Page:Principles of Psychology (1890) v1.djvu/87

67 FUNCTIONS OF THE BRAIN. 67 be any consciousness pertaining to the lower centres, it is a consciousness of which the self knows nothing. THE RESTITUTION OP FUNCTION. Another problem, not so metaphysical, remains. The most general and striking fact connected with cortical in- jury is that of the restoration of function. Functions lost at first are after a few days or weeks restored. How are ive to understand this restitution ? Two theories are in the field : 1) Eestitution is due to the vicarious action either of the rest of the cortex or of centres lower down, acquiring func- tions which until then they had not performed ; 2) It is due to the remaining centres (whether cortical or 'lower') resuming functions which they had always had, but of which the wound had temporarily inhibited the exercise. This is the view of which Goltz and Brown- Sequard are the most distinguished defenders. Inhibition is a vera causa, of that there can be no doubt. The pneumogastric nerve inhibits the heart,, the splanch- nic inhibits the intestinal movements, and the superior laryngeal those of inspiration. The nerve-irritations which may inhibit the contraction of arterioles are innumerable, and reflex actions are often repressed by the simultaneous excitement of other sensory nerves. For all such facts the reader must consult the treatises on physiology. What concerns us here is the inhibition exerted by different parts of the nerve-centres, when irritated, on the activity of dis- tant parts. The flaccidity of a frog from ' shock,' for a minute or so after his medulla oblongata is cut, is an in- hibition from the seat of injury which quickly passes away. What is known as ' surgical shock ' (unconsciousness, pallor, dilatation of splanchnic blood-vessels, and general syncope and collapse) in the human subject is an inhibition which lasts a longer time. Goltz, Freusberg, and others, cutting the spinal cord in dogs, proved that there were functions inhibited still longer by the wound, but which re- established themselves ultimately if the animal was kept alive. The lumbar region of the cord was thus found to contain independent vaso-motor centres, centres for erec-