Scientists Identify Brain Switch That Controls a Vital Survival Instinct in Organisms

Knowing when to head out looking for food and when to stop and eat is an important judgement call for any species that wants to survive for an extended period of time.

The discovery of the brain of the Caenorhabditis elegans worm has given researchers confidence that they can understand how these processes work in other animals as well.
Scientists don't understand much about how brains can learn long-term behavioral habits while also being flexible enough to change them if the current situation warrants it.

Steven Flavell from the Massachusetts Institute of Technology says that the decision to roam or to dwell will have a big impact on the worm's survival.

"We thought that studying how the brain controls this crucial decision-making process could uncover fundamental circuit elements that may be deployed in many animals' brains."

The team went as far as developing a whole new type of microscope that enabled them to track neuron activity through calcium traces that triggered flashes of light, while the animals moved.

The activity was mapped to the behaviors of the worm and the links between them were found. The software was trained to predict what a worm would do based on how it was firing.

The process was able to identify four neurons that were associated with the act of roaming around hunting for food. The firing of a single neuron called NSM was linked to the fact that people were dwelling in places.

There are organisms under a microscope. (MIT)

The team worked out that the two processes were blocking each other. The four cells produced a chemical called PDF to suppress the other cells.

The analysis showed that the switch between the four neurons was flipped by a neuron known asAIA. Studies have shown that the smell of food is an important triggering factor.

Food odors are an important sensory cue for a worm.

AIA's ability to detect food odors and transmit that information to these different downstream circuits, dependent on other incoming cues, allows animals to contextualize the smell.

The brain circuits that are roaming or feeding will work with the food smells. If the worm can smell food but also know it's eating, the researchers will continue working with NSM to keep feeding.

If the worm can't smell food, and it's not eating, the worm will be switched to the roaming circuit.

The more we know about the brain in worms and other animals, the better we can understand how behaviors are controlled. Discoveries like this can help with a lot of things.

AIA stands out as a basic motif that could allow for context- dependent behaviors, if you are looking for circuit elements that could also be operating in bigger brains.

The research has been published.