The Asymmetrical
Brain is a collection of essays in the field of
cognitive neuroscience purporting to report on progress on research on brain
functional asymmetries. The study of brain asymmetry  began in the nineteenth century when researchers found anatomical
differences between the two cerebral hemispheres of humans stating the
right-left asymmetry of the sylvian fissure (1884), the left resulting longer
and running less steeply than the right. Besides anatomical asymmetries,
behavioral asymmetries, such as the right-hand preference, were already known
but it was with the discovery (Dax, Broca) of the phenomenon of lateralization
of language that the general concept of brain asymmetry emerged. Brain
asymmetry, handedness and language laterality are closely connected in a
complex way and are affected by many factors such as genetics, developmental
events, experience and disease, neurochemical asymmetries. Moreover, brain
asymmetry has been observed in most biological systems anatomically,
functionally, and behaviorally.

The study of brain
asymmetry and lateralization phenomena provide thus a keynote for different
disciplines  such as psychology,
psychiatry, neurophysiology, neurology, neurosurgery. The Asymmetrical Brain,
is an updated revision of Brain Asymmetry (MIT Press 1995, by the same
authors) and presents the most recent thinking in the field of functional brain
asymmetries as related to structural asymmetries. The main these of the book is
that "the folk belief that the left brain hemisphere is dominant for
language and the right for visuospatial functions is incomplete and even
misleading". Asymmetries are shown at all levels of the nervous system and
apply not only to higher cognitive processes such as language but also to
emotional processes.

The book is
organized in seven sections each focusing on a specific aspect or technique:
animal models and basic functions, neuroimaging and brain stimulation studies,
visual laterality, auditory laterality, emotional laterality, neurological
disorders, and psychiatric disorders. Most articles addresses the professional
audience of neuroscientists, some of them reporting experimental results on new
neuroimaging and neurostimualation techniques such as magnetic resonance
imaging (MRI and fMRI), positron emission tomography (PET),
magnetoencephalography (MEG) and transcranial magnetic stimulation (TMS). This
is new technical material not contained in the previous publication purporting
to provide evidence for a more detailed refinement of asymmetry. Even so, the
whole book is a useful and very enjoyable reading also for philosophers of
science concerned with cognitive science as well as for the educated reader
interested in or just curious about the fascinating study of how the brain
works. 

© 2003 Giuseppina Ronzitti

Giuseppina Ronzitti holds a
Ph.D in Philosophy of Science (2002). Her research interests inlcude Logic and
Philosophy of Mathematics.

Categories: Philosophical, Psychology