This is from a paper on Synesthesia by Richard E. Cytowic, M.D., author of
"The Man Who Tasted Shapes", a good laymans introduction to the primacy of
the paleo-mammalian brain (limbic system) over the cortex.
(Sorry, in advance, about the length. I clipped as much as I could
without losing context.)
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Synesthesia: Phenomenology And Neuropsychology
A review of current knowledge
Richard E. Cytowic 1995
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4.15 "Noetic" is a rarely used word that comes from the Greek nous,
meaning intellect or understanding. It gives us our world "knowledge,"
and means knowledge that is experienced directly, an illumination that
is accompanied by a feeling of certitude. James spoke of a "noetic
sense of truth" and the sense of authority that these states impart.
Although so similar to states of feeling, mystical states seem to
those who experience them to be also states of knowledge. They are
states of insight into depths of truth unplumbed by the discursive
intellect. They are illuminations, revelations, full of
significance and importance, all inarticulate though they remain;
and as a rule they carry with them a curious sense of authority for
after-time <3>.
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8. The Implications Of Synesthesia Regarding The Primacy Of Emotion
8.1 Possibly because we have historically held a dichotomy between
reason and emotion, we have misunderstood and even minimized the role
that emotion plays in our thinking and actions. I want to make clear
that the following comments are not a direct cause-and-effect of
synesthesia, but an implication resulting from its physiologic basis.
The two-fold key to this implication is: (1) appreciating the major
role that the limbic brain plays in synesthesia; and (2) considering
newer non-hierarchical models of brain organization.
8.2 The word "multiplex" is usually applied to contemporary concepts
of brain organization that take into account volume transmission,
distributed systems, non-linear dynamics, and the thermodynamic energy
costs of any given biologic neural process. Such newer models remain
largely unknown, a surprising unfamiliarity given their implications -
for example, that we are irrational creatures by design and that
emotion, not reason, may play the decisive role both in how we think
and act. Additionally, our brains are not passive receivers of energy
flux, but dynamic explorers that actively seek out the stimuli that
interest them and determine their own contexts for perception. Ommaya
(in press) has elegantly articulated a number of powerful
contradictions in conventional models of brain organization that led
to his reevaluation of the role of emotion in cognition and behavior.
Indeed, he describes consciousness as "a type of emotion," and one of
emotion's roles as a "cognitive homeostat".
8.3 The conventional hierarchical model implied that the limbic system
was left behind as the neocortex burgeoned during evolution. If so,
then human emotions are comparatively primitive, no more sophisticated
than those of other mammals. Below the level of mammals, the limbic
system is not seen in its developed form, but once we reach the
mammalian line it undergoes robust elaboration. This development,
however, occurs in tandem with that of the neocortex. Some mammals
emerge higher in one dimension than another: rabbits, for example have
well-develop limbic brains compared to their neocortical development,
whereas monkeys show the opposite trend. Humans are unique among
mammals in being well-developed in both limbic and neocortical
dimensions. In humans, the relationship between cortex and subcortical
brain is not one of dominance and hierarchy, therefore, but of
multiplex reciprocity and interdependence.
8.4 Anatomically, the number of human limbic fibre tracts is greater
both in relative size and absolute number compared to all other fibre
systems. Thanks to new techniques, we have only recently realized that
there are more projections from the limbic system to the neocortex
than the other way around. In other words, we had the primary
direction of flow backwards all these years. While we think that the
cortex contains our representations (or models) of reality - what
exists outside ourselves - it is the limbic brain that determines the
salience of that information. Therefore, I join Ommaya in arguing that
it is an emotional evaluation, not a reasoned one, that ultimately
informs our behavior.
8.5 I am hardly rejecting either reason or the role of the neocortex
in objective assessment or assigning meaning. Though we quickly speak
of reason dominating emotion, the reverse is actually true: the limbic
brain easily overwhelms thinking.
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8.8 Emotion did not get left behind in evolution. Reason and emotion
evolved together and their neural substrates are densely
interconnected. Yet each concerns itself with a different task. The
word "salience", which means to "leap up" or "stick out", describes
how the limbic brain alerts us to what is meaningful. We might say
that the emotional brain deals with qualitatively significant
information.
8.9 The limbic brain's use of common structures for different
functions such as memory, emotion, and attention may partly explain
why humans excel at making decisions based on incomplete information,
"acting on our hunches." We know more than we think we know. And yet
are we not always surprised at our insights, inspirations, and
creativity? And do we not just as often reject our direct experience
in favor of "objective facts" instead?
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9.4 Reason is just the endless paperwork of the mind. The heart of our
creativity is our direct experience and the salience that our limbic
brain gives it. Allowing it to be that does not stop us from
overlaying rational considerations on it - after which we can talk,
recount, explain, interpret, and analyze to our heart's content.
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10.18 Just as I argued that our passion for a detached and "objective"
point of view has diminished other kinds of knowing, so too I see that
the experimental emphasis on deficits is gradually smothering the
clinical method of symptom analysis. And herein lies the friction
between cognitive scientists, who think abstractly and in terms of
computation, and those scientists who think clinically and in terms of
biology.
Comments anyone? (sorry, again about the length of this post)
Prof. Tim
"Thinkin' wid dat old brain again"