Genetically engineered flies reveal brain's braking secrets

Researchers in Florida have deciphered the intricate neuronal mechanisms involved in stopping. Their results reveal how the brain utilizes different neuronal mechanisms depending on the environmental context.

As reported on the Spider's Web portal, this discovery is fascinating in its own right, but the true marvel lies in what was happening within the brains of these tiny creatures.

The Florida researchers genetically engineered fruit flies to respond to red light, akin to how a driver reacts to a traffic signal. When a light beam struck their eyes, the insects immediately ceased movement.

Stopping is essential for nearly all animal behaviours; it's a "critical" action. During foraging, when an animal detects food, it must stop, or when it's dirty, it must pause to clean itself. The capacity to stop appears straightforward. However, until now, scientists have not fully understood this mechanism due to its complex interactions with competing behaviours such as walking.

- Purposeful movement through the world relies on halting at the correct time as much as walking. It is central to essential behaviours like eating, mating, and avoiding harm. We were interested in understanding how the brain controls halting and where halting signals override signals for walking - says Dr. Salil Bidaye from the Institute.

They harnessed the simplicity of the fruit fly, which has a streamlined nervous system and a brief lifespan. Bidaye and his team pinpointed the neurons responsible for initiating stopping.

By using optogenetics, they activated specific neurons by directing red light at them. This allowed them to determine which neurons stopped the freely walking flies.

The scientists identified three distinct types of neurons, dubbed Foxglove, Bluebell, and Brake, that caused the flies to stop when activated.

The first two neurons contributed to what they referred to as the "Walk-OFF" action, while the third neuron was responsible for the "Brake" action (disabling walking and activating braking).

The "Walk-OFF" mechanism functions by disabling the neurons that facilitate walking, much like lifting one's foot off the gas pedal in a car.

The "brake" mechanism actively inhibits stepping by increasing knee joint resistance and promoting postural stability. It further inhibits the neurons that support walking, effectively preventing steps.

The discovery by Florida scientists might eventually aid in treating neurodegenerative diseases like Parkinson's by precisely manipulating specific neuronal activities.

Critics who approach science cautiously worry that with such discoveries, we may soon move from mere observation to actively influencing our thoughts and actions.