Main description:

Volume 5 of Cerebral Cortex completes the sequence of three volumes on the individual functional areas of the cerebral cortex by covering the somatosensory and motor areas. However, the chapters on these areas lead naturally to a series of others on patterns of connectivity in the cortex, intracortical and subcortical, so that the volume as a whole achieves a much broader viewpoint. The individual chapters on the sensory-motor areas reflect the considerable diversity of interest within the field, for each of the authors has given his or her chapter a different emphasis, reflecting in part topical interest and in part the body of data resulting from work in a particular species. In considering the functional organization of the somatosensory cortex, Robert Dykes and Andre Ruest have chosen to concentrate on the nature of the mapping process and its significance. Harold Burton, in his chapter on the somatosensory fields buried in the sylvian fissure, shows how critical is an understanding of this mapping process in the functional subdivision of the cortex. A frequently overlooked subdivision of the cortex, the vestibular region, is given the emphasis it deserves in a chapter by John Fredrickson and Allan Rubin. The further functional subdivisions that occur within the first somatosensory area are given an anatom ical basis in the review by Edward Jones of connectivity in the primate sensory motor cortex.

Contents:

1 What Makes a Map in Somatosensory Cortex?.- 1. A Statement of the Problem.- 2. A History of Mapmaking in Somatosensory Cortex.- 3. Questions Currently of Interest.- 4. The Process of Mapping: Some Practical Considerations.- 5. Biological Mapping Functions.- 6. Reorganization following Deafferentation.- 7. Organization following Nerve Regeneration.- 7.1. Crushing Nerve Injuries.- 7.2. Transection and Repair.- 8. Other Clues to the Nature of Biological Mapping Functions.- 8.1. Interpretations of Map Variability.- 8.2. A Mechanism for Dynamic Control of Somatotopic Order.- 8.3. Intracortical Connectivity.- 9. Summary.- 10. References.- 2 Second Somatosensory Cortex and Related Areas.- 1. Introduction: A Problem of Definitions.- 2. Somatotopic Organization in SII.- 2.1. Orientation.- 2.2 Well-Differentiated Somatotopy.- 2.3. Distribution of Body Regions in the SII Map.- 2.4. Bilateral Receptive Fields.- 3. The Cytoarchitecture of SII.- 4. Thalamocortical Connections.- 4.1. Historical Background.- 4.2. Projections from the Ventrobasal Complex in Cats.- 4.3. Projections from Pars Caudalis of VPL and from VPM in Primates.- 4.4. Projections from VB in Rodents.- 4.5. Connections of the Posterior Complex.- 5. Corticocortical Connections.- 5.1. Intrinsic Connections.- 5.2. Extrinsic Connections with Somatosensory Cortex.- 5.3. Other Extrinsic Connections.- 5.4. Ipsilateral Cortical Connections of SIV.- 6. Corticofugal Connections.- 6.1. Corticospinal Projections.- 6.2. Corticobulbar Connections.- 6.3. Corticomesencephalic Projections.- 6.4. Corticopontine Connections.- 6.5. Physiological Effects of Stimulating SII and SIV.- 7. Physiological Responses.- 7.1. Physiological Characterization of SII Neurons.- 7.2. Physiological Characteristics of Neurons in SIV and Ri.- 7.3. Physiological Characteristics of Somatosensory Neurons in Area 7b of Primates.- 8. Lesion-Behavioral Studies.- 8.1. Studies with Primates.- 8.2. Studies with Cats and Dogs.- 9. Conclusions.- 10. References.- 3 Vestibular Corte.- 1. Introduction.- 2. Parietal Cortical Projections.- 3. SI Forelimb Field Projection.- 4. Convergence.- 5. The Ascending Pathway to the Cortex.- 6. Clinical Implications.- 7. References.