Researchers at Princeton University (NJ, USA) have successfully recorded neural activity throughout most of the brain of the model nematode, Caenorhabditis elegans. In doing so the study represents one of the first successful attempts to both record neural activity and to correlate this activity with specific behaviors in a free-moving animal. The team hope that both the recordings and the technique used to generate the recordings, published recently in Proceedings of the National Academy of Sciences, could help to further understand the coordination of action and perception in animals.
The technique developed allowed the research team to record 3D footage of neural activity within C. elegans, focusing on 77 neurons of a total of 302 neurons present within the nervous system of the 1mm worm. The tool designed focused on measuring calcium levels, as an indicator of cell activity, within the brain cells during any interactions. A calcium indicator was utilized as a fluorescent marker of calcium.
The nematodes’ movements and neuron-level calcium activity were measured for over 4 minutes and software designed by the researchers enabled 3D monitoring of the position of the animal’s head in real-time. The activity of each of the 77 neurons was then correlated with individual behaviors including forward and backwards movement as well as changes in direction.
Study author Andrew Leifer (Princeton University) commented on the importance of the work: “This system is exciting because it provides the most detailed picture yet of brain-wide neural activity with single neuron resolution in the brain of an animal that is free to move around.” Prior to this, neuron activity studies have been restricted to either small brain subregions or to organisms that are unconscious or limited in movement.
The simple nervous system of C. elegans in comparison to humans and other animals provided researchers with a more manageable opportunity to evaluate the efficacy of their recording equipment. It also however revealed information on neuron coordination that could be translated to larger, more complex organisms. “By studying how the brain works in a simple animal like the worm we hope to gain insights into how collections of neurons work that are universal for all brains, even humans,” remarked Leifer.
“These recordings are very large and we have only begun the process of carefully mining all of the data,” explained Leifer. The team are now looking to use the correlations initially revealed to help to build new models of brain functioning.
“Neuroscience is at the beginning of a transition towards larger-scale recordings of neural activity and towards studying animals under more natural conditions. This work helps push the field forward on both fronts,” Leifer concluded.