P169 Anesthesia modulates the system-wide contributions of identified head neurons in C. elegans
Avraham Lepsky*¹, Andrew Chang², Chris Connor³, Chris Gabel³
¹ Graduate Program for Neuroscience, Boston University, Boston, United States
² Graduate Program in Physiology, Boston University, Boston, United States
³ Department of Biophysics, Boston University, Boston, United States
*Email: avil@bu.edu
Introduction
While anesthesia has similar effects in the brains of animals ranging from the nematode C. elegans to humans, the mechanism by which various anesthetic agents work remains largely unknown. C. elegans has been identified as a tractable model for studying anesthesia due to progressing behavioral deficits from increased anesthesia concentration, genetic susceptibility analogous to mammals, and an annotated neuroconnectome [1]. Isoflurane is a volatile anesthetic that induces general anesthesia; previous work has found that isoflurane anesthesia in C. elegans caused marked dyssynchrony of neuron dynamics (as measured by a decrease in the cumulative variance explained by the top 3 principal components in neuronal activity) [2].
Methods
We employed C. elegans worms expressing the NeuroPAL transgene, providing a fluorescent color map for identification of neurons within the known connectome of the C. elegans nervous system [3]. Using light sheet microscopy performed by a dual inverted selective plane illumination microscope (DISPIM), we measured activity of 120 individual head neurons of the NeuroPAL worms via fluorescence imaging of the calcium sensitive GCaMP reporter. We imaged for 20 minutes at 2Hz. We performed principal component analysis (PCA) on the measured 120 neuron activity dynamics, following previous attempts at ascribing a neural manifold to C. elegans behavior [4] with the added information of neuron identification.
Results
Analysis of neuronal activity across worms at various isoflurane levels identified 10 neurons with a statistically significant change in PCA magnitude between 0 and 2% isoflurane and 17 neurons between 0 and 4%. No obvious receptor or functional identity marker was shared by all statistically significant neurons.
Discussion
We identified a list of neurons whose contributions to the system’s activity are most significantly modulated by changing isoflurane concentration. Because the connectome of C. elegans has been established, the anatomical properties of the neurons can be compared to their functional properties to establish a mechanistic understanding of the systemic changes induced by isoflurane. Connectomic spiking neuron models and other biophysical models can then be used to make predictions linking the molecular and behavioral properties of anesthetic agents.
Acknowledgements
Thank you to the Graduate Program of Neuroscience, under the direction of Dr. Shelly J. Russek and Sandi Grasso, for providing such a nurturing community.
Funding was generously awarded through a T32 grant.
References
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