The Parallel Brain

The Cognitive Neuroscience of the Corpus Callosum

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.

Table of Contents

  1. Preface
  2. Introduction: Poffenberger's Simple Reaction Time Paradigm for Measuring Interhemispheric Transfer Time

    Eran Zaidel and Marco Iacoboni

  3. I. Anatomy and Morphometry of the Corpus Callosum
  4. 1. Callosal Axons and Their Development

    Giorgio M. Innocenti and Raymond Bressoud

  5. 2. Corpus Callosum Morphology in Relation to Cerebral Asymmetries in the Postmortem Human

    Francisco Aboitiz, Andrés Idem and Ricardo Olivares

  6. 3. Brain Size: A Possible Source of Interindividual Variability in Corpus Callosum Morphology

    Lutz Jäncke and Helmuth Steinmetz

  7. 4. Morphometrics for Callosal Shape Studies

    Fred L. Bookstein

  8. 5. Mapping Structural Alterations of the Corpus Callosum During Brain Development and Degeneration

    Fred L. Bookstein

  9. II. Physiological Aspects of Callosal Sensorimotor Integration
  10. 6. Functions of the Corpus Callosum as Derived from Split-Chiasm Studies in Cats

    Maurice Ptito

  11. 7. Functions of the Corpus Callosum as Derived from Split-Chiasm Studies in Cats

    Maurice Ptito

  12. 8. Interhemispheric Visuomotor Activiation: Spatiotemporal Electrophysiology Related to Reaction Time

    Maurice Ptito

  13. III. Interhemispheric Sensorimotor Integration: Behavioral Studies
  14. 9. The Evolution of the Concept of Interhemispheric Relay Time

    Claude M. J. Braun, André Achim, and Caroline Larocque

  15. 10. The Corpus Callosum Equilibrates Hemispheric Activation

    Marcel Kinsbourne

  16. 11. Effects of Partial Callosal and Unilateral Cortical Lesions on Interhemispheric Transfer

    Carlo A. Marzi, L. G. Bongiovanni, Carlo Miniussi, and Nicola Smania

  17. 12. Stable and Variable Aspects of Callosal Channels: Lessons from Partial Disconnection

    Marco Iacoboni and Eran Zaidel

  18. 13. Sensorimotor Integration in the Split Brain

    Eran Zaidel and Marco Iacoboni

  19. 14. Parallel Processin the the Bisected Brain: Implications for Callosal Function

    Patricia A. Reuter-Lorenz

  20. 15. Agenesis of the Corpus Callosum

    Maryse C. Lassonde, Hannelore C. Sauerwein, and Franco Lepore

  21. IV. The Corpus Callosum and Clinical Investigations
  22. 16. Clinical Neuropsychological Assessment of Callosal Dysfunction: Multiple Sclerosis and Dyslexia

    Maryse C. Lassonde, Hannelore C. Sauerwein, and Franco Lepore

  23. 17. Alexithymia as a Consequence of Impaired Callosal Function: Evidence from Multiple Sclerosis Patients and Normal Individuals

    Géraldine Daquin, Jean Pelletier, Michele Montreuil, and Fabrice Robichon

  24. 18. Functional Consequences of Changes in Callosal Area in Tourette's Syndrome and Attention Deficit/Hyperactivity Disorder

    Maryse C. Lassonde, Hannelore C. Sauerwein, and Franco Lepore

  25. 19. Using the Corpus Callosum as an Effective Anatomical Probe in the Study of Schizophrenia

    Patricia E. Cowell, Victor Denenberg, Gary Boehm, Andrew Kertesz, and Henry Nasrallah

  26. 20. Interhemispheric Abnormalities in Schizophrenia and Their Possible Etiology

    Robert W. Doty

  27. V. From Anatomy to Behavior: The Case of Pure Alexia
  28. 21. The Role of Homotopic and Heterotopic Callosal Connections in Humans

    Stephanie Clarke

  29. 22. Optic Aphasia and Pure Alexia: Contribution of Callosal Disconnection Syndromes to the Study of Lexical and Semantic Representation in the Right Hemisphere

    Claudio G. Luzzatti

  30. About the Authors
  31. Contributors
  32. Author Index
  33. Subject Index