1. In the 17th century Descartes (1596-1650), an eminent mathematician and philosopher, asserted that the mind "can
work independently of the brain". This distinction between mind and
body has continued down to our own day (as the mind-body dualism) and has
strongly influenced Western thinking. One consequence has been that until
quite recently questions about the nature of 'mind' have been regarded
as not within the province of science at all.
2. The prevailing view of most contemporary (reductionist) biologists
is that all properties of the mind are implicit in the properties of neurons,
and their interactions. The mind is viewed as a process, not as a thing.
Even if the reductionist view ultimately proves to be useful, this would
neither preclude nor undermine the study of high-level functional properties
of the nervous system (NS), such as those in psychology (e.g., studies
of short-term memory).
3. We are not born with a knowledge of our world. Possibly the
world is a "blooming confusion" for an infant. As we mature we
gradually build up a world view. That world view can vary remarkably among
different cultures and even from one individual to another within a given
culture. We are born with (i.e., genetically endowed with) structures which,
over time, enable us to create working mental "models" of the
world (i.e., our physical and social environments) and of ourselves. Each
individual model provides a representation of some aspect of the world.
In some sense our world-view must be a composite of these different models.
Building such models presupposes complex abilities on the part of the machinery
of the NS. A curious feature of our world-view is that we have very little
conscious awareness of the underlying model-building process itself.
4. A remarkable feature of our world-view is its seeming coherence.
Contrast our "Visual World" (our mental model based on visual
input) with the Visual Field ("out there") at any given time.
A trivial example is provided by the blind spots in our retinal field due
to the absence of receptors in the retina where the optic nerve exits.
The CNS "papers" over this defect in the visual field. Note that
our Visual World seems to have no boundaries, whereas our Visual Field
has definite boundaries. Our Visual World is stable, whereas our Visual
Field is constantly changing, due to eye movements. In our world-model,
"time" (whatever that may be) seemingly flows continuously and
irreversibly, although our neurons only fire discretely. Thus our world-model
appears "seamless" in both space and time. (However, the concept
of an absolute linear time is of very recent vintage, having been essentially
invented by Newton). It is important to recognize that our mental model
of the world need not (and does not) correspond to a Western concept of
:reality" in any simple way. (We gloss over the fact that the very
notion of objective reality - as something independent of ourselves - is
fraught with difficulties). Our mental models are built from high level
abstractions of the actual universe. But we know from innumerable experiments
in physics that the universe "out there" is very different from
our mental model of it.
For example, the chair you sit on is mostly a vacuum. A neutron particle
can easily pass eight thousand miles through the earth without hitting
anything. Grass is not really 'green', and must look different to organisms
with visual systems different from ours. Thus our various working mental
models of the universe sift out certain of its abstract relationships and
build representations from them.
5. Another remarkable feature of the CNS is the speed with which
some tasks, such as the recognition of faces, or speech interpretation,
are carried out. We know that the synaptic delay time is of the order of
a few milliseconds. Since recognition or interpretation can take place
on the order of a second or less; this means that the recognition process
could only involve at most a 100 -1000 serially-connected neurons. Most
of the "computation" must be going on in parallel.
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