It has been a singular challenge to organize a volume on sensory systems that appropriately reflects the
intent of this new edition of the Handbook of Neurochemistry and Molecular Neurobiology. The physiology of
sensory systems relies as much on highly specialized cellular and tissue morphology as it does on unique
neurochemical pathways. Hence, this volume has emerged as a series of discussions that move continually,
seamlessly we hope, between molecular and anatomical views of sensory function. It is by no means
comprehensive, leaving room for additional chapters and updates, as befitting on-line publications such as
this one. Nevertheless, every major sensory system is represented, each with its own blend of molecular,
anatomic, and genetic components. Emphasis has been placed on presenting new discoveries and insights,
rather than providing a textbook review of basic principles. The ‘‘somatosensory system’’ is discussed by
Dr. Roe in a demanding and insightful chapter, which convincingly demonstrates that positional relationships
within the cortex encode for the essential quality of touch, namely the source of the incoming somatosensory
signal with respect to the body plan. The ‘‘visual system’’ is presented by Dr. Sharma and myself from two
perspectives: development and degeneration. Together, these views provide not only an appreciation of
normal retinal function but also highlight the utility of the visual system as a powerful model for uncovering
internal and external clues for development and death of all CNS neurons. Drs. Wu and Zuo in their chapter
on the ‘‘auditory system’’ emphasize exciting new findings from their own work, which explains the important
role of cochlear amplification as a major requirement for auditory processing. Chapters on the chemical
senses, ‘‘gustation’’ (by Drs. Smith and Boughter) and ‘‘olfaction’’ (by Dr. Ennis et al.), focus more on new
concepts of the neurochemistry and molecular biology of transduction events and as such perhaps fit more
neatly in the mold set by other volumes in the handbook. The last two chapters address additional
aspects of the chemical senses, namely ‘‘glucose sensing’’ (by Dr. Roth et al.) and ‘‘CO2/Hþ homeostasis’’
(by Drs. Lahiri et al.). In these cases, the term ‘‘sensory system’’ is used in the broadest sense, and
discussions include a diversity of cell types and tissue locations that function collectively to monitor the
internal milieu.
I offer special thanks to Dr. Abel Lajtha for his heroic feat in bringing to fruition this treatise of amazing
breadth, diversity, and potential importance. Anyone with less than Dr. Lajtha’s world view and historic
grasp of the paradigm shifts resulting from neurochemical research would never have succeeded. What is
more, they could never have even conceived of the plan