The Parallel Brain

Hemispheric specialization is involved in every aspect of sensory,
cognitive, and motor systems integration. Study of the corpus callosum, the bands of
tissue uniting the brain's two hemispheres, is central to understanding
neuroanatomy, neurophysiology, and behavior. It also brings the tools of hemispheric
specialization to a fundamental problem of cognitive neuroscience: modularity and
intermodular communication.

This book summarizes current research
on the human corpus callosum. It also provides a comprehensive introduction to
cognitive neuroscience. Rather than viewing the field through the various systems of
the mind/brain such as perception, action, emotion, memory, language, and problem
solving, it takes a case studies approach. Focusing on the central problem of simple
reaction time, it examines the most basic possible sequence of
perception-decision-action. The task is to press a button with one hand as soon as a
patch of light is detected in the peripheral visual field. When the patch appears in
the visual field opposite the responding hand, there must be interhemispheric
transfer prior to response. But transfer of what -- a visual input code? A cognitive
decision code? A motor response code? Combining animal models, normal human studies,
and clinical evidence, the authors apply anatomical, physiological, and behavioral
perspectives to this question. The emerging view is that the corpus callosum
consists of many parallel interhemispheric channels for communication and control,
and that every transfer channel is context-dependent and modulated by
attention.