Sixth sense genes

Sight, hearing, smell, taste and touch: we are all familiar with the five senses that allow us to experience our surroundings. but meEqually important, though less well-known, is our sixth sense: “Its function is to collect information from muscles and joints about our movements, posture, and position in space, and then transmit it to our central nervous system,” explains Dr. Niccolo Zampieri, Head of the Laboratory for the Development and Function of Neural Circuits at the Max Delbrück Center in Berlin. This meaning, known as proprioceptionIt is what allows the central nervous system to send the correct signals through the motor neurons to the muscles so that we can perform a specific movement.”

So, this sixth sense, Unlike the other five, he is completely unconscious, It is what keeps us from falling into the dark or allows us to bring a cup of coffee to our mouth with our eyes closed in the morning. But that’s not all: “People who do not have proprioception cannot perform truly coordinated movements,” continues Zamperi, leader of Titled article team Molecular identity of receptor subtypes that innervate different muscle groups in mice It was recently published in Nature Communications. In it, the authors describe the molecular markers of the cells involved in this sixth sense; Some The results should help researchers better understand how it works proprioceptive sensory neurons (pSN).

The importance of good communication

proprioceptive sensory neurons They are found in the dorsal root ganglia of the spinal cord. They are connected via long nerve fibers to muscle spindles and Golgi tendon organs, which Continuously record the stretching and tension of every muscle in the body. These are excitatory sensory neurons They are responsible for sending this information to the central nervous system, which is responsible for controlling the activity of motor neurons so that we can make movements.

Dr. explains. Stefan DietrichZampieri Lab member. “However, until now we knew very little about the molecular programs that enable these subtle connections and give each muscle’s sensory neuron its unique identity.”

“This is why in our study we looked for molecular markers that distinguish excitatory neurons of different muscles in the body of mice: abdomen, back or limbs,” adds Dietrich, lead author of the study.

So the team studied which genes in proprioceptive sensory neurons in the abdominal, back and leg muscles translate to RNA, and they found that different genes are associated with each muscle group.” We also show that these genes are already active in the embryonic stage and remain active for at least some time after birth. .” Dietrich, who also explained that this means that there are specific genetic programs that decide whether a primary receptor will innervate the muscles of the abdomen, back, or limbs.

Among their findings, the Berlin researchers identified several genes for Afreen and its receptors. “We know that these proteins are involved in directing emerging nerve fibers towards their target during the development of the nervous system,” explains the researcher.

Towards prosthetics connected to the nervous system

“The markers we have identified should help us further investigate the development and function of muscle-specific sensory networks,” Dietrich explains. For example, cOn the OptogeneticsWe can use light to activate and deactivate motor receptors, either individually or in groups. This will allow us to reveal their specific role in the sixth sense,” Zamperi adds.

This knowledge could in the near future benefit, for example, patients with spinal cord injuries. “Once we better understand the details of proprioception, we will be able to improved neuroprosthesis design, that takes over motor or sensory abilities that have been affected by an injury.”

Among the team’s other recent discoveries about proprioception is that it’s also central to the development of a healthy skeletal system. theScoliosis, for example, is a condition that sometimes develops during childhood development and causes the spine to twist and curve. “We suspect this is due to proprioceptive dysfunction, which alters muscle tension in the back and deforms the spine,” Zampieri says.

Hip dysplasia, which is a malfunction of the hip joint, can be caused by a defect in proprioception. This has led Zamperi to imagine another outcome of the research: “If we could better understand our sixth sense, it would be possible to develop new therapies that effectively counteract these and other types of structural damage,” he concludes.