THE MOTOR CORTICAL CENTERS OF THE CEREBRUM. 783 



caused retraction and elevation of the angle of the mouth, with partial opening 

 of the mouth. On stimulation of b Ferrier observed opening of the mouth, with 

 protrusion and retraction of the tongue (bilateral action !) , the dog not rarely 

 making barking sounds. He designates this area the mouth-center. Stimulation 

 of c c causes retraction of the angle of the mouth by the platysma, stimulation 

 of c' elevation of the angle of the mouth and of the side of the face to the point 

 of closing the eye (the same as at 9). On stimulation of the middle e opening 

 of the eye and dilatation of the pupil result, the eyes and the head being rotated 

 toward the opposite side. Stimulation of the postcruciate gyrus causes contraction 

 of the perineal muscles. Stimulation of the anterior declivous surface of the 

 precruciate gyrus causes movements of the pharynx and the larynx. Stimulation 

 of a definite point in the anterior half of the foot of the ascending frontal convo- 

 lution (in the ape) gives rise to contraction of the glottis, as in phonation. Stimu- 

 lation anteriorly and exteriorly to the center for the extremities (in the rabbit) 

 causes movements of mastication and deglutition. 



Observations on the ape showed likewise a strict localization of the centers. 

 The movement caused by stimulation with induction-currents proved similar to 

 those executed voluntarily. Rarely a single muscle contracted; generally a co- 

 ordinated group. The antagonists are at times thrown into activity, in so far as 

 the primary movement may be followed by that of the antagonists. The contrac- 

 tion exhibits an oscillatory rhythm of from ten to fifteen movements in one second. 



On more marked irritation, in addition to the muscles of the opposite 

 side, those of the same side may be made to contract, the irritation 

 extending to the other side. Muscles such as those of the eyes, the peri- 

 neum, the larynx, the pharynx, the muscles of mastication, that are 

 moved on both sides at the same time, appear to have a center not only 

 in the opposite hemisphere, but also in that on the same side. The 

 question is of great practical significance from a diagnostic standpoint 

 whether movements cannot be excited by irritation due to local disease, 

 such as inflammation, tumor, degenerative processes, and the like, in- 

 volving the motor areas in the brain of man. Hughlings-Jackson answers 

 this question in the affirmative, and explains in this manner the occur- 

 rence of unilateral, localized epileptiform convulsions, which Ferrier 

 and Landois observed as a result of inflammatory irritation. By means 

 of marked irritation of the motor areas a complete general convulsive 

 epileptic attack can be induced in dogs. 



This begins with twitchings in the specially related group of muscles, passes 

 then to the corresponding member of the opposite side and involves the entire 

 musculature of the body, at first in clonic, then in tonic, and finally again in clonic 

 spasms. Above the internal capsule feeble irritation is often sufficient to excite 

 this form of epilepsy. The opposite side of the body has also been observed to 

 be involved in convulsions, and from below upward, after the movements had 

 been present in all parts on the side first affected. The spasmodic irritation 

 passes from center to center, and intervening motor areas are never skipped. 

 After a primary attack of such character, the slightest irritation is often sufficient 

 for the excitation of other epileptic attacks. During the attack the circulation 

 in the brain is accelerated and the vessels of the pia are dilated. As, at the same 

 time, also the intracranial pressure is greatly increased, Kocher has suggested 

 the making of a trephine-opening in the skull in epileptics and covering it only 

 with soft parts, in order in this way to provide to a certain degree a safety-valve. 

 With the object of preventing the variations in the fulness of the blood-vessels 

 that are observed in epileptic attacks the suggestion to extirpate the cervical 

 sympathetic in epileptics would appear justifiable. Perhaps it would be advisable 

 to ligate the cerebral carotid at the same time. 



The irritation of the centers appears to be followed by a brief state of lessened 

 irritability, the refractory period. Also irritation of the subcortical white matter 

 causes general convulsions, which, however, begin in the muscles of the same 

 side. 



If certain motor points are extirpated, the convulsions may be wanting in 

 the epileptic attack in the muscles controlled from these points. Severance of 



