CHAPTER XXXI 



Central control of receptors 

 and sensory transmission systems 



ROBERT B. LIVINGSTON 



National Institute oj Menial Health and National Institute of Neurological 

 Diseases and Blindness, National Institutes of Health, Bethesda, Maryland 



CHAPTER CONTENTS 



Control of Receptor Acti\ ity 



Sympathetic Influence on Touch Receptors 



Efferent Control of Invertebrate Stretch Receptors 



Efferent Control of Mammalian Stretch Receptors 



Remote Central Control of Stretch Receptors 

 Control of Activity in Special Sense Afferents 



Auditory Nerve Activity 



Optic Nerve Activity 



Olfactory Bulb Activity 

 Control of Central Sensory Relays 



Spinal Ascending Relays 



Dorsal Column and Other Bulbar Relays 



Thalamic Relays 

 Cephalic Interaction Systems 



Corticipetal Projection Systems 



Cortical Interaction Systems 



Corticifugal Influences on Brain-Stem Mechanisms 



Organization of Centrifugal Sensory Control Mechanisms 



Transactional Mechanisms Relating to Sensory Control 

 Systems 

 Sensory Attention, Habituation and Conditioning 



Auditory Habituation 



Auditory Conditioning 



Shifts of Attention 



Visual Responses 



Beha\ior and Neurophysiology 

 Interpretations 

 Summary 



IT IS A VER"!' OLD NOTION, which needs often to be 

 repeated, that our sensory pathways are subject to 

 error and hence may yield distorted sensations. This 

 idea was succinctly stated three centuries ago by 



Descartes,' in point of fact, these essentially neuro- 

 physiological considerations provided the cornerstone 

 of his philosophy of universal doubt. Nonetheless, 

 little attention has been given to the possibility that 

 the central nervous system may itself be able to 

 exercise some measure of direct control over the 

 traffic of nerve impulses ascending sensory pathways. 



Recent experimental evidence indicates that such 

 central influences do exist and can modify sensory 

 input patterns all the way from receptors to whate\er 

 end point is chosen — from peripheral sense organs to 

 at least the sensory cortex. Much additional study 

 needs to be given to particular features of this mech- 

 anism, but already the implications are far-reaching. 



Sensory impulses can apparently be interfered with 

 at their point of origin and at synaptic junctions as a 

 result of activity taking place in certain remote parts 



' "I have learned from some persons whose arms or legs have 

 been cut off, that they sometimes seemed to feel pain in the part 

 which had been amputated, which made me think I could not 

 be quite confident that it was a certain member which pained 

 me, even although I felt pain in it. . . . In the same way, when 

 I feel pain in my foot, my knowledge of physics teaches me that 

 this sensation is communicated by means of ner\es dispersed 

 through the foot, which being extended like cords from there 

 to the brain, when they are affected in the foot, at the same time 

 affect the inmost portion of the brain which is their extremity 

 and place of origin, and there excite a sensation of pain repre- 

 sented as existing in the foot. ... If there is any cause which 

 excites, not in the foot but in some part of the ner\es which are 

 extended between the foot and the brain, or even in the brain 

 itself, the same action which usually is produced when the foot 

 is detrimentally affected, pain will be experienced as though it 

 were in the foot." Rene Descartes, Discourse on Method, 1637. 



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