Salk researchers isolate specific neurons controlling complex social behaviors

Our brains constantly integrate information about both our internal state and our surroundings to determine how we behave. Much of this coordination depends on neuromodulators-chemical messengers that establish how neurons communicate and function. Understanding how these signals produce distinct responses to different social contexts is crucial to understanding how the brain works.

Remarkably, many of these fundamental molecular mechanisms are conserved across evolution, including in the tiny brain of a fruit fly. That makes fruit flies powerful models to study how neuromodulators influence complex social behaviors such as aggression. One such neuromodulator, octopamine-the functional counterpart of noradrenaline in humans-can regulate a wide range of processes, from aggression and feeding to wakefulness and memory.

Scientists have long suspected that a different set of neurons using the same neuromodulator may be specialized to a specific process, but they lacked the tools to study them separately. As Valentina Fajner, PhD, the co-first author of the study and staff scientist at Salk, describes, "It's like trying to isolate a single instrument within an orchestra."

Now, Salk researchers have developed a genetic toolkit that allows them to do just that. The study, published in Current Biology on August 27, 2026, shows that distinct neuronal subtypes, identified using the genetic toolkit, can produce different-and even opposing-effects, including pinpointing neurons that suppress aggression.