We remember many things from decades past. Some in such vivid detail, it’s tempting to think as if a movie camera had been rolling a long strip of cellophane quickly from one side of a dark cavity to the other, as a shutter between the two sides winking open and shut, sixty times a second. With each wink, a little beam of light from the outside world streams in and knocks some electrons loose, thus changing the reactivity of the chemical gunk stuck to the roll of cellophane. All of those moving parts have now been swapped out for a plate of densely packed, light sensitive, on/off switches. Another bundle of on/off switches then surveys the group huddling behind the lens, asking each one, “has a photon knocked you upside the head and turned you on? Or are you still alone in the dark? These questionnaires would be filled out, perhaps sixty times a second, or however often the second group of switches was instructed to do. Then they are all reset to off after each sampling.
For us, it’s complicated. The on/off switches huddling behind the cornea seem much like a digital camera, but actually, these light sensitive neurons do an awful lot of deciphering of what meaning the information contained in the beam of light streaming in might be important to the whole organism, before sending it down the pipe. Our brains never get to see the actual video. Instead, it gets handed the quickly scribbled notes from the group on the front line, who have already turned the picture into lines that define the edges of whatever shapes are in the beam of light. And how do they do this? I’m sure your curious mind is asking. Well, the technical term would be ‘center surround receptive field’, but basically, they talk to each other. “Hey, what do see over there?” It’s bright,” might be the answer, while the one asking might say, “I’m dark, hmm… There must be something going on between us, let’s ask the others.” And then some clever neuron, probably the teacher’s pet, chimes in with, “I’ll bet… That if we follow the trail of disagreements between one neuron and his/or her, buddies around them, we can draw lines and make out shapes that would be useful.” Teacher’s pet then continues with, “then we only have to report those kinds of things back to the main office.”
Cone Cell: (Teacher’s Pet, in this case) “With our ability to see in finer detail, and in color, the main office should be able to tell if that shape we just sent is a bear. Good thing we’re here.”
Rod Cell: “Oh give it rest for crying out loud! ‘We’re better this, we’re better that’, you say. We’re the ones who sound the alarm of possible danger. Then you swoop in and take all the credit as if we were never here.”
Cone Cell: “Well I don’t see anyone dragging your sorry asses all the way to Vermont in the Fall to see the beautiful… Grey!” (bunch of cone cells giggling)
Rod Cell: “Always so high and mighty you are fancy pants. But you can’t see diddly squat in the dark. What, do you think bears don’t exist in the dark!? At night, you’re about as useless as a freakin’ Lamborghini in a snow drift! We’re the work truck that keeps us alive!” (‘yah, what he said’, other rods chime in)
Optic Nerve: “Stop it! All of you! Didn’t I say this kind of bickering can lead to macular degeneration?!”
Rod Cell: (mumbling) “m- might of mentioned it.”
Cone Cell: “he started it!”
Optic Nerve: “Shush!”
Rod Cell: (still mumbling) “Macular degeneration isn’t our problem anyw…”
Optic Nerve: “Zzzt!”
Well, I started writing a story of an annual pilgrimage made by six families to a tiny farm in central Missouri’s grape growing country… And this fell out of my head with a giggle, instead. A second attempt at the intended story will be made sometime in the future.