The Binding Problem
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in the recognition of shape: In severe cases they can see a displayed drawing, but
are unable to tell whether it’s a square or a circle, or are unable to discriminate
between an X and an O. In other cases, the patient sees objects clearly but they
are stripped of meaning. Some brain lesions are so specific that the patient
is impaired in the recognition of just one category, for example fruit and
vegetables.
The most dramatic reported cases of visual agnosia are of patients whose
lesion is in the motion-detecting area of the cortex. In one well-documented
case, the patient was unable to see objects in motion: Her disability was
described as follows: “She had difficulty, for example, in pouring tea or coffee
into a cup because the fluid appeared to be frozen, like a glacier. In addition,
she could not stop pouring at the right time since she was unable to perceive
the movement in the cup when the fluid rose.”
As visual information travels through the brain, it passes through separate
regions for the analysis of color, depth, movement and shape. These regions
are different from one another in their anatomy, their physiology and their
chemistry. Each process operates on its own timescale and in its own fashion.
One expects, then, that there is a terminal end of this progression, where all the
streams come together and their contents are integrated to yield a composite
image. The most surprising fact of all is that there is no apparent terminus in
the physical brain. Quite the opposite: The nerve fibers from these separate
processes diverge further and further, and their signaling is distributed over the
entire cerebral cortex.
Since animals see a coordinated image in which every object has its proper
shape and things move coherently in space, the information parsed by the brain
is assembled and comes together somewhere. However, no-one knows where
or how visual information comes together to yield a systematic, unitary image.
In brain research, this is called the binding problem, and it is not likely to be
solved anytime soon. It is plausible that before it is solved there will have to be
a paradigm change in brain biology and fundamental physics.
There are several speculative theories to account for binding. According to
one, there are zones of convergence in the brain where a great many nerve fibers of
the visual system converge to a single “Grandmother cell” which combines the
information they contain. However, as the British neurobiologist Semir Zeki
affirms, this actually explains nothing. Information “coming together” is much
more than the confluence of physical streams, or wires, which conduct the
coded signals: What must be synthesized and come together is the information
content of the signals, not the bare physical signals. The signals merely code the
content: There is no inherent relationship between the coded signals and the
21
in the recognition of shape: In severe cases they can see a displayed drawing, but
are unable to tell whether it’s a square or a circle, or are unable to discriminate
between an X and an O. In other cases, the patient sees objects clearly but they
are stripped of meaning. Some brain lesions are so specific that the patient
is impaired in the recognition of just one category, for example fruit and
vegetables.
The most dramatic reported cases of visual agnosia are of patients whose
lesion is in the motion-detecting area of the cortex. In one well-documented
case, the patient was unable to see objects in motion: Her disability was
described as follows: “She had difficulty, for example, in pouring tea or coffee
into a cup because the fluid appeared to be frozen, like a glacier. In addition,
she could not stop pouring at the right time since she was unable to perceive
the movement in the cup when the fluid rose.”
As visual information travels through the brain, it passes through separate
regions for the analysis of color, depth, movement and shape. These regions
are different from one another in their anatomy, their physiology and their
chemistry. Each process operates on its own timescale and in its own fashion.
One expects, then, that there is a terminal end of this progression, where all the
streams come together and their contents are integrated to yield a composite
image. The most surprising fact of all is that there is no apparent terminus in
the physical brain. Quite the opposite: The nerve fibers from these separate
processes diverge further and further, and their signaling is distributed over the
entire cerebral cortex.
Since animals see a coordinated image in which every object has its proper
shape and things move coherently in space, the information parsed by the brain
is assembled and comes together somewhere. However, no-one knows where
or how visual information comes together to yield a systematic, unitary image.
In brain research, this is called the binding problem, and it is not likely to be
solved anytime soon. It is plausible that before it is solved there will have to be
a paradigm change in brain biology and fundamental physics.
There are several speculative theories to account for binding. According to
one, there are zones of convergence in the brain where a great many nerve fibers of
the visual system converge to a single “Grandmother cell” which combines the
information they contain. However, as the British neurobiologist Semir Zeki
affirms, this actually explains nothing. Information “coming together” is much
more than the confluence of physical streams, or wires, which conduct the
coded signals: What must be synthesized and come together is the information
content of the signals, not the bare physical signals. The signals merely code the
content: There is no inherent relationship between the coded signals and the