午夜剧场

Biologically speaking, vision can be defined as "light information captured by receptors in the retina through the eyeball, transmitted to the visual cortex of the cerebrum, and perceived." If there are no problems in the pathway from the eyeball to the optic nerve and then to the primary visual cortex in the occipital lobe, one can "see" things normally. However, the processing of visual information does not end at the primary visual cortex. It is said that among the visual information reaching the primary visual cortex, information such as shape, color, and size is processed in the lower part of the brain (ventral stream), while information such as position and movement is processed in the upper part of the brain (dorsal stream).

When the cerebrum is damaged due to a stroke or other causes, various visual cognitive impairments occur depending on the site of the damage. If damage occurs in the ventral visual processing pathway, visual agnosia occurs, where the shape and color of objects cannot be recognized. Furthermore, if the primary visual cortex is damaged, one cannot see objects, which is called cortical blindness. Patients with visual agnosia or cortical blindness complain that they "cannot see," but they may still be able to avoid obstacles while walking or catch a ball. This phenomenon is called blindsight. Patients with blindsight "cannot see" but can "feel" that something is there and move accordingly. Conversely, if the dorsal part of the brain is damaged, a symptom called optic ataxia occurs, where the patient can "see" the object but cannot reach out and grab it.

Looking back at the retina, photoreceptor cells are concentrated in a central area called the macula, and when focusing on an object, light is gathered in the fovea at its very center. Seeing things with the fovea is called central vision, and everything else is called peripheral vision. Information from central vision is processed in the ventral stream of the cerebrum, while information from peripheral vision is processed in the dorsal stream. Since part of the peripheral vision-dorsal information is sent directly to the motor cortex, one can "feel" and move before "seeing." It is thought that professional baseball players are able to hit a 150 km/h breaking ball by utilizing information from peripheral vision. Perhaps at the master level, one can even "see" peripheral vision information as a visual image. Saying "the ball looks like it's standing still" might be an example of that. When I was playing youth baseball, my father, who was the coach, used to tell me to "keep your eyes on the ball and hit it," but since I was naturally unathletic, the ball would already be in the catcher's mitt while I was trying to see it with my central vision.

Thinking about such things while watching Shohei Ohtani's performance with a beer in hand has become my favorite way to relax lately.