New research employs innovative tools to reveal how aggressive female fruit flies regulate their vision to concentrate on what matters most.
In most laboratory settings, researchers are typically aligned in their motivations for conducting a study.
However, the Rubin Lab at HHMI’s Janelia Research Campus stands out from regular research facilities.
This lab explores how aggression influences vision in female fruit flies; yet, Senior Group Leader Gerry Rubin is less focused on the exact outcome. Instead, he is more interested in whether the neuroscience tools he has developed over the past decade are sufficient to uncover the mechanisms at play.
Conversely, postdoc Katie Schretter aims to understand the collaborative function of neurons in the fly’s brain to help it zero in on its rival—this understanding will allow her to delve deeper into how social behaviors are controlled.
The new research led by Rubin and Schretter effectively merges their ambitions: it implements groundbreaking tools from Janelia to illustrate how aggressive female fruit flies regulate their vision to prioritize critical information. By utilizing the fruit fly connectome—a comprehensive mapping of all neurons and their connections within the brain—and genetically modified flies, the researchers revealed how the flies’ neurons and circuits collectively manage visual information flexibly depending on different scenarios.
Learning how a social behavior such as aggression affects vision at the neuronal and circuit level in fruit flies could shed light on similar processes in other species, including humans. Greater insight into the relationship between sensory information and social behaviors may help scientists enhance their understanding and treatment of neuropsychiatric and neurodevelopmental disorders.
“By comprehending and modeling how multisensory cues are integrated into social behaviors, we can pave the way for future studies in other species and potentially identify specific treatment targets,” Schretter remarks.
Concentrating on combative flies
The researchers previously pinpointed a cluster of neurons that trigger aggression in female fruit flies, prompting them to engage in fights. They also found that these neurons intersect with pathways responsible for processing visual information. This laid a solid foundation for scientists to employ the connectome to investigate the precise neurons and circuits the fly’s brain engages to modify its visual focus according to its needs.
Similar to how we need to concentrate on nearby vehicles rather than the surroundings while driving on a busy road, female fruit flies in an aggressive state must direct their attention to the fly they’re about to confront instead of searching for food.
Utilizing the fruit fly connectome created by Janelia researchers and collaborators, the team identified how the aggression-promoting neurons link to those that manage visual input. This indicates that aggression neurons are regulating the flow of visual data, allowing the fly to concentrate on essential stimuli.
With this insight, the researchers employed genetically modified fruit flies crafted by Rubin and others at Janelia to manipulate various neurons by switching them on or off to further investigate this regulation process.
The findings revealed that the aggression neurons operate through three distinct mechanisms to manage vision. One circuit comprises excitatory inputs that combine specific visual traits with the fly’s internal status. Another circuit adjusts the information coming from the fly’s optic lobe, while a third acts as a toggle switch, enhancing the visual transmission of one group of neurons while reducing it from another.
These diverse circuit mechanisms give the fly the adaptability to modulate its attention toward different aspects of its visual surroundings according to the context. Furthermore, the researchers discovered that similar circuits function in male fruit flies during courtship, implying that various social behaviors might utilize shared circuit mechanisms.
Besides offering insights into how aggression influences vision, this new study establishes a framework for utilizing the connectome to identify the neurons and circuits linked to social behaviors—data that would have been challenging to obtain without this neural blueprint.
For Schretter, this research marks a starting point for investigating how external factors influence behavior.
“For me, as someone focused on behavior, the core questions I had at the start of my PhD and postdoc—regarding how sensory data and internal influences govern behavior—can now be explored in unprecedented detail,” Schretter says. “We now possess the tools to examine these issues with remarkable precision.”
For Rubin, the new findings provide a sense of completion. Having witnessed firsthand the effectiveness of the tools he developed, he’s now ready to shift his focus to other research endeavors.
“It illustrates that individuals can engage in similar work for entirely different reasons, leading to distinct outcomes and future directions,” Rubin states.
