ARTIFICIAL EXCITATION OF CORTEX CEREBRI, 705 



origin ; or, secondary, resulting from disuse of portions of the lower 

 centres, in consequence of the lesion. The secondary changes are best 

 observed when the lesion is performed in young animals, and may not 

 show themselves at all in the adult. 



The parts which are primarily degenerated or atrophied after removal of the 

 whole cerebral cortex are the fibres of the pyramidal tract along their whole 

 course ; fibres passing between the optic thalamus and the cortex ; many of the 

 cells of the thalamus and of the corpus Luysii ; and many of the cells of the 

 substantia nigra of the mesencephalon, all upon the same side of the brain. 

 Degenerations also cross in the corpus callosum to the cortex of the opposite 

 hemisphere, but how far the cells of that hemisphere are involved has not been 

 ascertained. Secondarily, partial atrophy may be produced in the grey matter 

 of the pons Varolii, in the quadrigeminal bodies, in the fillet, and in the red 

 nucleus of the same side ; and in the inferior and middle cerebellar peduncles, 

 the hemisphere of the cerebellum, in the arciform fibres, and the nuclei of the 

 posterior columns of the medulla oblongata of the opposite side. 1 



THE KESULTS OBTAINED FROM ARTIFICIAL EXCITATION OF THF; 

 CORTEX CEREBRI. 



Previously to 1870, it was almost universally held that the cortex 

 cerebri could not be excited artificially, that there was no localisation 

 of particular functions in particular parts, that the cortex must act for 

 each and all of its functions as a whole, and that lesions of the cortex 

 produce, according to their extent, only a general depression of the 

 functions of the cerebrum without special symptoms of local paresis. 2 

 This doctrine was supposed to be firmly established by the experiments 

 of Flourens, which led him to reject absolutely the localisation of 

 function which had been formulated on altogether insufficient evidence 

 by the phrenologists, and it remained for many years in almost 

 undisputed possession of the field. A notable exception had, however, to 

 be made, after it had been shown, by the masterly researches of Broca, 3 

 that one important function of the cerebrum, that of producing articulate 

 language, is intimately associated with the integrity of the posterior part 

 of the third frontal convolution of the left hemisphere of the brain, and 

 doubt had begun to be thrown upon the doctrine, at least in its rigid 

 acceptation, by Hughlings Jackson, 4 and by Bastian, 5 the former of whom 

 was led somewhat later, from the study of certain cases of epilepsy, 

 following lesions of the brain in man, to the conclusion that the symptoms 

 could best be explained by the assumption of functional localisations, the 

 epileptif orm contractions being regarded as the result of irritative lesions. 6 



1 See on this subject, Langley, Journ. P/iyaiol., Cambridge and London, 1890, vol. xi. 

 p. 606 ; Langley and Sherrington, ibid., 1884, vol. v. p. 49 ; Monakow, Arch. f. Psychiat., 

 Berlin, Bde. xii., xiv., xvi., xx., and xxvii. ; other references in J. Soury, "Le systeme 

 nerveux," p. 642 e,t seq. 



2 Flourens, "Recherches experimentales sur les proprie'tes et les fonctions du systeme 

 nerveux," Paris, 1842, p. 99; Longet, "Anat. et physiol. du systeme nerveux," Paris, 



1842, tome i. p. 644 ; Matteucci, "Traite des phenomenes electrophysiologiques," Paris, 



1843, p. 242; Budge, " Untersuch. ueber d. Nervensystem, " Frankfurt a/Main, 1842, 

 Heft 2, S. 362 ; Schiff, " Lehrbuch d. Physiologic," 1858, Bd. i. S. 362. 



3 "Sur la siege de la faculte du langage articule*," Bull. Soc. anat. de Paris, 1861. 



4 London Hosp. Rep., 1864, vol. i. p. 459. 



5 "On the Localisation of Function in the Cerebral Hemispheres," Journ. Ment. Se., 

 London, Jan. 1869. 



6 "A Study of Convulsions," St. Andrews Med. Grad. Assoc. Trans., London, 1870, 

 vol. iii. 



VOL. II. 45 





