CHAPTER XXXIII 



Sensorimotor cortical activities 



C. A. TERZUOLO 

 W. R. ADEY 



School nj Medicine, University of California at Los Angeles, Los Angeles, California 



CHAPTER CONTENTS 



Compaiatix e Studies of Excitable Cerebral Cortex 



Phyletic Aspects of Cerebral Cortical Representation 



Ontogenetic Development of Motor Cortex 

 Cortical Stimulation Studies of Rolandic Motor Area 



Nature of Cortical Representations 



Autonomic Concomitants of Cortical Stimulation 

 Cortical Ablation Studies of Rolandic Motor Area 



Babinski Response 



Recovery After Ablation 

 Effects on Phasic and Tonic Muscular Activities of Stimulation 

 and Ablation of Cortical Areas Other Than Primary 

 Motor Area. Their Connections 



Supplementary Motor Areas 



Second Somatic Area 



Premotor Cortex (Area 6) 



Cingulate Gyrus 



Parietal, Occipital and Temporal Cortex 



Phenomenon of 'Suppression' 



Ablation Interfering With Total Motor Activity 



Motor and Sensory Functions Persisting After Hemispherec- 

 tomy 

 Major Afferents to Cortical Areas Concerned in Sensorimotor 

 Integration 



Thalamic Afferents 



Striopallidothalamocortical Interrelationships 



Ccrcbellocerebral Interrelationships 



Intra- and Intcrareal Connections of Ipsilatcral Hemisphere 



Callosal Interhemispheric Connections 

 Major Efferents From Cortical Areas Concerned in Sensori- 

 motor Integration 



Cortical Origin of Fibers of Pyramidal Tract 



Extent of frontal lobe contributions to pyramidal tract 

 Contribution of postcentral cortex to pyramidal tract 

 Evidence concerning pyramidal tract fibers arising in 

 temporal and occipital lobes 



Descending Connections of Pyramidal System 



Effects of stimulation and section of cerebi^al peduncle 

 Effect of section of rnedullary pyramid 

 Termination of pyramidal tract fibers in medulla 

 Effects of cerebral lesions in infancy on residual pyramidal 

 functions 



Sensorimotor Integration in Performance of Motor Activities 

 Role of Pyramidal System in Relation to Willed Movement 

 Studies of Conditioned Motor Performance 

 Parietal Lobe Influences on Motor Activity 

 Certain Corticosubcortical Interrelations in Motor Mecha- 

 nisms 



KNOWLEDGE OF THE PARTICIPATION of the Cerebral 

 cortex in sensory and motor activities has been 

 gleaned from both clinical and experimental obser- 

 vations. Shortly after the demonstration by Broca 

 of a center for speech in the cortex of the third frontal 

 convolution of the left hemisphere (6i), Hughlings 

 Jackson proposed a functional localization and repre- 

 sentation of movement in the cerebral cortex (217). 

 His suggestion proved true with the publication of 

 the work of Fritsch & Hitzig (158). These pioneers 

 demonstrated the excitability of the cerebral cortex 

 by means of electrical stimuli and showed by this 

 method that movements could be evoked from certain 

 areas of the cerebral cortex but not from others. 



Confirmation of these findings by numerous inves- 

 tigators (18, 40, 70, 143, 144, 153, 154, 211, 281-283, 

 339) soon extended the knowledge of cortical involve- 

 ment in sensorimotor activities (see 394, 448 for early 

 references). Before considering this problem in detail, 

 some of the difficulties encountered in the interpreta- 

 tion of data related to the subject should be fully 

 understood. 



Difficulties inherent in the use of anesthetics have 

 been largely overcome but others, and particularly 

 those related to the use of artificial stimulation, are 

 still of major importance. It is obvious, as has been 

 frequently remarked, that excitation elicited by means 

 of electric pulses may induce activities which are not 



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