. The story of the mind. Fig. 3.—Outer surface of left hemisphere of the brain (modifiedfrom Exner): a, fissure of Rolando • b^ fissure of Sylvius. travel on the same side, although in certain casesparallel impulses are also sent over to the otherhemisphere as well. For example, the very im-portant optic nerve, which is necessary to vision,comes from each eye separately in a large bunchof fibres, and divides at the base of the brain, sothat each eye sends impulses directly to the visualcentres of both hemispheres. THE CONNECTION OF BODY WITH MIND. Ill Of all the special questions which have ar
. The story of the mind. Fig. 3.—Outer surface of left hemisphere of the brain (modifiedfrom Exner): a, fissure of Rolando • b^ fissure of Sylvius. travel on the same side, although in certain casesparallel impulses are also sent over to the otherhemisphere as well. For example, the very im-portant optic nerve, which is necessary to vision,comes from each eye separately in a large bunchof fibres, and divides at the base of the brain, sothat each eye sends impulses directly to the visualcentres of both hemispheres. THE CONNECTION OF BODY WITH MIND. Ill Of all the special questions which have arisenabout the localization of functions in the nervoussystem, that of the function of certain areas knownas motor centres has been eagerly region on both sides of the fissure of Ro-lando in Fig. 3 contains a number of areas whichgive, when stimulated with electricity, very defi-nite and regular movements of certain muscles. Fig. 4.—Inner (mesial) surface of the right hemisphere of thebrain (modified from Schafer and Horsley). In both figuresthe shaded area is the motor zone. on the opposite side of the body. By careful ex-ploration of these areas the principal muscularcombinations—those for facial movements, neckmovements, movements of the arm, trunk, legs,tail, etc.—have been very precisely was concluded from these facts that these areaswere respectively the centres for the discharge ofthe nervous impulses running in each case to themuscles which were moved. The evidence re- 112 THE STORY OF THE MIND. cently forthcoming, however, is leading investi-gators to think that there is no cortical centre forthe motor or outgoing processes properly socalled, and that these Rolandic areas, althoughcalled ^ motor, are really centres for the mcom-ing reports of the movements of the respectivemuscles after the movements take place, and alsofor the preservation of the memories of movementwhich th
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