Educators, neuropsychologists, and other professionals recognize that difficulties with executive functioning impact not only a child’s learning, but all aspects of life. There are three main areas of executive function: working memory, flexible thinking, and inhibitory control (which includes self-control). Working memory is the ability to keep things in mind so that you can put them to use. Flexible thinking is the ability to see problems from multiple angles and find different ways to solve them. Self-control is the ability to stop before you respond on impulse; to control your attention and your behavior; and to manage your emotions. It is not surprising therefore that children who struggle with executive function often have trouble paying attention and focusing; organizing and planning; starting and completing tasks; and shifting focus from one task to another. An excellent background on executive function and its disorders is provided in this YouTube video by Dr. Stephanie Carlson.
It may not seem obvious, on the surface, that there is any interaction between the visual system and executive function. After all, standard depiction of the brain shows that executive function is localized to the frontal lobe whereas vision occurs in the occipital lobe, way in the back of the brain.
But as many of you know by now, contemporary neuroscience takes a dim view of limiting vision to the occipital lobe. We laid the groundwork for this in a blog last August called The Biological Mind’s Eye.
There is a nice, concise volume on the clinical applications of Ocular and Visual Physiology authored by Dr. Simon Skalicky with a chapter on The Neural Control of Eye Movements that helps make this point clear regarding the hierarchy of oculomotor control.
What enables us to move our eyes? On the surface it appears that the six pairs of muscles executes movement up, down, to the side, obliquely, and to converge. But the muscles are only able to move to the extent that proper messages come through the cranial nerves of the brain into a final common pathway for eye movement control. These messages are gated through the premotor nuclei in the brainstem gaze centers that orchestrate the direction, speed, and duration of eye movements. But eyes don’t move in isolation, and subcortical integration contributes to the neural code for control through the superior colliculus in planning and maintenance and the cerebellum for fine tuning and long-term adaptation.
Ah, but as my friend Bob Sanet would say, who talks to the neurology of eye movements? It turns out that is the intimate conversation occurring between the frontal lobe, the occipital lobe, and the substrates of their communication network. Frontal and supplementary eye fields in the frontal lobe link with extrastriate and parietal cortex in the generation and planning of ocular movements as well as the integration of movement planning with 3-D spatial maps constructed from visual sensory information.
For an in-depth review of the interaction between executive function and eye movements, see Frontal eye field, where art thou? Anatomy, function, and non-invasive manipulation of frontal regions involved in eye movements and associated cognitive operations, published in Frontiers in Integrative Neuroscience. An equally exciting paper in Frontiers was authored the same year by our colleague Dr. Tara Alvarez from the New Jersey Institute of Technology. Originally pairing with Dr. Vince Vicci, Dr. Alvarez has more recently collaborated with Dr. Mitch Scheiman in exploring the whole-brain implications of convergence insufficiency (Dr. Alvarez and Dr. Scheiman will be speaking at the COVD meeting in Toronto in 2020). Have a look at the paper by Alvarez and colleagues: Functional activity within the frontal eye fields, posterior parietal cortex, and cerebellar vermis significantly correlates to symmetrical vergence peak velocity: an ROI-based, fMRI study of vergence training.
Now go back to the opening of this blog, and the essential challenges for children who struggle with executive function in paying attention and focusing; organizing and planning; starting and completing tasks; and shifting focus from one task to another. Can you envision how lenses, prisms, and active vision therapy set the stage for improving executive function?