An American text-book of physiology . e olfactory area at the tip of the temporal (Horsley). (J8G ^liV AMERICAN TEXT-BOOK OF PHYSIOLOGY. witliiu Mliicli all the impulses from a given seuse-orgau reach the areas in turu may be marked off into centres, formed by the groups ofcells which, for example, control the smaller masses of muscle belonging to agiven segment of a limb, or in the visual area are represented by those cellsespecially connected with one part of the retina. There is thus a motor regionthe stimulation of which gives rise to the more evident bodily th
An American text-book of physiology . e olfactory area at the tip of the temporal (Horsley). (J8G ^liV AMERICAN TEXT-BOOK OF PHYSIOLOGY. witliiu Mliicli all the impulses from a given seuse-orgau reach the areas in turu may be marked off into centres, formed by the groups ofcells which, for example, control the smaller masses of muscle belonging to agiven segment of a limb, or in the visual area are represented by those cellsespecially connected with one part of the retina. There is thus a motor regionthe stimulation of which gives rise to the more evident bodily this are several subdivisions, the stimulation of one of which is fol-lowed by movements of groups of muscles—for instance, those controlling thearm—and within such an area in turu come the smaller centres, or thosethe stimulation of which is first followed by movements at one joint only. Another method of studying the cortex is to regard the character of themovement obtained by stimulating a single area, as that of the arm. Figure. Fig. 186.—Showing in the arm-area (monkeys brain) the localization of movements havingdifferent characters (after Horsley). 186 shows that stimulation of the upper arm-area gives rise in the first in-stance to movements of extension, whereas the lower arm-area yields those offlexion. This basis of subdivision is, however, not so useful as the analysisinto centres. As the smallest subdivisions, the centres are most convenientfor further study. If a vertical incision be carried around such a centre so as to isolate it fromthe other parts of the cortex, the characteristic reactions still follow the stimu-lation of it, indicating that tiie special effect can be produced l)y the passageof impulses from the point of stimulation toward the infracortical , in addition, a cut be made below the cortex and parallel with its surface,then stimulation of the cortex above this section is ineffective, thus indicatingthat the impulses pass from the
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Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
