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Unifying Brain Thinkers (book review)

Dr. Steve Potter spotter at gg.caltech.edu
Sun Jan 14 19:17:10 EST 1996


Steve Potter, PhD
Caltech Division of Biology
spotter at gg.caltech.edu
http://www.caltech.edu/~pinelab/pinelab.html


³Descartes¹ Error--Emotion, Reason, and the Human Brain²
Antonio R. Damasio, M.D., Ph.D.
1994 Grosset/Putnam, New York ISBN 0-399-13894-3  $24.95 hardcover, 
312 pages.


Cartesian Dualism, the separation of the physical mind (brain) and the
spiritual mind (soul), pervades our thinking about the nature of thought. 
Although Descartes certainly did not originate the idea of some
non-material part of  us that somehow oversees and controls our brains,
this notion he promoted lingers even among many hard-core materialists,
fogging up our view of the way the brain really works.

Antonio Damasio, in his excellent book, Descartes¹ Error, takes out a
giant fan and successfully clears this fog.  The book is entertaining and
not highly technical, however it is a serious, well though-out exposition
on the biology of thought that ought to be read by every neuroscientist,
mind-philosopher, neurologist, psychiatrist, psychologist, cognitive
scientist, and AI researcher.
The divisions between these categories of people interested in brains are,
to a large extent, artifacts of a long history of dualistic thinking that
has separated the thought-stuff (Descartes¹ ³res cogitans²) from the
squishy, wet, tangible body-stuff (³res extensa²).  Damasio tackles this
and a number of other common dualisms, such as reason/emotion,
left-brain/right-brain, analytical/subjective,
brain-controller/body-slave.

Over 100 years ago, the psychologist-philosopher, Williams James realized
the importance of signals from the body in producing emotions: 

   What kind of emotion of fear would be felt if the feeling neither of
   quickened heart-beat nor of shallow breathing...were present, it is
   quite impossible for me to think. (p. 129)

This under-appreciated concept is greatly strengthened by Damasio¹s
Somatic Marker Hypothesis, which asserts the importance of a continuous
dialog between the brain and the body.  Being a true experimentalist,
Damasio describes how people are emotionally impaired when they are
lacking some component of the systems by which somatic markers are created
in the body and read by the brain.  What¹s more interesting, neurological
cases are described in which this emotional impairment results in serious
problems in the domain of reasoning, planning, and decision-making.  Thus,
the emotional, subjective, feeling aspect of our thought processes is
legitimized as having a material substrate, and being a crucial part of
what has traditionally been a separate discipline, that of logic and
rational thought. ³The mind is embodied in the full sense of the term, not
just embrained.² (p. 118)  

Also greatly under-appreciated by neuroscientists and many AI researchers
(but not in this book) is the fact that perception is an active process of
interaction between our brain, our body, and the environment. ³Perceiving
is as much about acting on the environment as it is about receiving
signals from it.² (p. 225)

In a field where everyone is talking about representations in the brain,
as if memories are written down somewhere in our synapses, we need more
theories that emphasize the dynamic, evanescent nature of thought and
recall.  Damasio¹s Œdispositional representations¹ fit the bill:  ³A
dispositional representation is a dormant _firing potentiality_ which
comes to life when neurons fire, with a particular pattern, at certain
rates, for a certain amount of time, and toward a particular target which
happens to be another ensemble of neurons.² (p. 103)  I would add, and
Damasio would probably agree, that the Œtarget¹ keeps moving, e.g., out
into the periphery to the muscles and glands, providing those somatic
markers, and providing a means by which the dispositional representation
can affect the outside world, and thereby have meaning.  When we know a
lot more about how neural activity flows across the synaptic landscape, we
may someday be able to see the Œstatic¹ substrate of these dispositional
representations.  In the mean time, we must be satisfied rolling the ball
down the ever-changing hillside and watching where is goes.

The book covers a monumental range of topics, even including the
biological substrates of the self and of free will.  My only complaint is
a lack of levity.  Although warmly written in the first person, including
personal opinions, feelings, and anecdotes, there is no joking around or
silliness here.  

By clearly describing numerous examples and theories that support
plausible mechanisms by which brain, body, and environment interact to
produce a unified thinking, feeling, reasoning whole, Damasio contributes
something for all of us, and does much to break down the artifactual
barriers between our various brain disciplines.



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