The ants' brain has a kind of communications control center specialized in receiving and interpreting alarm signals (dangers) that are transmitted between individuals through pheromones. This is the main discovery (actually, for the moment, a hypothesis) presented in the conclusions of a study led by experts from the Rockefeller University (New York, United States), published in an article in the journal Cell (online edition). line of June 14)
The ability of ants to communicate, through physical and chemical signals, has been studied for years, but even the best myrmecologists admit that they still haven't fully understood how this type of process works and how these tiny insects process data, with extremely small brains
The novelty of the study that is now being published is the presentation of new data on the pheromones that signal danger, that is, the scent markers that ants emit to communicate with each other in alarm situations, and the interpretation of these signals in a specific part of the brain. Specifically, the authors claim to have identified "a central sensory center glomerulus for alarm behavior." A glomerulus is a spherical structure located in the olfactory bulb of the brain, where synapses form between the olfactory nerve terminals and the mitral dendrites,
"Humans are not the only animals with complex societies and communication systems," explains lead author of the scientific paper, Taylor Hart of Rockefeller University. "Throughout evolution, ants have evolved extremely complex olfactory systems compared to other insects, which allows them to communicate using many different types of pheromones that can mean different things."
This research suggests that ants have their own kind of communication center in their brains, a system much more sophisticated than other insects, including bees. In this center, or glomerulus, the alarm pheromones, or "danger signals," of other ants are specifically interpreted. Until now it was believed that these types of responses were processed in various parts of the brain, without knowing a specific glomerulus.
It would therefore be "a sensory center in the ant's brain to which all panic-inducing alarm pheromones are directed," says co-author Daniel Kronauer, also from Rockefeller University.
The researchers used an engineered protein called GCaMP to scan the brain activity of clonal raider ants that were exposed to danger signals. GCaMP works by binding to calcium ions, which flare up with brain activity, and the resulting fluorescent chemical compound can be seen in high-resolution microscopes adapted to view them.
Running the scans, the researchers noted that only a small section of the ants' brains lit up in response to danger signals, but the ants still displayed complex and immediate behaviors in response. These behaviors were called the "panic response" because they involved actions such as running away, evacuating the nest, and transporting their young from the nest to a safer location.
Ant species with different colony sizes also use different pheromones to communicate a variety of messages. "We think that in nature, clonal raider ants (Ooceraea biroi) typically have a colony size of only tens to hundreds of individuals, which is quite small as far as ant colonies go," says Hart. "Often these small colonies tend to have panic responses as alarm behavior because their main goal is to escape and survive. They can't risk many people. Army ants, the cousins of clonal raider ants, have massive colonies. — hundreds of thousands or millions of individuals—and they can be much more aggressive."
Regardless of species, ants within a colony are divided by caste and role, with ants within different castes and roles having slightly different anatomy. For the purposes of this study, the researchers chose clonal raider ants as the species because they are easy to control. They used ants of one sex within one caste and role (worker ants) to ensure consistency and therefore make it easier to observe generalized patterns. Once researchers have a clearer understanding of the neural differences between castes, sexes, and roles, they will be able to better understand exactly how different ant brains process the same signals.
"We can start to see how these sensory representations are similar or different between ants," says Hart. Kronauer says: "We are looking at the division of labor. Why do individuals who are genetically the same take on different tasks in the colony? How does this division of labor work?"
