Tara Kachroo

The primacy of vision

The primacy of vision

Vision rules

In 1991 Felleman and Essan published a study called “Distributed Hierarchical Processing in the Primate Cerebral Cortex”. This article scientifically established the centrality of the visual system in primates.

The retina is an outgrowth of the brain. It contains 150 million light-sensitive rod and cone cells. It’s damn sensitive and incredibly important. Neurons devoted to visual processing in the brain are in the hundreds of millions. They take up about 30% of the cortex. Touch takes up just 8%, and hearing 3%. The visual system has “extensive connections with cortical areas outside the visual system proper, including the somatosensory cortex, as well as neocortical, transitional, and archicortical regions in the temporal and frontal lobes.”

But we all kinda know vision rules already. Our language reflects how central our way of thinking, feeling and being in the world vision is. Do you “see” what I mean?

 

The primacy of vision


Eye muscles coordinate with the rest of the body

There are so many factors in our ability to see and to see well. In my work, I analyse eye movement as part of integrated neuromotor functioning and so I focus primarily on how the 6 extraocular muscles coordinate with the rest of the body’s motor control system. The coordination of eye movements with several neck muscles, such as the SCM and suboccipitals, is well established, but these coordination patterns go much farther and deeper than just the neck as the body moves as a whole, never in parts. For example, the inability to look straight up or straight down can affect the functioning of the entire posterior and anterior kinetic chain and affect one’s ability to forward fold, back bend and/or balance. In particular, our ability to focus our eyes is connected to posterior chain function, as they develop at the same time, around 4 months of age, when babies start really holding up their own heads while on their bellies and looking around at things. The same is true with other eye movements and other primary ways that our bodies coordinate to move through space and function in the world.

However, despite the need for coordination between the eyes and the rest of the body, dissociation of the two movement systems is just as important. Dissociating eye movements from other body movements are often an important part of whiplash and concussion rehab.

Seeing keeps us Safe

Muscular function is a slave to the body’s ability to feel safe. Since vision is so important to our ability to stay safe in the world, and such a large part of our brain’s functioning, its supremacy is powerful. So, if you can’t look down, you probably shouldn’t bend down, and your motor cortex will keep you from doing so.

What I’ve found is that it’s not just people with a history of concussion that have eye movement issues. A variety of types of trauma and chronic stress can cause problems. I’ve been continuing my study of ocular motor assessment recently, but I’m just at the beginning of my journey. Despite the novice nature of my exams, Integrative Movement Therapy oculomotor assessments do include things that you won’t get at a vision center, such as assessment of specific full-body kinetic chains in response to eye movement deficiencies and rehab exercises that address these.