Neuron Exhibits Two Distinct Behaviors
In a groundbreaking study published recently in Current Biology, researchers from Yale University have uncovered an intriguing aspect of the fruit fly's olfactory system. The research reveals that a single neuron in fruit flies can control two distinct behaviours in response to the same smell, particularly the smell of rotting fruit.
The olfactory neuron in question sends divergent signals to downstream neurons, enabling the flies to both move towards the source of the smell and adjust their walking speed. This discovery challenges the long-held idea of neural specificity, which posits that each neuron serves a single purpose.
The study focuses on two types of third-order neurons, lateral horn neuron 1 (LHN1) and lateral horn neuron 2 (LHN2). The LHN2 brain pathway appears to be responsible for a fruit fly speeding up when they get closer to their target, while LHN1 maintains a steady electrical current in response to the smell of ethyl acetate, a chemical signal of rotting fruit.
The distinct odor-coding dynamics originate from differences in the dynamics of PN synapses targeting each lateral horn neuron type. Transient lateral horn neurons make corresponding transient contributions to behavioural odor attraction in walking flies, whereas sustained lateral horn neurons may make sustained, but nuanced, contributions.
Interestingly, fruit flies with a disabled LHN2 don't pick up the pace when the smell of rotting fruit gets more intense, suggesting that this neuron plays a crucial role in regulating speed. Conversely, flies with a disabled LHN1 still move towards the source of the smell but stop moving when the concentration of the odor dips, indicating that this neuron is instrumental in guiding direction.
The findings could help unravel how neural circuits encode complex behaviours efficiently, adding to the growing body of evidence that multifunctional neurons exist in various species, including crayfish, roundworms, mice, and humans. This research offers a fascinating insight into the intricate workings of the brain and opens up new avenues for further study.
The groundbreaking study on the fruit fly's olfactory system in Current Biology suggests that multifunctional neurons may exist across various species, such as mice and humans, due to a single neuron controlling two distinct behaviors in response to the same smell. This finding challenges the traditional neural specificity theory, as one neuron, the LHN1, is shown to maintain a steady electrical current in response to the smell of ethyl acetate, a signal of rotting fruit, while also guiding direction. Meanwhile, another neuron, LHN2, is instrumental in regulating speed, especially when flies approach the target more closely. These discoveries in neuroscience news may pave the way for understanding how the brain efficiently encodes complex behaviors, potentially contributing to the treatment of medical conditions like depression, where speed and direction may play a crucial role.
