final blog entry

"Is this a shortcut?" he asked, leaning from the back-seat over the car's center console.

I couldn't tell. In ten minutes of driving - complex motor control, visio-spatial maneuvers, object recognition tasks and optic flow calculations, my mind had managed to concern itself solely with a maths problem. Nothing trivial, either; it had my complete attention. Had I been driving impaired?

I had certainly not been phenomenally conscious, but this hadn't involved concomitant loss of perception, reasoning, or motor control. This started me thinking - I know from research into attention that the brain receives much more sensory input than can be actively, or consciously addressed. Much of this information, however, is access-conscious. That is, "actively poised for direct control of reasoning, reporting, and action" (Block 1). Loss of phenomenal consciousness has been observed in patients exhibiting "Reverse Anton's Syndrome", in which patients do not realize that they aren't really blind (Hartmann et al.). These patients are at chance level when asked whether a room is dark or illuminated, but when stimuli are presented to a specific part of their visual field, they are able to report that a recognizable word or face "clicks". Block suggests that this is a kind of visual access without visual phenomenal consciousness. These affected patients generally have damage to V1 with bilateral parietal lesions, leading Milner and Goodale to suggest that phenomenal consciousness requires ventral stream activity plus attention. Subliminal studies have shown that adverse stimuli below the limen can trigger changes in galvanic skin response, indicating that the preconscious mind is able to process these and trigger sympathetic action. What, then, necessitates action by the system of attention?

A theorized cognitive construct, the executive system, is thought to be required in the control and management of other cognitive processes. Norman and Shallice have outlined several tasks which require the action of the executive system for proper function:

1. Planning and decision making.
2. Error correction and troubleshooting.
3. Situations involving novel responses.
4. Dangerous or technically difficult situations.
5. Situations involving the suppression of strong habitual response or temptation.

Since the task of driving in Nashville is so ingrained in my psyche, it seems only that a deviation from the norm would necessitate my explicit attention. If, for example, another driver were to veer into my lane, my attention would be necessary to orchestrate avoidance of the oncoming vehicle. The lag time in diverting my attention from abstract thinking to a spatial task could be injurious, in such a circumstance. But what is this attention, and even more interestingly, its conscious underpinning?

In humans, the cortex has long been thought to be a site for higher-order cognitive processes such as decision making. Crick and Koch assume that the function of the neural correlate of consciousness (NCC) is "to provide the best current interpretation of the environment---in the light of past experiences---and to make it available, for a sufficient time, to the parts of the brain which contemplate, plan, and execute voluntary motor outputs, including language" (Crick and Koch 1). They appropriate the term qualia, the subjective content associated with a conscious sensation, from philosophy, and assume its existence and physical basis in the brain. With these basic neurobiological assumptions, Crick and Koch break the problem of consciousness down into several questions:

What is the difference between neuronal activations that correlate with consciousness and those that do not? What is the character of the NCC? What can we infer about the location of neurons whose activations correlate with consciousness?

From these guiding questions, they outline several promising experimental approaches towards locating the NCC. Bi-stable percepts, such as the Necker cube, may prove useful in examining the conscious mind's alternating wield of perception. They also address binocular rivalry as an example of this alternation. In addition, through neuroanatomical studies, Crick and Koch have claimed that areas such as V1 are not a part of the NCC. This claim was made based upon the fact that V1, in macaque monkeys, does not make any direct projections to the frontal cortex. Ned Block argues that, to make this argument, Crick and Koch have necessarily conflated two separate modes of consciousness. He makes the distinction between phenomenal and access consciousness, and calls their argument regarding the former unjustified, and that regarding the latter trivial. Just like the concept of memory, it is expected that consciousness will be elucidated with its own more complex vocabulary as research progresses.

It has been most interesting to me this semester to consider these questions in the light of perception. How exactly can a physical system with a particutular architecture give rise to feelings and qualia? This will surely be concertedly explored as new imaging and experimental paradigms are developed. It will continue to be a profound interest of mine.