- 4 Connectivity of the Primate Sensory-Motor Corte.- 1. Introduction.- 2. Thalamic Inputs.- 2.1. Lemniscal, Cerebellar, and Pallidal Components of the Thalamus.- 2.2. Representation in the Ventral Posterior Nuclei (VPL and VPM) and Ventral Lateral Posterior (VLp) Nucleus.- 3. Thalamocortical Connectivity.- 3.1. Maps of the Sensory-Motor and Adjacent Areas.- 3.2. Afferent Inputs to Sensory and Motor Cortical Maps.- 3.3. Lack of Thalamocortical Collateralization.- 3.4. The Question of SII.- 3.5. Finer Details of the Thalamocortical Projection to SI.- 4. Subcortical Connections.- 5. Corticocortical Connections.- 5.1. Ipsilateral Connections.- 5.2. Contralateral Connections.- 6. Conclusions.- 7. Abbreviations.- 8. References.- 5 Functions of Corticocortical Neurons of Somatosensory, Motor, and Parietal Cortex.- 1. Introduction.- 2. Properties of Corticocortical Neurons.- 2.1. Corticocortical Neurons Projecting to Motor Cortex.- 2.2. Other Identified Corticocortical Neurons.- 2.3. Summary.- 3. Effects of Corticocortical Neurons.- 3.1. Effects of SI upon Motor Cortex.- 3.2. Secondary Motor Areas.- 3.3. Effects of SI upon SII.- 3.4. Corticocortical Effects Compared to Other Inputs.- 3.5. Summary.- 4. What Information Is Carried by Corticocortical Neurons?.- 4.1. Parallel Pathways.- 4.2. Simultaneous Recordings from Interconnected Cortical Areas.- 4.3. Summary.- 5. Conclusions.- 6. References.- 6 Motor Cortex Output in Primates.- 1. Motor Cortex Neurons and ? Motoneurons.- 1.1. Classes of Motor Cortex Output Cells.- 1.2. Motor Cortex Activity during a Motoneuron Inactivity.- 1.3. Correlates of Neuronal Size.- 1.4. Cells Controlled by Pyramidal Tract Outputs.- 2. Movements of Hand and Jaw.- 2.1. Precision Grip versus Power Grip.- 2.2. Chewing versus Operantly Controlled Jaw Movement.- 2.3. Role of Sensory Input in Movements of Hand and Jaw.- 3. Transcortical Reflexes.- 3.1. Phillips's Concept of Match and Mismatch.- 3.2. Postural Stability and Micromovement.- 3.3. Set-Dependent Motor Cortex Responses.- 4. References.- 7 Motor Cortex of Rodents.- 1. Introduction.- 2. Cortical Field Definition in Rodent Motor Cortex.- 2.1. Cytoarchitecture of Frontal and Parietal Cortex.- 2.2. Correspondence between Cytoarchitecture and Electrophysiology.- 3. Input-Output Organization of Rat Motor Cortex.- 3.1. Topography of Rat Motor Cortex.- 3.2. Afferent Organization.- 3.3. Efferent Organization.- 4. Functional Specializations of Rodent Motor Cortex.- 4.1. The Importance of Motor Cortex to Rodents.- 4.2. Cortical and Efferent Pathway Damage.- 4.3. Neuronal Activity in Rodent Motor Cortex.- 4.4. Species Specialization in Motor Cortex Organization and Function.- 5. Conclusions.- 6. References.- 8 Termination of Thalamic Afferents in the Cerebral Cortex.- 1. Introduction.- 2. Thalamocortical Topography.- 3. Correlations of Cortical Physiology with Thalamocortical Projections.- 4. Neurons Postsynaptic to Thalamic Afferents.- 5. Quantitative Aspects of Thalmocortical Synaptic Relations.- 6. Synaptic Sequences Involving Neurons Postsynaptic to Thalamic Afferents.- 7. Conclusions.- 8. References.- 9 General Organization of Callosal Connections in the Cerebral Cortex.- 1. Introduction.- 2. The Callosal Neurons.- 2.1. Radial Distribution.- 2.2. Morphology.- 2.3. Synaptology.- 3. The Callosal Tract.- 4. The Termination of Callosal Axons.- 5. Corticotopic Organization of Callosal Connections.- 5.1. Area-to-Area Interrelations.- 5.2. Callosal Connections and Peripheral Representations: Visual Areas.- 5.3. The Fine Organization of Callosal Connections.- 5.4. Some Electrophysiological Correlates of Callosal Connections: Callosal Connections at the Cellular Level.