Brain Science (Neuroscience) is one of the foundation sciences for applying occupational therapy in various populations; learning disabilities, mental health conditions, stroke and head injuries. Sensory Processing is a term used in multiple ways, but for this article it is for explaining some of the science and application of the nervous system.
The Science of Sensory Processing
The science of sensory processing is embedded in neuroscience. We understand by neuroimaging how neurons (brain cells) form pathways that are organized for our sensory motor response system. We know for instance that airwaves are first registered by the tympanic membrane. The vibration is then mechanically transferred to hair cells that register the details of sound in our cochlea. This becomes neuro-information via the vestibular cochlear nerve and integrates with virtually all of the other sensory systems we are processing, including vision and space. The vast array of brain cells involved in integrating this information allow us to create a meaningful awareness of sound and respond to it appropriately. We know where it is coming from, what it is and if we need to pay attention to it. Most importantly we know which way to move away from it if we sense danger, and which way to move toward it if we want or need it.
The Vestibular System
My drawing from a scientific illustration course, while in my studies at CSU Fort Collins. The source drawing looks very close to this, and I can not recall it. Help please.
Balance, Body Position and Motor Planning, The Vestibular System
Vestibular sensation is registered or detected in our inner ear in a structure called the semi-circular canals or the labyrinth. In combination with detecting our movement we also sense the downward pull of gravity with our vestibular receptors in the inner ear. The vestibular system is often referred to as our sense of balance, but in fact in contributes to many brain functions related to reading and writing. Occupational therapists take advantage of this sensory system to enrich a sense of timing, sequencing, directionality and integration functions.
Balance is obtained through two powerful sensory systems working together. We have a strong awareness of our body position through muscle sensory receptors in each muscle. This system is called the proprioceptive system. The vestibular system and the proprioceptive system coordinate, or integrate, their information and this allows us to stand up easily without falling over. We are not consciously aware of vestibular/proprioceptive integration, unless we loose it by some injury or accident. Then we have to consciously use our vision or our other senses to tell us where we are in relationship to other objects and people.
Our vestibular/proprioception provide a motor planning blueprint of where we are and what position we are in. We can close our eyes and know if we are sitting down or standing up, and what position all of our limbs are in. In order to coordinate our muscles for some purposeful event, we need to understand what direction we are going to move, how fast and how to grade the movement so that we have the just right slowing-down actions too. When we have a strong physical sense of self, we know where we are in relationship to other things and people. This helps us unconsciously coordinate how to move in and around objects and people in order to obtain what we want or in some cases, get away from what we do not want.
Integrative Function
The integrative nature of the vestibular system is quite strong. Research confirms that there is a motor component to learning. If we use our motor system during a learning task, we probably will have more memory recall of what we have learned. The vestibular system has it’s home base in our cerebellum, and the cerebellum has a large role in motor planning. From the cerebellum, the vestibular system branches out to almost all areas of our brain. It is a widely distributed system, so just about every other sensory system coordinates with the information provided by the vestibular system. The cerebellum is often called the motor brain. It helps establish basic motor planning strategies, so that we don’t have to consciously coordinate every minute muscle movement. The cerebellum may even provide more conscious thought than we at first thought.
Awake/Alert/Arousal State
The vestibular system contributes to our awake and alert state for learning. When we roll out of bed in the morning, our head position actually wakes us up! All of the muscles along the spine, head and neck begin to work together to get us up and going in an alert, or as alert as we can get, state for our day. Students who have a low functioning vestibular system often need more movement to stay alert and orient to the teacher with their eyes and their ears. They can be found propping their elbows on the desk and cradling their heads. Often they simple lay their heads down and opt out of the learning task. The vestibular system sets our muscle tone. Muscle tone is our individual physical muscle readiness for any voluntary movement. We can be tightly wired and ready to spring into action, or so sluggish that we slump into our seat and practically melt into the chair. A tightly wired student may be hyperactive, and a lower tone student may have to work much harder to get started when asked to write or read. A healthy vestibular system sets up a just right alert/arousal state for learning, and keeps our bodies in a learning state, both physically and mentally
