corticalcolumns July 10

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Cortical Columns

“I swear I put it down right here,” he thought to himself, “right next to this column.”

He looked up; there were many columns. Towering, Ionic pillars draped with sheer golden cloths loomed over him. They were geometrically ordered in rows of hundreds, perhaps thousands.[1]

“Where did – “ he stopped mid-thought to look around. “This is unreal.”

It wasn’t the first time he had left his textbook in the neo-classical library of his proud, not-so-neo-classical university. This was the first time, however, he found himself in this strange, seemingly endless room of repetitive ivory columns. The air was clean, but laced with a subtle musk. Likely the basement, he concluded.

He meandered down an aisle, the dusty, cracked floor slipping beneath his feet. Passing several rows, an inscription on a pillar ahead caught his eye. Scribbled just at eye level he found an engraving that read, “Hubel & Wiesel, 1961.”[2]

“What an unfortunate last name,” he muttered, increasingly confused about where he left that damn textbook.

Pausing to look up, he noticed that each column was clearly delineated into six uneven sections, each with slightly different embellishments. [3]  The pillars seemed even taller than they were several rows back, as if the ceiling was mischievously slanted to produce an unsettling optical illusion. He blinked, shifting his vision to try to get the whole scene in focus.

All of a sudden, the ground began to shake wildly. It came alive with sparks and subsequently lightning shooting up through minuscule cracks in the pavement. The former quiescent and majestic scene became (quite literally) electric, intensifying with every passing bolt.[4]

Quickly – he was always good at pattern recognition – he realized that the lightning was not random, but rather followed a precise sequence in groups of columns. As he scanned the room, subsets of columns appeared to light up together, followed by neighboring subsets. After several iterations, the sequence randomized and reversed, almost as if it was changing with his perspective.[5] The entire room became a dancing, semi-ordered spectacle of pyrotechnics, as if he had inadvertently walked into a Pink Floyd concert.

Straining to look at the bright light, he followed the lightning as it jumped from different sections of each column: beginning with the fourth, up to the top three, and then down to the fifth and sixth and back into the ground. Again and again, he watched: four, two/three, five/six, down and out. The sequence was alarmingly familiar.[6]

A rough wind moved through the columns, and two layers of dark storm clouds collected to form a surreal double-decker hurricane. Lightning frolicked from column to column, isolated in its two separate clouds. It rumbled locally and then diverged to distant rows of (he imagined) similar columns.[7] The scene was terrifying, yet beautiful.

Soon enough, terrifying won out. The winds strengthened and thunder rolled through. “It’s time to get out of here,” he decided, and chose an arbitrary direction to (attempt an) exit. The textbook was clearly doomed. Emboldened rain pushed its way through the clouds and pelted his face; somehow, only his face. He stopped running and realized… he was drooling. A terrible side effect of having allergies and a heavy jaw.

Disoriented but slowly lifting his head, he looked down to see Principles of Neural Science on the desk. The columns were gone, replaced by standard rows of shelving units. The textbook was opened to a diagram of visual cortex within the section titled “The Constructive Nature of Visual Processing.” Constructive indeed, he thought.

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Editor’s Note

This piece is part of a new series of brain-inspired short stories that we’ll be featuring here on NeuWrite. We’d love to hear who you are what you thought about it – tweet us at @NeuWriteSD!

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Footnotes

NrSmtc56[1] The cerebral cortex, the crinkled outer part of our brain, can be organized into what are often called “columns” of neurons. Depending on which part of the cortex you’re in, these columns have different functions. In visual cortex, each column is responsible for a specific region of your visual world and can compute information about the features of that region.

[2] Like our protagonist here, Hubel & Weisel stumbled through visual cortex, but they weren’t quite sure what they were looking for. In a remarkable set of studies, these scientists uncovered the basic organization of our primary visual cortex, and ultimately won the Nobel Prize for their efforts.

[3] Each of the columns in our visual cortex has roughly six layers, each with a unique set of cells and electrical properties. The height (or really, depth) of these columns and their layers depends on which part of the cortex you are in.

[4] Communication between neurons in the brain is partly chemical but also largely electric. When neurons fire action potentials, the scene is so electric that we can measure the activity with fairly simple electrodes.

[5] As you look around a scene in your environment, different parts of your visual cortex become active in a sequential manner. This occurs because it is organized “retinotopically” -  each area of cortex corresponds to a region of visual space; as you move to a neighboring set of columns, you move to a neighboring region of space.

[6] This is what is thought of as the “canonical circuit” of cortex function. Information comes into layer four from the thalamus, goes up to layer 2/3, and then is sent to layer 5/6 which has large neurons with long axons to send this information to deeper parts of the brain below the cortex.

[7] After information is dealt with in the local columns, it is then sent out to other areas of the brain. There are two major highways in the cortex, through layer 2/3 and layer 5/6. In addition to layer 5/6 sending information to far away targets, layer 2/3 communicates with other neurons in its layer.

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Recommended Reading

The Primary Visual Cortex, an informative website from University of Utah.

Mountcastle, V.B. (1997). The columnar organization of the neocortex. Brain 120, 701-722.

Harris, K. D., & Mrsic-Flogel, T. D. (2014). Cortical connectivity and sensory coding. Nature, 503(7474), 51–58. doi:10.1038/nature12654

Hubel, D.H. and Wiesel, T.N. (1962). Receptive fields, binocular interaction and functional architecture in the cat’s visual cortex. J Physiol 60, 106-154.

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  © Ashley Juavinett, 2014