The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) was established by President John F. Kennedy, with the support of Congress, in 1962 to study the complex process of human development from conception to old age. Part of its mission is developing medical rehabilitation interventions to improve the health and well-being of people with disabilities. R. Douglas Fields, Ph.D., is Chief of the Nervous System Development and Plasticity Section at NICHD.
Dr. Fields was the lead presenter at a Joint ARVO/AAO Symposium entitled Visual Neural Plasticity: Cells to Systems, at the American Academy of Optometry in October 2015 in New Orleans, sponsored by the Section on Binocular Vision, Perception, & Pediatric Optometry of the AAO.
His latest work centers on activity-dependent myelination as a new mechanism of nervous system plasticity. I wasn’t able to attend the meeting, and imagine that this was a stimulating symposium. I picked up a copy of Dr. Fields’ latest book on Friday, and he continues to live a parallel life simultaneously conducting research while writing for public consumption. His latest book is Why We Snap, and Chapter 7 is an intriguing one entitled “Extrasensory Perception?” in which Fields takes us on a Magical Mystery Tour of dermo-optical perception (DOP).
DOP is a controversial concept that has been around for centuries in various iterations, claiming in short that the blind can gain some sense of sight through skin, and the possibility of blind vision is gaining more cachet through neuroscience. Fields introduces the topic gingerly, first beginning with the more traditional element of blindsight, in which subconscious seeing can occur through a blind portion of the visual field particularly via a route that goes straight from the eye to the amygdala when the stimulus is one vested with emotion.
Fields then introduces us to Tricia, a legally blind graduate student at Berkeley who has NLP in both eyes but is working on her sense of vision through DOP, accentuated by cannabis. Fields does a masterful job relating what Tricia’s MRIs look like when she feels images (her whole brain lights up) compared to when she looks at them (only baseline activity), and Tricia demonstrates how cannabis lights up her DOP. (My mentor and friend, Dr. Jack Richman continues to be at the forefront of cannabis considerations in eye care.)
Marijuana helps Tricia access her form of vision, but is impractical to use on a regular basis for her desired purposes. For that she awaits some form of neuroprosthetic, and the rehabilitation to help her learn how to see using eye movements to map out visual space.
From Chapter 7:
“Certain strains of marijuana just don’t work,” she said. “Different strains actually affect different aspects of vision. So I can have one strain that my color perception increases, and I can have another strain in which my motion perception and contrast perception increases, and rarely do I get both at the same time. She set the vaporizer on the kitchen counter across from me, turned it on, and inhaled the vapor through a clear tube. She held the smoke in her lungs and then exhaled … Chills and goose bumps flahsed over my skin as I saw a veil of blindness being to lift … I began to realize that what she was perceiving is a sense of depth — three-dimensional visual space — as her eyes focus on nearby and then distant objects. This is something that is beyond the reach of two -dimensional tactile sensation … She turned to face me. For the first time all afternoon, her two brown eyes looked at me straight in the eye. It was as if I were seeing her face or the first time. “Essentially what I want, Doug, if anyone can make this happen, is for someone to teach me how to see. Because it is really frustrating for me to figure it out by myself.”
… All of the aspects of vision that we take for granted took us years of experience from infancy to sculpt our visual cortex until we could see objects, track them, distinguish foreground from background, identify colors, and all the rest that we are now able to do completely automatically, but Tricia is working this all out from first principles to make sense of it. She is building bridges over the Mississippi. Another important thing that Tricia’s experience reveals is that many of the photoreceptors in our retina have little to do with what we normally think of as vision. They do not form images … All of this detection and rapid eye movement toward the “unseen” but clearly perceived visual stimulus is automated and unconscious. Some of these photoreceptors have survived in Tricia’s retina and, under the influence of cannabis, they have become more sensitive to light.