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.In lower animals this may not be so much the case.The traces of sightfound (supra, p.46) in dogs and monkeys whose occipital lobes were entirely destroyed, maypossibly have been due to the fact that the lower centres of these animals saw, and that what theysaw was not ejective but objective to the remaining cortex, i.e.it formed part of one and the sameinner world with the things which that cortex perceived.It may be, however, that the phenomenawere due to the fact that in these animals the cortical 'centres' for vision reach outside of theoccipital zone, and that destruction of the latter fails to remove them as completely as in man.This, as we know, is the opinion of the experimenters themselves.For practical purposes,nevertheless, and limiting the meaning of the word consciousness to the personal self of theindividual, we can pretty confidently answer the question prefixed to this paragraph by sayingthat the cortex is the sole organ of consciousness in man.[66] If there [p.67] be anyGet any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY35consciousness pertaining to the lower centres, it is a consciousness of which the self knowsnothing.THE RESTITUTION OF FUNCTION.Another problem, not so metaphysical, remains.The most general and striking fact connectedwith cortical injury is that of the restoration of function.Functions lost at first are after a fewdays or weeks restored.How are we to understand this restitution ?Two theories are in the field:1) Restitution is due to the vicarious action either of the rest of the cortex or of centres lowerdown, acquiring functions which until then they had not performed;2) It is due to the remaining centres (whether cortical or 'lower') resuming functions which theyhad always had, but of which the wound had temporarily inhibited the exercise.This is the viewof which Goltz and Brown-Séquard are the most distinguished defenders.Inhibition is a vera causa, of that there can be no doubt.The pneumogastric nerve inhibits theheart, the splanchnic inhibits the intestinal movements, and the superior laryngeal those ofinspiration.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 isthe inhibition exerted by different parts of the nerve-centres, when irritated, on the activity ofdistant parts.The flaccidity of a frog from 'shock,' for a minute or so after his medulla oblongatais cut, is an inhibition 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 alonger time.Goltz, Freusberg, and others, cutting the spinal cord in dogs, proved that there werefunctions inhibited still longer by the wound, but which reestablished themselves ultimately ifthe animal was kept alive.The lumbar region of the cord was thus found to contain independentvaso-motor centres, centres for erec-[p.68] tion, for control of the sphincters, etc., which could beexcited to activity by tactile stimuli and as readily reinhibited by others simultaneouslyapplied.[67] We may therefore plausibly suppose that the rapid reappearance of motility, vision,etc., after their first disappearance in consequence of a cortical mutilation, is due to the passingoff of inhibitions exerted by the irritated surface of the wound.The only question is whether allrestorations of function must be explained in this one simple way, or whether some part of themmay not be owing to the formation of entirely new paths in the remaining centres, by which theybecome 'educated' to duties which they did not originally possess.In favor of an indefiniteextension of the inhibition theory facts may be cited such as the following: In dogs whosedisturbances due to cortical lesion have disappeared, they may in consequence of some inner orouter accident reappear in all their intensity for 24 hours or so and then disappear again.[68] In adog made half blind by an operation, and then shut up in the dark, vision comes back just asquickly as in other similar dogs whose sight is exercised systematically every day.[69] A dogwhich has learned to beg before the operation recommences this practice quite spontaneously aGet any book for free on: www.Abika.com THE PRINCIPLES OF PSYCHOLOGY36week after a double-sided ablation of the motor zone
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