Brain Circuits and Functions of the Mind

The chemoaffinity hypothesis, developed by Sperry in the 1940s and 1950s, proposes that growing nerve fibers are guided to their correct targets by chemical markers, producing precise and specific neural connections . Several essays in Part I evaluate this theory's development and evidence. Levi-Montalcini traces its ontogenesis from 1963 to 1983; Hunt and Cowan provide an appreciation of Sperry's contributions to developmental biology; and Meyer reviews recent studies on retinotectal specificity . The volume treats chemoaffinity as Sperry's foundational contribution to developmental neurobiology, one that preceded and informed his later split-brain work.

Part II, 'Split-Brain Studies of Perception, Motor Coordination, and Learning in Cats and Monkeys, and Comparisons to Humans,' demonstrates the cross-species reach of Sperry's program. Berlucchi and Antonini examine the corpus callosum's role in visual field representation; Preilowski studies intermanual transfer and handedness; Hamilton reviews hemispheric specialization in monkeys; and Mishkin and Phillips trace a corticolimbic memory pathway . These essays show that the principles Sperry identified in cats and monkeys—hemispheric independence, callosal transfer, functional specialization—provided the experimental foundation for interpreting human commissurotomy patients.

Part III, 'Cerebral Hemispheres and Human Consciousness,' collects ten essays on the implications of hemispheric independence. Bogen discusses partial hemispheric independence with intact neocommissures; Levy addresses perception in the asymmetric brain; Zaidel examines long-term semantic memory in the two hemispheres; and Sperry himself contributes a concluding essay on forebrain commissurotomy and conscious awareness . The section illustrates how the split-brain paradigm generated a wide range of research questions about attention, memory, reading, and the neural basis of consciousness that extended well beyond Sperry's own experiments.

The book's organization mirrors Sperry's career arc. Part I opens with the chemoaffinity theory and developmental neurobiology—the work that established his reputation in the 1940s and 1950s. Part II moves to split-brain studies in animals, the experimental bridge between development and cognition. Part III culminates in hemispheric specialization and human consciousness, the work for which he received the 1981 Nobel Prize . This structure, outlined by editor Colwyn Trevarthen, presents Sperry not as a specialist in one area but as a scientist whose questions about how brain circuits specify their connections led him to the most difficult problems of mind and awareness .

The volume includes two appendices: a complete list of Sperry's publications and a roster of his students and collaborators . This apparatus makes the Festschrift a documentary resource for historians of neuroscience, showing the institutional and intellectual network that formed around Sperry's laboratory at Caltech. Contributors include Levi-Montalcini (who won her own Nobel Prize in 1986), Bogen (Sperry's clinical collaborator on the split-brain patients), and Trevarthen (who worked on hemispheric development) . The appendices demonstrate that Sperry's influence operated through a generation of researchers who extended his questions into new domains.

The Festschrift focuses on Sperry's experimental and theoretical contributions to neuroscience, not his later metaphysical and ethical writings. Sperry's concluding essay addresses conscious awareness in relation to commissurotomy, but the volume does not engage with his emergent mentalism or his proposals for a science of values . The essays treat his scientific legacy—chemoaffinity, split-brain research, and hemispheric specialization—as the primary subject. Readers interested in his philosophical positions should consult Science and Moral Priority (1983) directly; this volume provides the scientific foundation from which those positions were extrapolated.