2023-07-18 13:28:07
The Drosophila fly, a small insect of choice for scientific research, knows how to evaluate quantities of objects, confirmed a French team from the Brain Institute, by identifying the kind of neurons at work.
The ability to perceive quantity-related information exists in many vertebrates and invertebrates, postdoctoral neuroscientist Mercedes Bengochea explained in a Brain Institute statement. A capacity documented as well in primates as in fish or even bees.
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Drosophila is also known as the fruit fly.
Photo : iStock
It remains to discover the neural circuits making this task possible, in which it is not necessary to know the concept of number to distinguish between one, two, several and many, adds the first author of the study published last week in Cell Reports (New window) (in English).
This is where comes in Drosophilia melanogaster, a tiny insect no more than a few millimeters long, which every fruit lover has seen circling around a basket. Easy to raise, it is an ideal guinea pig for many experiments, especially in genetics.
In this case a model of choice for studying cognition, according to the member of the Brain Development team. The researchers knew that, faced with a threat, the little fly tends to adjust its behavior according to the number of congeners likely to help it. From there to imagine that she can evaluate this number …
The team placed the fly in a small arena on the walls of which faced two distinct groups of black shapes, then filmed the preferential area where the fly was flying. Conclusion: Drosophila generally preferred the group containing the most objects. Three against one, or eight against four.
This ability to evaluate the ratio between two quantities, very common in animals, is therefore also present in Drosophila. But the real contribution of the study is to explain how it works. The researchers identified a column of neurons, the LC11, located in the optic lobe and essential for this task.
Once these neurons were neutralized, the flies no longer showed preference for one quantity over another, large or small. Therefore, according to the statement, LC11 neurons are involved in the fly’s defense strategy in the face of a threat.
For Bassem Hassan, head of the Brain Development team, this suggests that the ability to evaluate quantities was decisive in the evolution of invertebrates. With ultimately very simple cognitive solutions.
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