Whole-brain calcium imaging with cellular resolution in freely behaving C. elegans

TL;DR

This paper introduces a novel imaging system that captures whole-brain neuronal activity at cellular resolution in freely moving C. elegans, enabling detailed correlation of neural activity with behavior.

Contribution

The study presents a new imaging instrument combining spinning-disk confocal microscopy and real-time tracking to record activity from all neurons in freely moving worms.

Findings

Recorded calcium activity from 78 neurons during behavior.

Identified neurons correlated with forward, backward, and turning movements.

Validated known neural circuits and discovered new candidate neurons.

Abstract

The ability to acquire large-scale recordings of neuronal activity in awake and unrestrained animals poses a major challenge for studying neural coding of animal behavior. We present a new instrument capable of recording intracellular calcium transients from every neuron in the head of a freely behaving C. elegans with cellular resolution while simultaneously recording the animal's position, posture and locomotion. We employ spinning-disk confocal microscopy to capture 3D volumetric fluorescent images of neurons expressing the calcium indicator GCaMP6s at 5 head-volumes per second. Two cameras simultaneously monitor the animal's position and orientation. Custom software tracks the 3D position of the animal's head in real-time and adjusts a motorized stage to keep it within the field of view as the animal roams freely. We observe calcium transients from 78 neurons and correlate this activity with the animal's behavior. Across worms, multiple neurons show significant correlations with modes of behavior corresponding to forward, backward, and turning locomotion. By comparing the 3D positions of these neurons with a known atlas, our results are consistent with previous single-neuron studies and demonstrate the existence of new candidate neurons for behavioral circuits.