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This book is devoted to the description of agenesis of the corpus callosum, a congenital malformation of midline structures in the brain that may be regarded as a natural model of the "split-brain. " First reported by Rei! in 1812, this anomaly has since been described by several investigators. Interest in this malformation was revived in the 1970s by studies of interhemispheric transfer in Bogen and Vogel's commissurotomized patients and the subsequent findings by Sperry that acallosal patients were devoid of the typical disconnection deficits found in patients with surgical transection of the corpus callosum. Since this seminal work, the bulk of neuropsychological research on callosal agenesis has focused on the particulars of interhemispheric transfer and integration. An ever-growing literature has emerged on the subject, attempting to specify the extent and limits of neural plasticity in a nervous system that has evolved in the absence of the most important interhemispheric pathway. Whilst callosal agenesis proves to be an excellent model of cerebral plasticity, it has to be pointed out that this anomaly is often associated with other malformations and neurological diseases that may result in different degrees of mental retardation or other cognitive and sensorimotor deficits. In this context, neurological research on callosal agenesis has concentrated on the description of various syndromes associated with this pathology as well as on the attempt to specify its neurobehavioral manifestations.
List of contents
I: Neuroclinical Findings.- A. Clinical Description and Related Disorders.- Callosal Agenesis: Review of Clinical, Pathological and Cytogenetic Features.- The Aicardi Syndrome.- The Andermann Syndrome.- The Andermann Syndrome: Agenesis of the Corpus Callosum and Sensorimotor Neuropathy.- The Pathology of the Andermann Syndrome.- Genetic Studies of the Andermann Syndrome.- A New Syndrome: Familial Fronto-Nasal Dermoid Cysts with Agenesis of the Corpus Callosum.- Other Syndromes Frequently Associated with Callosal Agenesis.- B. Neuroradiological Characteristics.- Antenatal Sonographic Findings of Agenesis of the Corpus Callosum.- Callosal Agenesis: Postnatal Sonographic Findings.- CT Findings in Callosal Agenesis.- Magnetic Resonance Imaging of Corpus Callosum Dysgenesis.- C. Sleep Patterns.- Coherence Patterns of Infant Sleep EEG in the Absence of the Corpus Callosum.- Sleep, Dreaming and EEG Coherence Patterns in Agenesis of the Corpus Callosum: Comparisons with Callosotomy Patients.- II: Animal Models.- Aspects of Dendritic Maturation of Callosally Projecting Neurons.- Defects of the Fetal Forebrain in Acallosal Mice.- Pattern of Interhemispheric Connections in Mice with Congenital Deficiencies of the Corpus Callosum.- Three Different Animal Models of Early Callosal Defects: Morphological and Behavioral Studies.- III: Neuropsychological Description.- A. Sensory and Sensorimotor Functions.- Midline Sensory Integration in Callosal Agenesis.- Visual Integration in Callosal Agenesis.- The Development of Interhemispheric Transfer of Tactile Information in Cases of Callosal Agenesis.- Short- and Middle-Latency Somatosensory Evoked Potentials in Callosal Agenesis.- Motor Coordination in Callosal Agenesis.- B. Cognitive Functions.- Cognitive Functioning in Callosal Agenesis.-The Behavioral and Developmental Consequences of Callosal Agenesis and Aicardi Syndrome.- Auditory Verbal Learning and Memory in Cases of Callosal Agenesis.- Sounds and Shapes: Language and Spatial Cognition in Callosal Agenesis.- Disconnection Syndrome in Callosal Agenesis.- IV.- Callosal Agenesis - A Natural Split-Brain: Overview.- Contributors.
Summary
Proceedings of an International Brain Research Organization Satellite Symposium held in Quebec City, Canada, August 10-13, 1991
