Male fruit flies usually don’t like each other. Socially, they reject their male mates and focus on the females that they recognize via chemoreceptors — or so the scientists thought.
New research by biologists at Cornell University indicates that the fruit fly’s visual system, not just its chemoreceptors, has a large role in its social behaviours. This work highlights the possible origin of differences in human social behaviors, such as those seen in people with bipolar disorder and autism.
This paper is titled “Visual Feedback Neurons Modulate Male Drosophila Courtship Through GABA-mediated Inhibition.” Current Biology on September 5th.
Many animal species use vision to regulate their social behaviour, but the underlying mechanisms are largely unknown. It’s thought that vision in fruit flies is clearly used to detect and track movement, not to regulate social behaviors, but the researchers found that may not be the case.
In our study, we found that hyperactivation of the visual system overcame inhibition from chemical cues emitted by male flies to say to the other male, “Well, you know, I’m another male, don’t mess with me.” Surprisingly, the increase in visual gain in the brain somehow overcomes the inhibition of the chemical senses, which attracts male flies to other males.”
Nilay Yabesi, lead author, assistant professor of neuroscience and behavior
The researchers found that changing GABARAP/GABAa Receptor signaling in visual feedback neurons in the male brain affected the flies’ social inhibitions. When GABARAP is destroyed in the visual system, males unexpectedly show increased courtship toward other males.
The researchers found that genes similar to those in the human brain control the visual neurons of the fruit fly. Decreased GABA signaling in the human brain has been associated with characteristics of social withdrawal in conditions such as autism and schizophrenia.
“Our findings provide a promising avenue for studying how these proteins regulate social behaviors in the mammalian brain and their potential contribution to human psychological states,” said lead author Yuta Mabuchi, MD. 23.
Mabuchi, Y., et al. (2023) Visual feedback neurons modulate courtship in male Drosophila via GABA-mediated inhibition.. Current Biology. doi.org/10.1016/j.cub.2023.08.034.