Cerebral Cortex Vol. 5 : Sensory-Motor Areas and Aspects of Cortical Connectivity

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.