Neural Basis of Consciousness
How Not to Find the Neural Correlate of Consciousness
Crick, F. and Koch, C. (1995),“Are we aware of neural activity in primary visual cortex?” Nature 375, 121-123, May 11
Hartmann, J.A. et.al. (1991), “Denial of visual perception,” Brain and Cognition 16, 29-40
Milner, A. D. & Goodale, M. A. (1995) The Visual Brain in Action. Oxford University Press: Oxford
Velmans M 1991 Is human information processing conscious? Behavioral Brain Science 14: 651-726

a deep tradition

Pre-renaissance art's perspective treatment largely matured in Europe between the 13th and the 15th centuries. Cimabue, an artist of the Byzantine style, attempted to reconcile the limitations of two-dimensional media with his own burgeoning naturalism. Although the Byzantine typically appeared flat and highly stylized, Cimabue's figures took on an organic appearance. In his paintings, proportions were more accurately depicted, and shading was used to lend the works a life-like quality. Though he began a naturalistic movement that would be epitomized in his student, Giotto di Bondone, his own grasp of natural perspective was rather limited. Cimabue's frescoes and altarpieces use occlusion of figures and basic lines of architectural perspective to indicate the third dimension, but rarely contain subjects interacting in more than one depth plane. The apparent size of the figures, as these were primarily sacred works, is often not intended as an indication of distance but of the figure's import to the composition.

Giotto's figures were stolidly three-dimensional, depicted with natural anatomy, and positioned accurately within stylized natural scenes, which often resembled theatrical sets. Although the characters within his work, most notably the interior of the Scrovegni Chapel, were quite lifelike, Giotto's backgrounds often consisted of simple elements. He used these primarily as repoussoir devices to direct the viewer's eye, and not to depict a three-dimensional scene. Despite this, the architectural elements in his work are themselves portrayed accurately, although they are often positioned like set-pieces among disproportionate figures.

The pre-renaissance art of the Florentine and Sienese schools relied on perspective styles that were relatively innovative in context, but that still failed to accurately depict the three-dimensional aspects of space. This would continue to be the case until Filippo Brunelleschi, an architect, invented the theory of linear perspective with his artistic experiments. The use of a single vanishing point and linear perspective allowed Brunelleschi to accurately depict the buildings he built, surveyed, and examined. Hyper-realism reigned, as well, in the work of the Flemish painter Jan van Eyck. Although he was active in the early 15th century, van Eyck's work displays a mastery of perspective rarely seen in his day. Though not strictly faithful to Brunelleschi's linear perspective, his work delighted in the detailed depiction of reality. In his Arnolfini Wedding, van Eyck portrays a simple indoor scene with a mastery of proportions. The crystal chandelier is of such perfect perspective that debate still rages over whether it was possible to paint without an optical aid. Jan includes a mirror, in which the scene is reflected and distorted, signing the frame "Johannes van Eyck hic fuit 1434", or 'Jan van Eyck was here 1434'. His mastery seems almost brash.

Though it was a long evolution to the 3-dimensionality of van Eyck, artists came to understand that linear perspective plays a major role in the perception of depth. As art's focus moved from its stylistic and hieratic aims to realism/naturalism, and eventually back to the abstract, the gains made in the portrayal of perspective continued to appear. Even in the face of the photograph, art has remained largely constant in its fidelity to our perception of depth.

Jan van Eyck
Filippo Brunelleschi

les fauves

How do you see these trees? They are yellow. So, put in yellow; this shadow, rather blue, paint it with pure ultramarine; these red leaves? Put in vermilion.

In 1896, Henri Matisse visited the artist John Peter Russel on the island of Belle-Île-en-Mer, having never seen an Impressionist work previously. He left after only ten days, remarking "I could not stand it anymore."

Of course, strong color would become an emphasis of Matisse and the Fauves. Given the connotation that color can carry, especially when viewed within its cultural context, Expressionist art can be remarkably effective at evincing a wide range of emotions. Artists such as Matisse used formal techniques such as framing and juxtaposition to set apart these colors, to better achieve a simplified and abstracted feel for their paintings. These flat colors were often composed within a painterly style, using broad, harried brushstrokes and impasto. The technique appears and is relatively simple, though these artists honed their sense for depiction by studying the theory of color. The Fauvists chose color as their chief tool of expression, but many other artistic techniques play upon our perceptive tendencies.

Benday dots were widely seen in the work of Roy Lichtenstein, but they are inherited from the Pointillist tradition. Distinct points of primary color can suffice to represent a wide selection of secondary and intermediate colors when used deliberately in small scale. This technique requires the mind of the viewer to mix the color spots into a fuller range of tones during the process of perception, and was used to great effect by those such as Seurat.

