754 



MOVEMENTS OF CORTICAL ORIGIN. [Book in. 



cation current or current of rest, § 64) whenever the motor area 

 of the hind limb is stimulated, but not when other parts of the 

 cortex are stimulated. We have already said that stimulation 

 of any part of the motor region may under abnormal conditions 

 give rise to general epileptiform convulsions ; when these occur 

 during such an experiment as the above, currents of action mani- 

 fest themselves in the lower dorsal cord, whether the stimulation 

 giving rise to the convulsions be applied to the area for the hind 

 limb or to any part of the motor region. It has been further 

 observed that the currents of action developed within the spinal 

 cord tally in a very exact manner with the muscular movements. 

 The convulsions begin with a sustained ' tonic ' contraction of 

 the muscles, and the electrometer shews a similar sustained cur- 

 rent of actio)! ; this is followed by rhythmic movements of the 



Fig. 129. Through the Fore Part of the Pons. (Sherrington.) 

 (In the line 113, Fig. 108.) 



Py. Pyramidal fibres. F. G. Fibres from the frontal cortex. S. P. Superior 

 Peduncle of the cerebellum. F. m. median portion, F. I. lateral portion of the 

 Fillet. I. posterior longitudinal bundles. P. C. Q. Posterior corpora quadri- 

 gemina. y. Fibres which become detached from the Fillet, and further forward 

 from (the innermost) part of the Pes of the Crus. I. c. locus caeruleus. n. P. Q. 

 nucleus of the posterior corpora quadrigemina ; the outline is made too sharp. 

 IV. bundles of the fourth nerve decussating, IV. n. its nucleus. V. d. descending 

 root of the fifth nerve. Aq. the aqueduct, c. g. the region of central grey matter. 



muscles, accompanied by corresponding rhythmic movements of 

 the mercury of the electrometer. Without insisting too much 

 on the exact interpretation of these results we may take them as 

 at least shewing that, when the motor region of the cortex is 



