Researchers identify areas of the brain that control the ability to perform complex, continuous movements

Johns Hopkins scientists interact to control their ability to perform complex behaviors in a new series of experiments with mice trained to perform a series of movements and momentarily “change course”. It reports that it has identified an area of ​​the animal’s brain. To help the mouse rebound when continuous movement, and mouse movement is interrupted without warning.

According to them, the study could one day help scientists find ways to target these areas of people and restore motor function caused by injuries and illnesses.

The results of the Johns Hopkins-led experiment were published on March 9th. Nature..

Based on specially trained rodent brain activity measurements, researchers have discovered that three major areas of the cortex have different roles in how mice navigate a series of movements. Did: premotor cortex, primary motor cortex, and primary somatosensory cortex. Everything is at the top of the mammalian brain and is basically the same in people.

The team is involved in the primary motor cortex and primary somatosensory cortex controlling the immediate movement of the mouse in real time, while the premotor cortex is the entire planned sequence of movements and how the mouse responds. The sequence is unexpectedly interrupted, concluding that it seems to be controlling what to adjust.

When animals make continuous movements, researchers have found that the premotor cortex may send electrical signals to two other sensorimotor cortical areas via special neurons, between cortical layers and in cortical layers. Further research is planned to graph the path of those signals between.

Whether you’re an Olympic athlete practicing downhill slopes or a person doing daily chores such as driving, many tasks involve a series of learned movements that are repeated over and over again. increase. “

Dr. Daniel O’Connor, Associate Professor of Neuroscience, Johns Hopkins University School of Medicine

O’Connor led the research team. Such continuous movements may seem obvious and simple, but they involve complex organization and control in the brain, and the brain not only correctly directs each movement, but also links them together. It needs to be organized throughout the movements that have been made.

O’Connor says that if something unexpected happens and interrupts an ongoing sequence, the brain needs to adapt and instruct the body to reconstruct the sequence in real time. Failure of this process can result in disasters such as falls and car accidents.

Neuroscientists have long studied how mammals compensate when individual movements are interrupted, such as reaching for a coffee cup, but new research is a complex of some movements. Compensates for unexpected events designed to address the challenge of tracking what happens when a sequence needs to be reorganized in real time.

For example, in the case of an Olympic skier, the skier expects to approach the gate along the downhill and perform a series of movements planned to pass through the gate, but obstacles disturb the skier’s trajectory and the course. ..

“It remains largely a mystery how the mammalian brain can take sensory cues and use them almost instantly to completely switch from a series of ongoing movements to another. O’Connor, in collaboration with former graduate students in O’Connor’s lab, Duo Xu, Ph.D., designed a series of experiments in mice to track the brain regions that process the “course change” queue. bottom.

For research, researchers first created a “course” for mice trained to stick out their tongue and touch a “port” (metal tube). When the researchers moved the harbor, the mice learned to touch the harbor again. During the course, mice that touched the harbor with their tongue received a reward when the harbor moved to its final location. All of this training was aimed at simulating a series of expected repeated learned movements, similar to a skier’s downhill run.

To study how unexpected clues can encourage the brain to divert, researchers have forced mice to perform what scientists call “backtrack trials.” Instead of moving the port to the next location, the researchers moved the port to the previous location, so when the mouse stretched its tongue, it couldn’t find it, and the course was reversed to find it. Let’s advance the course and get a snack.

“Each sequence of portricks contains a series of complex movements that the mouse brain needs to perform correctly in an exercise plan, but quickly re-dos when it turns out that there is no expected port. We also need to organize, “says O’Connor.

During the experiment, researchers used brain electrodes to track and record electrical signals between neurons in the sensorimotor cortex that control overall movement. Increased electrical activity corresponds to increased brain activity. Because many areas of the cortex can be activated when mice move through the course of the experiment, researchers have been genetically engineered to be able to selectively “silence” or deactivate specific parts of the cortex. We used mice bred with brain cells. Therefore, scientists can narrow down the location of areas of the brain that are directly involved in movement.

“The results provide a new picture of how the hierarchies between neural networks of the sensorimotor cortex manage continuous movement,” says O’Connor. “The more we learn about these interacting neural networks, the better we are in understanding human sensorimotor dysfunction and how to fix it.”https://www.hopkinsmedicine.org/ “>