1/4 Hour Neuro #44: "How to Optimize Proprioception Work?"

Introduction: Beyond Classic Proprioception

Welcome to this episode of "1/4 Hour Neuro" where we delve deep into proprioception. Often reduced to mere mobility or the activation of mechanoreceptors, proprioception is actually a complex sensory system that is fundamental to our body and brain. We will uncover the multiple facets of this internal sense, the various receptors involved, and the implications of its proper functioning on our movement, learning, and even our social interactions.

Proprioception is one of the three sensory information systems, alongside interoception (internal environment) and exteroception (external environment). It can be defined as a "3D interview" of our body in space and time, a constant mapping of our position and movements. Contrary to popular belief, proprioception is processed in the brain and not directly in the joints or muscles.

The Different Categories of Proprioceptive Receptors

Proprioception is not limited to just mechanoreceptors, which are often highlighted in gyms. Many other types of receptors play a crucial role in this information gathering:

Mechanoreceptors and Their Specificities

• Nociceptors and Chemoreceptors: Related to threats and danger, or chemical exchanges.
• Mechanoreceptors: The ones we know best, associated with mechanical tension. Among them, we distinguish neuromuscular bundles, responsible for the sensation of muscle stretching with a fast conduction speed, and Golgi organs, related to tension and muscle contraction, with a slower conduction speed.
• Baroreceptors: Sensitive to pressure.
• Electromagnetic Receptors: Associated with magnetic fields and light.

Each of these receptors must provide accurate and precise information. If one of them is faulty, it can lead to misinterpretation by the brain, incorrect decision-making, and ultimately, inappropriate or even dangerous movement.

Other receptors, such as Merkel discs, which are sensitive to pressure, or those related to skin twisting, are also essential for complete proprioception. The goal is to work on all these receptors to improve movement and performance.

Proprioception: A Brain Process and Its Implications

It is crucial to understand that proprioception is processed in the brain. Joints and muscles are merely sensors that send information. The brain then integrates this data to make decisions, forming the basis of our motor actions.

Focusing solely on balance on an unstable board, for example, is a very limited approach to proprioception. Methods such as applying a cold pack, which stimulates thermoreceptors, or focusing on the maximum contraction of a muscle ("mind-muscle connection") can be more relevant ways to work on proprioception by stimulating other receptors.

Observing Proprioception in Daily Life

To assess whether your proprioception is well-developed, ask yourself these simple questions:

• Do you need to look at what you are grasping to bring an object to your mouth, like a coffee cup?
• Do you look at your feet while walking?
• Can you focus on the muscle you want to work during exercise without looking in a mirror?

If the answer is yes to these questions, it is possible that your proprioception needs refinement. Looking in a mirror while squatting, for instance, can skew movement by relying on vision at the expense of internal sensation. It is important to allow the body to feel the movement without visual aid.

The Crucial Influence of Primitive Reflexes

Primitive reflexes are automatic movements developed in utero and during early childhood. They form the basis of proprioceptive development. The proprioceptive system begins to develop very early, even in the mother's womb. The baby's movements in amniotic fluid and pressure variations on its developing skin contribute to this early development.

Poor integration of primitive reflexes can lead to proprioceptive hypersensitivities or hyposensitivities. These can have significant repercussions, including academic difficulties (reading, information processing), social problems (aggressiveness, hyperactivity), and a lack of motor coordination.

Proprioception and Cognitive Functions

Studies, such as that by Matchin and St. Mihiel (2016) on reading, have demonstrated the influence of proprioception on reading speed, pupillary response, and micro-eye oscillations. Good proprioceptive processing is therefore essential for cognitive performance, requiring rapid information processing in both children and adults.

Proprioception also plays a key role in motor strategies. For example, the asymmetrical tonic neck reflex is one of the first proprioceptive manifestations in infants and is fundamental for coordination. Difficulty performing contralateral movements (right arm with left leg) or observing someone who constantly looks at their feet while walking are signs of proprioceptive deficits.

The Oral Sphere and Proprioception

Work on the oral sphere can have a significant impact on overall stability and proprioception. This demonstrates that proprioception is a complex system that sometimes requires working on adjacent parameters to optimize its functioning. A holistic approach is, therefore, essential.

Conclusion: Isometric Integration for Optimal Proprioception

It is crucial to stimulate your central nervous system to optimize proprioception. Isometric integration, where pressure is applied to the body, is an excellent method. It directly works on the sensation of tension and position, and regulates essential reflexes like the asymmetrical tonic neck reflex.

In summary, proprioception goes well beyond balancing on one leg. It is a rich and complex sensory system involving multiple receptors, essential for our movements, cognition, and overall well-being.