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STUDIES IN THE REFLEXES OF THE GUINEA‐PIG. III.: THE EFFECT OF REMOVAL OF THE CORTEX OF ONE CEREBRAL HEMISPHERE
Author(s) -
Brown T. Graham
Publication year - 1910
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0370-2901
DOI - 10.1113/expphysiol.1910.sp000061
Subject(s) - reflex , anatomy , lesion , stimulus (psychology) , cerebral cortex , spinal cord , hindlimb , cortex (anatomy) , medicine , neuroscience , psychology , anesthesia , surgery , psychotherapist
1. In certain of the reactions of the hind limb of the normal guinea‐pig to similar stimuli applied to the same points of the skin there is a possibility of two different reactions (flexion and extension). 2. After removal of the cortex of one cerebral hemisphere the reactions of the guinea‐pig to mechanical stimuli applied to symmetrical points differ on the two sides. 3. Where such difference is seen, that on the crossed side is one of extension. The best example of this is the “extension reaction” obtained by a mechanical stimulus applied to the skin of the side of the thorax just behind the caudal border of the scapula. 4. The reaction on the uncrossed side is one of flexion. This is best seen in the “scratch reaction” obtained by stimulating in the same way the corresponding area on the side of the lesion. 5. Both these reactions may persist for at least 66 weeks after the production of the lesion. 6. The presence of these reactions is probably due to raised reflex excitability of the spinal cord—on the one side to an exaltation of flexion reflex excitability, on the other to one of extension reflex excitability. The production of these two opposite reactions by a unilateral cortical lesion may be connected with the normal alternation of movements in the hind limbs of the guinea‐pig as seen in the movements of trotting. 7. That flexion reflex excitability is raised upon the same side of the spinal cord as the lesion is further shewn by the reactions in the “anæsthetic scratch when produced in these guinea‐pigs. The movements in this state are similar to those of the scratch‐reflex, and are found to be greater on the side of the lesion. In some cases they are confined to that side.