- 6. Function of Callosal Connections.- 7. The Development of Callosal Connections.- 7.1. What Causes Cortical Neurons to Send an Axon through the Corpus Callosum?.- 7.2. What Directs Callosal Axons to a Given Area?.- 7.3. Factors Involved in the Elimination/Stabilization of Juvenile Callosal Connections.- 8. Conclusions.- 9. References.- 10 The Thalamic Intralaminar Nuclei and the Cerebral Cortex.- 1. Historical Introduction.- 2. Cytoarchitectonic Delimitation of the Intralaminar Nuclei, with Notes on Their Comparative Anatomy.- 3. The Intralaminar-Cortical Projections.- 3.1. Areal Organization.- 3.2. Laminar Organization.- 3.3. Axonal Branching.- 4. The Subcortical Efferents of the Intralaminar Nuclei.- 4.1. Interrelations between Intralaminar Projections to Caudate and Cortex.- 5. The Subcortical Afferents to the Intralaminar Nuclei.- 5.1. Intrathalamic Relationships between Intralaminar Afferents and Efferents.- 6. The Cortico-Intralaminar Projections.- 6.1. Cells of Origin.- 6.2. Areal Organization.- 6.3. Contralateral Projections.- 7. Functional Role of the Intralaminar System.- 7.1. The Intralaminar Nuclei and the Brain Stem Reticular Formation.- 7.2. The Intralaminar Nuclei and Intrathalamic Mechanisms.- 7.3. The Intralaminar Nuclei and Sensory-Motor Integration.- 7.4. Anatomic-Clinical Correlations.- 8. Conclusions.- 9. References.- 11 New Perspectives on the Organization and Evolution of Nonspecific Thalamocortical Projections.- 1. Historical Origins of the Term "Nonspecific Thalamus".- 2. A Tripartite Division of Thalamus Based on Cortical Layers of Termination.- 2.1. Specific Nuclei.- 2.2. Nonspecific Deep Layer-Projecting Nuclei.- 2.3. Nonspecific Layer I-Projecting Nuclei: The Paralaminar System.- 3. Evidence for a Paralaminar Layer I-Projecting System Demonstrated by Retrograde Tracing.- 4. Comparative Aspects of the Nonspecific Thalamocortical System.- 4.1. Generalized Mammals.- 4.2. Cats.- 4.3. Monkeys.- 5. Cellular Origins of Layer I Projections.- 6. Speculation on the Phylogeny of the Nonspecific Thalamus.- 6.1. The Intralaminar Nuclei.- 6.2. Layer I-Projecting Nuclei.- 7. Functional Considerations.- 7.1. Reticular Activation.- 7.2. Motor Activation.- 7.3. Sensory Activation.- 8. References.- 12 Topography of Corticostriatal Projections in Nonhuman Primates and Implications for Functional Parcellation of the Neostriatum.- 1. Introduction.- 2. Early Views of Corticostriatal Projections.- 3. New Topography of Corticostriatal Projections.- 4. Segregation of Cortical Terminal Fields in the Striatum: Double-Labeling Studies.- 5. Interdigitation of Cortical Terminal Fields in the Neostriatum.- 6. Neostriatal Compartments and Their Relationship to Corticostriatal Projections.- 7. Cortical Laminar Origin of the Striatal Projection.- 8. Implications for Neostriatal Function.- 9. Implications for Neurological Disease.- 10. References.- 13 The Claustrum and the Cerebral Cortex.- 1. Introduction.- 2. Location, Shape, and Cellular Composition of Claustrum.- 3. Development of Claustrum.- 4. Cortical Connections of Claustrum.- 4.1. Conclusions and Questions from Lesion Studies.- 4.2. Corticoclaustral Connections in the Cat.- 4.3. Corticoclaustral Connections in Rodents and the Rabbit.- 4.4. Corticoclaustral Connections in the Monkey and Other Primates.- 4.5 Contralateral Connections and Divergence in the Claustrocortical Pathway.- 4.6. Cortical Layers Connected with Claustrum.- 5. Subcortical Connections of Claustrum.- 6. Physiological Properties of Claustral Neurons.- 7. Visual Field Map in Claustrum.- 8. Function of Claustrum.- 9. References.