The function of the so-called motor area of the brain / by Sir Victor Horsley.

  • Victor Horsley
Date:
1909
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Licence: Public Domain Mark

Credit: The function of the so-called motor area of the brain / by Sir Victor Horsley. Source: Wellcome Collection.

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    afferent impulse, and we are not reduced to interpreting motor responses which in a large number of cases are of subcortical origin. The evidence I possess on the question would seem to show that the conscious appreciation of pain in the upper limb is partly represented in the post-central gyrus. Thus, when the temporary symptoms after the removal of the pre-central gyrus had passed off, the conscious appreciation of a point as a painful prick was found to be preserved, and yet after the free removal or destruction of the whole arm centre—that is, of both central gyri—it is notably diminished, though, like all forms of sensation, not totally abolished.* The second point of evidence lies in the very interesting fact that the localization of a painful impulse is topognostically the Same as the sense of touch—that, in fact, the diminution in appreciation of a pin-prick is similarly subject to a proximal error, exactly as a light touch is. Inasmuch as the reaction of the person to the stimulus, whether tactile or painful, involves conscious appreciation, we can only conclude that a precisely similar cortical mechanism provides for this particular functional activity—that is, that pain is considerably represented in the Rolandic gyri. SUMMARY. 1. The so-called motor area of the human cortex cerebri is really sensori-motor. 2. The gyrus pre-centralis is in man the seat of representation of (1) slight tactility, (2) topognosis, (3) muscular sense, (4) arthric sense, (5) stereognosis, (6) pain, (7) move- ment. 3. The gyrus post-centralis is in man part of the arm area in which the sensori-motor representation is of the same kind as that in the gyrus pre-centralis, but in it probably provision for sensorial co-ordination is greater, and that for efferent impulses less. 4. The giant pyramids or Betz cells are not essential for the performance of purposive or voluntary movements. 5. Purposive or voluntary movements can be performed after complete removal of the corresponding part of the gyrus pre-centralis. INDEX OF PAPERS QUOTED. 1844, 1 Puchelt: Medicinischen Annalen. 1844. Bd.4,s.485. 2 Volkmann: (Wagner’s) Handwirterbuch der Physi- ologie. 1844. Bd. 11, s. 571. 1869. 8 Bastian: On the Muscular Sense, etc. BRITISH MEDICAL JOURNAL, 1869. 1870. 4 Hitzig u. Fritsch: Archiv fiir Anatomie wu. Physi- ologie. 1870. Heft 3. 1876. 5 Ferrier: The Functions of the Brain. London. First edition. 1876. Fig. 28, p. 142. 1878. 6 Lewis, Bevan: Proc. Roy. Soc, (with H. Clarke) and Brain. 1878-9. Vol. i, p. 79. 1881. 7Munk: Ueber die Functionen der Grosshirnrinde. 1881. 1884. 8 Hoffmann: Deutsches Archiv fiir klinische Medizin. 1884. Bd. 35, s. 529, and Bd. 36, s. 130, 9 Horsley: Consensual Movements as Aids in Diagnosis of Diseases of the Cortex Cerebri. Medical Times, 1884. of closed compartments, I would point out here that not only do the above observations show that the gyrus post-centralis is not the only part of the cortex in which pain is appreciated, but it is clear that a painful stimulus reaching the thalamus may be radiated to any perceptive sensory area—for example, the gyrus pre-centralis, or any other region of the cortex—and so arouse consciousness of the distress.
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