Callosal Agenesis : A Natural Split Brain?

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. Front Matter....Pages i-ix Callosal Agenesis: Review of Clinical, Pathological, and Cytogenetic Features....Pages 1-6 The Aicardi Syndrome....Pages 7-17 The Andermann Syndrome: Agenesis of the Corpus Callosum and Sensorimotor Neuropathy....Pages 19-26 The Pathology of the Andermann Syndrome....Pages 27-30 Genetic Studies of the Andermann Syndrome....Pages 31-38 A New Syndrome: Familial Fronto-Nasal Dermoid Cysts with Agenesis of the Corpus Callosum....Pages 39-53 Other Syndromes Frequently Associated with Callosal Agenesis....Pages 55-62 Antenatal Sonographic Findings of Agenesis of Corpus Callosum....Pages 63-67 Callosal Agenesis: Postnatal Sonographic Findings....Pages 69-76 CT Findings in Callosal Agenesis....Pages 77-82 Magnetic Resonance Imaging of Corpus Callosum Dysgenesis....Pages 83-95 Coherence Patterns of Infant Sleep EEG in Absence of the Corpus Callosum....Pages 97-108 Sleep, Dreaming and EEG Coherence Patterns in Agenesis of the Corpus Callosum: Comparisons with Callosotomy Patients....Pages 109-117 Aspects of Dendritic Maturation of Callosally Projecting Neurons....Pages 119-123 Defects of the Fetal Forebrain in Acallosal Mice....Pages 125-133 Pattern of Interhemispheric Connections in Mice with Congenital Deficiencies of the Corpus Callosum....Pages 135-146 Three Different Animal Models of Early Callosal Defects: Morphological and Behavioral Studies....Pages 147-154 Midline Sensory Integration in Callosal Agenesis....Pages 155-169 Visual Integration in Callosal Agenesis....Pages 171-183 The Development of Interhemispheric Transfer of Tactile Information in Cases of Callosal Agenesis....Pages 185-197 Short- and Middle-Latency Somatosensory Evoked Potentials in Callosal Agenesis....Pages 199-206 Motor Coordination in Callosal Agenesis....Pages 207-219 Cognitive Functioning in Callosal Agenesis....Pages 221-233 The Behavioral and Developmental Consequences of Corpus Callosal Agenesis and Aicardi Syndrome....Pages 235-246 Auditory Verbal Learning and Memory in Cases of Callosal Agenesis....Pages 247-260 Sounds and Shapes: Language and Spatial Cognition in Callosal Agenesis....Pages 261-273 Disconnection Syndrome in Callosal Agenesis....Pages 275-284 Callosal Agenesis — A Natural Split-Brain Overview....Pages 285-299 Back Matter....Pages 301-308