722 THE CEREBRAL CORTEX. 



after severance of the brain from the spinal cord : the action cannot, 

 therefore, be only upon the cortex. 1 



Fran^ois-Franck and Pitres (Figs. 328, 329) found that during an 

 epileptiform attack in dogs, the blood pressure, which was raised during 

 the excitation of the motor cortex which produced the attack, remained 

 high, with irregular elevations and depressions as long as the fit lasted ; 

 while the pulse rate, which first rose a little and then fell considerably 

 as the immediate result of the stimulation, rapidly mounted up during 

 the commencement of the epileptoid attack until it was far above the 

 normal rate, and again fell gradually during the clonic phase. The rise 

 of blood pressure is independent of the pulse rate, and depends upon an 

 active constriction of arterioles. There is usually a considerable post- 

 epileptic fall of blood pressure, and such a fall occasionally happens 

 during the clonic phase of an attack. 2 



The effects upon respiration vary with the severity of the attack. 

 In some cases the respiratory movements take on a clonic convulsive 

 character, even during the tonic phase of the attack; in other cases 

 they are altogether suspended during this phase, the thorax assuming an 

 expiratory attitude ; this condition being succeeded by one in which the 

 respiratory movements are of a clonic and convulsive character. 



The pupil usually dilates widely and remains dilated until near the 

 end of the attack, the secretion of saliva is increased, the excitation 

 operating through the chorda tyinpani, 3 and occurring principally in the 

 clonic phase, 4 and a secretion of sweat has also been noticed during an 

 attack. The effects upon other viscera are probably wide-spread, but 

 have not as yet been sufficiently studied experimentally. 



SPECIAL LOCALISATIONS IN THE CORTEX CEREBRI. 

 THE MOTOR AREAS AND CENTRES OF THE CEREBRAL CORTEX. 



The terms " motor area " and " motor centre " are here used to imply 

 those portions of the cerebral cortex which are directly connected 

 by efferent projection fibres with the lower level centres (spinal 

 cord, 5 bulb and midbrain) from which impulses producing voluntary 

 muscular action emanate. The use of the term "motor" for these 

 regions does not necessarily exclude the possession in the same part of 

 the cortex of some sort of conscious sensation, and especially of that 

 which is known as the muscular sense, although, as we shall presently 

 see, it is uncertain if this portion of the cortex actually does form part of 

 the sensorium. But it is certain that the region in question is in- 

 timately connected with, and its integrity is essential for, the production 

 of voluntary movements ; nervous impulses for the production of these 

 movements undoubtedly emanating from some of the cells in that 

 region, which, as shown by Betz and Bevan Lewis, are characterised by 



1 It was found by Horsley and myself (Journ. Physiol., Cambridge and London, 

 vol. vii. p. 103) that an after-effect is very occasionally seen to succeed prolonged or strong 

 excitation of the cut spinal cord, which is similar in its character to the epileptoid spasms 

 produced by excitation of the cortex cerebri, and which, like those spasms, may be preceded 

 by a tonic phase (see tig. 6 B, plate v. , loc. cit. ). 



2 Fransois-Franck, loc. cit., p. 199. 



3 Albertoni, "Papers from the Sienna Laboratory of Physiology," 1876. 



4 Francois- Franck and Pitres, loc. cit. 



5 Termed also on this account the " cord-area " of the cortex by Sherrington, Journ. 

 Physiol., Cambridge and London, 1885, vol. vi. p. 178 ; 1889, vol. x. p. 429. 



