these whole brain recordings; literally, we are able now to read the minds of worms. Next, we focused our studies on how brain dynamics change during different internal states, like hunger and satiety or sleep and wakefulness. Our unique approach uncovered that sleep is affecting the majority of all brain cells and that it can arise spontaneously, given that the animals are in tired conditions. However, alerting sensory inputs can rapidly revert the brain to an aroused state of wakefulness. This work supports a long-standing hypothesis that sleep is an emergent property of neuronal networks; yet the brain exerts control via specific arousal and sleep promoting neuronal circuits.