Schwarz suggests that neuroplasticity plays a role in interpreting a pointillistic image. In his The Mind and the Brain, he suggests that priming with pointillistic theory can alter the image perceived by a subject. It is remarkable that the brain can construct a contiguous image from many disparately colored dots. Even when these dots are enlarged, the image can be resolved from quite a low spatial resolution. Our ability at this might not rival that of other species, but it is a testament to the unrivaled interpretive power of the mind.

Pointillism
Fauve
Schwartz, Jeffrey M.; Begley, Sharon (2003). The Mind and the Brain: Neuroplasticity and the Power of Mental Force. Harper Perennial, p 337.

eyes cold

It makes sense that neuronal development would be dually influenced by genetic predispositions and by the actual process of making synaptic connections. The visual system is particularly subject during a baby's early development, as sight gradually comes into focus, and novel visual stimuli seem to figure largely in this process.

According to research, a child's nutrition can also determine the course of brain development, especially when it comes to the visual system. Babies who are breastfed show enhanced stereoscopic vision, and generally have visual systems that are more mature than their formula fed coevals. The scientific establishment to this day has not elucidated the complete chemical composition of breastmilk, but included Omega-3 fatty acids are known factors in visual development. One particularly, docosahexanoic acid (DHA), has been widely implicated for this role, although recent trials have suggested that formula supplemented with DHA and arachidonic acid fails to produce the dramatic developmental benefits of breastfeeding. Other studies have suggested that DHA and other long-chain polyunsaturated fatty acids contribute significantly to the development of visual acuity and the composition of plasma and erythrocyte phospholipids, but many suspect that other factors in human milk play a role in this nutrition.

Animal studies have investigated how the cerebral circuitry is tuned to stimuli in the environment. Each sight, sound or sensation experienced has been shown to refine the nerve-cell connections in a growing brain. However, certain complex organization in the mammalian brain is thought to develop without significant experiential reliance. In a recent study, designed to describe the development of the brain's visual neural network, modular and axial specificity was observed in the brains of very young tree shrews. On the other hand, recent evidence that blockade of cortical but not of retinal activity prevents the development of clustered horizontal connections in ferrets clearly indicates that neuronal activity is required for the development of tangential connections. Similar results have been observed across both systems and species. It seems that the development of the mammalian brain lies somewhere very near the nature-nurture nexus.

a byzantine machine

For most, the calculus of mind has its cold, invariable limits. Attention and repetition allow us the province of only a small set of our experiences, and most of the world's features are simply forgotten. Are these details never present? Are they instead discarded by the subconscious mind?

Some savants have a startling ability to recall experiences and facts, both vital and inane. Often these abilities are associated with a traumatic brain injury or developmental disabilities. In addition to eidetic memories, some individuals also possess prodigious cognitive abilities. Daniel Tammet is one such prodigious savant. Since the age of four, his mind has seen the world as a landscape of numbers. In grade school, Daniel would spend his recess counting the hopscotch scores of the other children. He would gaze endlessly, pondering the patterns in nature and in the lives of his peers. As a synesthesiac, each number looked and felt unique to him. Some were movements, others towering forms, and still others deep and complex feelings.

With each number a separate sensual experience, it's no wonder that Daniel can easily remember them. His recitation of pi to more than 22,000 digits astounded even those familiar with his condition. Even more remarkable are his skills of mental computation. Daniel can operate on numbers to the hundredth digit in his head. He can determine the primality of a number by feeling. He claims that the answers simply appear, without the use of a deliberate algorithm.

Daniel, like some other savants, also has an eidetic memory. In a stunt performed for a British television show, he learned to speak Icelandic, considered to be a difficult and nuanced language, in only a week. To one like Daniel, we must seem blind, deaf, absent-minded.

