The Tantalizing Biology of Art- Ⅰ

Abstract

The relationship between art and science dates back to the Italian Renaissance, where science often informed the way people painted. Leonardo da Vinci’s concept of the ten functions of the eye was later confirmed by neurophysiologists. In recent years, they have discovered ways in which artists exploit the way vision works to create illusions of reality. Evolutionary biologists are also asking what art is for, and some believe it’s a specific, evolved capacity with a purpose. The visual cortex of the brain is divided into several areas and is where artists play their games. Research has shown that certain areas of the visual cortex are particularly sensitive to certain stimuli, such as color or movement. These findings have been used to better understand artistic technique. 

“All religions, arts and sciences are branches of the same tree. All these aspirations are directed towards ennobling man’s life, lifting it from the sphere of mere physical existence and leading the individual towards freedom.”

-Albert Einstein

Admiring a Van Gogh or Moner painting, people often forget the role of science in art. However, during the Italian Renaissance, science and art were closely intertwined. Artists used their knowledge of geometry and anatomy to create more accurate works, and they also speculated about the perception of art. Today, artists rarely seek scientific advice, but the legacy of this interconnection can still be seen in the conventions of Western art established during the Renaissance.

Leonardo da Vinci, that archetypal Renaissance man. conceived of what he called the ten functions of the eye. These were darkness, light, body, colour, shape, location, distance, closeness, motion and rest. He also came up with the idea that although the images of objects travel physically from the front of the eye to the imprensiva (now called the retina), they are actually formed in the sensus communis (the imagination or the brain).

Those were bold guesses. But as neurophysiologists have investigated the way in which vision works, they have found that Leonardo was right on both counts.

On top of that, over the past few years, they have discovered ways in which the tricks employed by artists exploit these divisions of labour to create illusions of reality. That provides some answers to the question “how?”. Neither is the question “why?” being ignored. Evolutionary biologists are now asking themselves just what art is for. And some are concluding that it is not merely an accidental manifestation of human intelligence, but a specific, evolved capacity with a clearly defined purpose.

Art for Science’s sake

When a beam of light is focused by the cornea and the lens, at the front of the eye, on to the retina, at the back, it stimulates photosensitive cells known as rods and cones. Rods are sensitive to all wavelengths. Cones, which are responsible for colour vision, come in three varieties, each tuned to particular wavelength.

A stimulated rod or cone emits an electrical impulse, which in turn stimulates an impulse in a nerve cell. This travels into the brain along an optic nerve (there is one for each eye) to arrive at one of two small clusters of nerve cells called the lateral geniculate bodies. These are split into two layers, the magnocellular and parvocellular systems. The role of the magno cells is to signal contrasts in brightness, while the parvo cells react to both brightness and colour. After that, the divided signal is channelled for analysis to the visual cortex, a large, convoluted region at the very back of the brain.

It is here, in the visual cortex. that artists play their games. For it is here that the signal is really chopped into Leonardo-like categories before it finally emerges, by processes as yet poorly understood, as what the possessor of the brain in question perceives as visual reality.

 

The visual cortex is divided into some two dozen areas, but the most thoroughly investigated are those that handle the incoming signal first. These are named, rather prosaically, Vi. V2, V3. V4 and V5. Each has a specific function or functions. The first. Vi, has three subdivisions of cells, each of which processes a particular part of the signal from the magno or parvo cells, and then sends the result to the second area, V2.

One of the leading exponents of research on these areas is David Hubel, of Harvard University. A few years ago his colleague Margaret Livingstone realised that the results might be brought to bear on the question of artistic technique. To determine which visual signals are the most important to each subdivision of Vr, Dr Hubel’s group (among others) has measured the electrical responses of its nerve cells to a range of stimuli. The differences between individual cells are striking. Some are activated by colour or brightness but not at all by shape or movement. Others are sensitive to orientation but not to colour or movement.

The researchers then turned to V2 (the next region to receive the signal) and exposed it to the same stimuli. By following the path of the signal electrically-and viewing slices of V2 tissue under the microscope-they discovered that Valso has three subdivisions, each of which receives its input from one of Vr’s subdivisions.

“Art does not simply reveal God: it is one of the ways in which God reveals, and thus actualizes, himself.”

-Friedrich Hegel