It's a common belief that when you think of neurobiology you often imagine the brain and the central nervous system one neuron at a time. And for many years, that's exactly how researchers had to approach the larger questions. By tagging in particular neurotransmitters, that would convey the passing of one signal from neuron to neuron, researchers were able to follow the path of a signal back and forth along an axon. But now, with new imaging technology and a new model organism in mind, researchers in neurobiology are seeking new ways in which we study the brain-mapping neural circuits and their functions in great detail, on the large scale.
Publishing their results this week in the journal Neuron, researchers with the University of Manchester and the Rosalind Franklin University of Medicine & Science turned to sea slugs for their answers. Looking into how neurons fired in the brain of large sea slugs (Aplysia species) the researchers were able to discover a uniquely broad view thanks in part to the sea slugs' unique neural circuitry.
"What happens in the brain during movement is currently only well understood for small, dedicated neural circuits" lead author of the study, Dr. Mark Humphries of Medical Research Council at Manchester says. "The sea slug brain has some of the complexity of higher organisms, yet has large neurons that make it possible to record a substantial amount of what is happening in the brain during movement."
Capable of imaging the slugs' movements and neural activations all at once, along the length of the organism, was beneficial to researchers as they were able to gather immense amounts of data all at once. Then theoreticians were able to decode the large amounts of data to find a method to the neurological madness. Instead of just seeing the neural pathways illuminate almost all at once, researchers were able to decipher the pathways involved in movement, and were able to attribute each neural cavity with a specific function.
But the researchers know that the challenge is not over yet. While their new study reveals a fairly ornate method of complex locomotion, that occurs through the interconnected motions of a locomotive network, applying these methods to humans will be endlessly more difficult for a number of reasons. But while it may be difficult the team is up to the task, and they believe that using the Aplysias as models has helped them learn how to decipher the information that they will need to do in humans, as well.
"Describing the dynamics of a neural population and decoding the neural program is still very challenging" Humphries says. "We hope that this research will help to build a language and toolkit for future researchers using any network-scale recording technology."
"This research introduces new methods for pulling apart neural circuits to expose their inner building blocks. Our methods could be used to help understand how brain networks change in disease states and how drugs act to restore normal brain function."