The present might seem almost intolerable in its richness and sharpness, as Jorge Luis Borges describes it in Funes the Memorious. Like Daniel Tammet, Ireneo Funes is cursed and blessed with supernal memory. His recollections are every bit as sensual as the lives of others, his days vertiginous. Borges writes of Funes: "He could continuously discern the tranquil advance of corruption, of decay, of fatigue ... He was the solitary and lucid spectator of a multi-form, instantaneous and almost intolerably precise world." I cannot imagine the stammering grandeur that reality would hold all at once. We can only marvel at these savants, these insomniacs among us.

sight unseen

It may be essential to our survival that we are hardwired to recognize and respect the human face. Even very soon after birth, a baby's inchoate brain can focus on and seemingly discriminate between faces. Interpersonal relationships, communication and trade, of course, have been indispensable to mankind for eons. It's no surprise, then, that nature would hard-code this instinct into our incipience.

Some more surprising perceptual adaptations occur after birth, and many are largely manifestations of cultural experience. Visual perception, in particular, can be tempered by context and by the perceiver's world-view. Recently, research has been conducted at MIT differentiating between particular perceptive tendencies of Asians versus Americans of European descent. The cultures in question are of course widely different - philosophically and aesthetically, and these differences apparently manifest themselves in subjects' visual perception.

The archetypal Asian world-view revolves around a concept of harmony. Major philosophical movements: Taoism, Buddhism, and Confucianism, all identified with this precept. Asian architecture, largely, is composed horizontally and resonates with the landscape. The ornate roof style of traditional architecture is a gesture to resolve the roof-line of a building in organic forms. This tendency fits into the Asian world-view, in which individual objects are typically seen as parts of larger, organic wholes. When shown a photograph, Asian subjects tended to concentrate disproportionately on the background and larger context of a scene. Americans tended to favor the foreground or most pronounced object.

Western culture and philosophy, too, tend to put more emphasis on the individual. Americans, in this sense, are less aware of context and relativity. This is the American ego - our great, enterprising strength. But it also may have hindered our ability to understand the world around us. Richard Nesbitt, one of the study's investigators, cites the inability of Western scientific minds to quickly grasp the nature of physical forces:

"Aristotle, for example, focused on objects. A rock sank in water because it had the property of gravity, wood floated because it had the property of floating. He would not have mentioned the water. The Chinese, though, considered all actions related to the medium in which they occurred, so they understood tides and magnetism long before the West did."

It may have taken thousands of years for our cultural tendencies to develop, but their effects are ubiquitous. Eye movements and recollections of the participants also tended in the same ways. Kyle Cave of UMass Amherst called this effect "striking", commenting that this kind of effect on low-level perceptual processes suggests another startling, perceptual relation to our cultural origins.

This is doubtless one of many significant effects tempered by culture. Even so, it's implications are astounding.

Visual Perception Tasks
Asian and Western Visual Perception
Eidos
A New Kind of Chop Suey

the eyes have it

One wonders how a structure so complex might have evolved. Vision is an elegant sense, and the human eye has become an extremely specialized organ to its end. One has only to look in the standing water of a pasture to find a possible precursor within the Euglena. These small protists possess an eyespot apparatus; a primitive photo-receptive system which allows the motile Euglena to find a light source strong enough for photosynthesis. The Euglena holds chloroplasts within its transparent body which allow it to undergo this process to manufacture sucrose from water and carbon dioxide. Alga in Euglenaphyceae use a photoreceptor called a paraflagellar swelling near the body's main flagellum. This receptor is interesting in that it is a crystalline structure. The algae uses this dicroic crystalline detector along with a primitive absorbing screen to sense and respond to incident light.

The algal eye of Chlorophyceae contains optics, photo-receptors and elementary components of the signal transduction pathway. Though among the simplest eyes in nature, chlorophycean eyes are capable of detecting light intensity, color, and direction of incidence. Because of their small size, the optical systems on microalgae operate mostly on the basis of reflective surfaces and constructive interference. Although quite disparate macroscopically from the human eye, the chlorophycean eye also uses a rhodopsin chromophore. Retinal is present and used in a slightly different form, but this archaic chromophore is still similar to that used in the human eye. This fundamental system has been nearly conserved from even microalgae.

On early earth-orbital space flights, astronauts were surprised to see this structure staring back at them. It spans nearly thirty miles, and to date no definite scientific explanation has been established for its formation. Because of its scale, the Richat Structure is baffling in its symmetry and basic etiology. It seems that eyes both large and small, given enough time, can pop up in all sorts of places.

Hegemann, Peter. Algal Eyes
Ross, Greg. Futility Closet