Researchers at Champalimaud Foundation in Portugal Introduce a Bi-Directional Neural Network that gets Visual and Motor Circuits in Sync

This Article Is Based On The Research Paper 'Walking strides direct rapid and flexible recruitment of visual circuits for course control in Drosophila'. All Credit For This Research Goes To The Researchers 👏👏👏

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The central nervous system in humans makes them capable of adapting to new environments and scenarios. These reactions result from past experiences, physiological needs, and sometimes body instinct.

The signals linked with behavioral goals and the current bodily condition are called motor context in human bodies. The vision and action are very important in this context. Their reliance may appear unconnected, yet they are crucial in directing movement in terms of motor context. Choose a location on the wall and try placing your finger on it with your eyes closed to see how closely the two are related.

The strange behavior of visual neurons has grabbed neuroscientists’ interest following a recent event involving fruit flies. A fruit fly was recently seen walking on a floating 3D treadmill made of a little styrofoam ball. Even though the room is pitch black, an electrode recording visual neurons in the fly’s brain transmits a strange stream of neural activity that rises and falls like a sinusoidal wave. 

Researchers from the Champalimaud Foundation in Portugal dug deep into this exceptional finding, leading to a groundbreaking discovery. The team claims that their motivation sprang from the fact that because of the darkness of the environment, there was no visual signal available to activate the neurons in that manner while recording visual neurons. This led them to believe that the strange activity was either an artifact, which was implausible, or originating from an unseen source. 

After years of research, the researchers reveal their findings in their paper “Neuron: a bi-directional neural network connecting the legs and the visual system to shape walking.” One of the most surprising characteristics of this discovery is that it allows for simultaneous walking on two different timelines. It works quickly to monitor and correct each step while supporting the animal’s behavioral aim.

The researchers focused on a specific type of visual neuron that has been linked to motor parts of the brain. They aimed to identify what signals these neurons receive and whether or not they have a role in the movement. The researchers employed a sophisticated technology known as whole-cell patch recording to answer these questions, which allowed them to get into the neurons’ “mood,” which can be positive or negative.

Electric currents change the total charge of the receiving neuron as neurons communicate with each other. When a neuron’s net charge is higher, it’s more likely to activate and send signals to other neurons. The neuron is more inhibited if the charge is negative.

The researchers studied the charge of the neurons and discovered that it was perfectly synced to the animal’s steps for fine-tuning each action. The neuron was more positive while the foot was up in the air, according to the researchers, and was ready to send out adjustment directions to the motor region if necessary. The charge was more negative while the foot was on the ground, making modifications impossible, thus blocking the neuron.

When the researchers looked into their findings further, they discovered that the charge of the neurons was also shifting over time. Particularly when the fly was walking quickly, the charge grew increasingly positive. According to the researchers, this variety helps the animal retain its behavioral aim. They went on to say that the longer the fly has been walking fast, the more likely it is to need assistance to keep up with its plan. As a result, the neurons become more “alert” and ready to be recruited for movement control.

The researchers carried out numerous studies to better understand its direct involvement in walking. It not only reveals a new visual-motor circuit but also offers new insight into the neurological mechanics of movement.

Exploration, navigation, and spatial perception are all behaviors that many animals, including humans, rely on speed-related representations for. The present model of behavior formation is very ‘top-down,’ with the brain controlling the body. In contrast, the paper’s findings show how signals from the body play a role in movement regulation. Though they discovered similar pathways in the fly animal model, they believe they exist in other creatures.

Source: https://www.eurekalert.org/news-releases/951864

Paper: https://www.cell.com/neuron/pdf/S0896-6273(22)00347-6.pdf