Battro’s book recounts the case of Nico, a student
and subject at his research laboratory. 
The author, a cognitive psychologist interested in educational and
developmental issues associated with brain trauma, meditates upon what that
case may mean for various theories of human mental life and development. Nico, born with a congenital defect of the
right half of his brain , suffered from partial motor paralysis to his left
side and debilitating epilepsy before, at age 4 years, undergoing a functional
hemispherectomy. In this procedure,
doctors removed areas of his cortex and all of the temporal lobe on the right
side. The remaining portions of the
right hemisphere were left intact but completely disconnected from the brain
stem and left brain, effectively reducing his brain matter by one half. Obviously, this is an extreme intervention,
and a rare one; Battro estimates that there are perhaps 100 persons worldwide
who have undergone such an operation.

From a medical point of view, the
operation was a success, producing a complete cessation of seizures. More importantly yet, and as the title of
the book suggests, Nico appears to have lost very little, if anything, in the
process. Indeed, he retained his
ability to speak throughout the recovery period, and was up and walking again
within days of the surgery. Although
some difficulties persist in terms of left-sided vision and motor control, Nico
shows no further evidence of disability, despite what initially seems a
profound neurological loss. Indeed,
Battro recounts that he was deeply surprised to learn of Nico’s exact condition
after the boy was brought to him for therapy. 
Nico, he reports, is an eminently likable boy, and furthermore an
intelligent one, attending the usual classes for a child his age, and placing
at the top among his peers in terms of both spoken and written language.

These observations lead Battro to
his central question: "How can
half a brain sustain a full mind?" (5). 
As he points out, the half-brained person who retains nearly full
capacity raises a number of hard questions for theories relating
"sidedness" to specific brain functions, and connecting brain size
directly to capacity. His point is made
quite strongly when he reminds us that a half-brained person like Nico actually
has less functioning brain matter than does the average microcephalic, but
without any of the attendant serious deficits. 
Since Nico, age 9 at the time of writing, has shown normal acquisition
of mental skills, his case poses a serious challenge to any theory that would
too simplistically link usual brain-structure development to this acquisition
process. Battro argues,

that hemispherectomy is more than a
neurological lesion… [but] amounts to
rebuilding a new brain [as the] half hemisphere is functionally transformed
into a whole brain again (25).

Indeed, the case study here is an
interesting puzzle that deserves to be considered by anyone interested in
relations between learning and mental capacity. That a half-brained child can develop more or less normally
suggests a number of lines of thought. 
It might be argued, for instance, that the right half of the brain,
which Nico lost, is pretty much unnecessary, and that the advanced "mental
organs" are all in the left half, or that the brain contains massive
redundancy, with functional areas duplicated in each half. In either case, such a claim raises many
puzzles about the brain’s efficiency and design. Another issue concerns the mechanism that forces (or even allows)
the compensatory development seen in Nico’s case. At present, such a mechanism is not clearly understood; one
particular question about it would be why some patients, with seemingly far
less serious local brain lesions, never recover their individual capacities,
whereas Nico was able to recover nearly everything even after his drastic
cortical sacrifice.

One of the virtues of Battro’s book
is that he never suggests that he has answers to these questions where he does
not. Instead, he wants simply to point
out where these puzzles arise, and to suggest the great and fundamental
mysteries that persist when it comes to our understanding of the brain.

The book is not highly technical,
and is suited to the general reader, and at the same time contains detailed
notes, with pointers to relevant literature, for those interested in following
up on the scientific and medical issues raised in greater depth.

At the same time, the book is not
without its positive platform. Battro
is particularly interested in the use of computers as educational aids for
children facing developmental challenges; however, those parts of the book that
recount some of his ideas and experiences in this area are suggestive, but
ultimately less satisfying. On the one
hand, he writes convincingly about the benefits of computers for someone like
Nico—for instance, while his motor skills make handwriting difficult, the use
of a computer keyboard allows him to demonstrate his real capacity for written
language. On the other hand, his
enthusiasm for computers and other "neural prostheses" leads him to
some more debatable suggestions, and to some leaps in argumentation. For Battro, the fact that "the human
cortex is so well-endowed as to be able to accomplish the same cognitive feats
with only half of its neurons," implies that it might then be possible,
"with the help of some external computational aids, for the brain to
attain incredible levels of competence" (12). This is interesting, but puzzling. Battro never commits himself to any particular understanding of what
is meant by an "incredible" level of human cognitive ability, nor
does he claim that such ability would necessarily follow from the use of
computers. Still, the contained
implication that technological advances can lead to expanded human mental ability
goes beyond the little evidence he provides, and does not obviously follow from
the natural healing processes evidenced in Nico. Furthermore, the idea of "untapped abilities" in the
brain reminds this reader of the sorts of naive theories of human mental
ability—the mythical belief, for instance, that human brains use only some
small percentage of their real capacity—that Battro himself calls into
question.

Furthermore, Battro’s arguments
about the use of computers rely on a somewhat dubious distinction. In his later chapters, he describes the sort
of "cortical shift" apparently induced by technologically-mediated
interactions with the world, making much of what he calls the "different
cognitive strategies" involved in the use, for instance, of word processing
programs rather than other means of producing written language. But the distinction, drawn on page 59,
between Nico’s use of a "machine" in his connection to the
environment, rather than what Battro calls "the handwriting
shortcut," seems to overstate the advance represented by the switch to
computer composition. Battro does not
make clear why use of a computer is not simply the use of a different
machine than employed when one uses pen and ink, or indeed any writing
tool. While computers are clearly
different than other mechanical aids in their particulars, it is not clear that
this difference is one that makes a difference. While Battro raises some interesting possibilities when he
considers the use of computers to allow persons to perform tasks they otherwise
could not, or using different modalities than usual—programs that allow persons
to draw pictures using written commands, for instance—the claim that this
points to a fundamental alteration in human cognitive abilities is neither
convincing, nor completely clear, and occasionally slips into metaphors, like
the "brain wide web," which obscure more than they reveal. All in all, the book’s positive proposals
are less interesting than the many questions it raises.

Finally, it should be noted that Half
a Brain Is Enough can be somewhat unsatisfying. A slim volume at only 90 pages of text, it contains far more
recapitulation than is necessary or desirable in such a short work. Each chapter reads as if it may have once
been a stand-alone piece, and this induces an experience of
repetitiveness. As indicated, it does
raise a number of interesting questions, and so can provide a fine starting
place for someone interested in cognitive and developmental psychology. At the same time, however, more facts
concerning the case—particularly about Nico’s process of cognitive
development—could easily have been included, even in this short space, by
excluding some of the repeated materials, and probably ought to have been. Battro’s style, too, will not be to all
reader’s tastes. He speaks in the
personal and narrative manner that has become popular after the success of the
case-study style popularized most notably by Oliver Sacks; unfortunately,
Nico’s personality is not rendered with the literary eye to detail of that
authour, and so the boy remains something of an abstraction. As a result, while those looking for a
purely scientific recounting of a medical case may be put off by the personal
tone, those looking for an engaging presentation of the human character of the
half-brained condition are also likely to find themselves wanting more than
they are given.

©
2002 M. Allen

M. Allen is an ABD student in philosophy
at the University of Pittsburgh, currently working on the subject of formal
similarities between various apparently distinct logical systems. In addition, he is pursuing a second
graduate degree in computer science at the University of Massachusetts,
Amherst. His interests include
theoretical computer science and artificial intelligence, particularly
resource-bounded reasoning.

Categories: Memoirs, General