Pathologically this condition is designated as “irritable weakness;” an understanding of it is, as Maudsley shows, the foundation of the correct understanding of all the morbid states of the central organs of the nervous system. The loss of the normal proportion of stimulus and reaction is the sign of a morbid disorder; it is the simplest form of the “aberration” of the ganglion-cell. The “errant” ganglion-cell has no more force at its disposal than the healthy one, but it wastes the same in reacting on every feeble stimulus; it squanders it in tetanus.
The madness of little children and of the brutes (with the exception of those nearest to man) consists essentially in an aberration of the ganglion-cells of the medulla oblongata and spinal cord, in a disturbed grouping of the nerve elements in any cell, and in consequence thereof also in a disturbed co-ordination of the single central cell-groups. These are here no longer functional as a purposive physiological whole, but every group reacts tetanically on the small organic stimuli affecting it, which remain unnoticed in the healthy life, and thereby becomes incapable of retaining feeling with its neighbouring groups. The result is incoherent convulsions, as in St. Vitus’s dance. The convulsions may, however, also proceed from higher central points, which mediate the reflexes to sense-perception; then they stand in relation to actual or imaginary sense-perceptions, and manifest themselves as combative, destructive, or murderous impulse. Of this kind is the raging of a mad elephant, or the delirium of a maniac, who perceives the smell of sulphur in his nose, sees his supposed persecutors as devilish shapes surrounded with fiery flames, and believes he has to contend with them or an imaginary lion for his life.—Lastly, aberration in the sphere of conscious volition and ideation is an aberration of the ganglion-cells of the cerebral hemispheres; frenzy consists of spasmodic ideas and feelings, as St. Vitus’s dance consists of motor reflex convulsions.
It would be altogether wrong if one tried to see in the molecular disorder of the ganglion-cell, which squanders its store of energy in a manner disproportional to the stimuli, a condition of heightened power and capacity of execution; the morbidly degenerate irritability, in spite of its externally destructive effects, can only be interpreted as a symptom of weakness. Even the explosion of a steam-engine proves nothing with respect to the efficiency and solidity of the machine, but rather that it had a weak place. The elevated self-satisfaction and the extravagant merriment of an incipient maniac, or the delirium of a raving madman are just as little a proof of the strength and efficiency of the grey matter of their brains as the motor reflex convulsions of that of a spinal cord poisoned by strychnine; in both cases only the morbidly enhanced consumption of energy is revealed, and therefore the irritable weakness must in all cases draw after it torpid weakness. All mania ends in derangement of intellect or weakness of mind, all cramps in complete exhaustion of the organs concerned, or of the whole organism. The irritable weakness of the ganglion-cells spontaneously appearing in the organism is only the first stage of a process of degeneration, which is accelerated by irritability the more the increased consumption of energy coincides with an already diminished potential energy.—If we comprehensively consider wherein consists the difference between the nervous matter in the ganglion-cell and in the (alone active) axis cylinder of the nerve-fibre, it may be thus succinctly stated, that in the latter the chemical decomposition, in the former recomposition during functional repose preponderates (Wundt, p. 266). The former is evinced by this, that the nerve-fibre, abandoned to itself, i.e., separated from its province, has no power to maintain itself, but degenerates; the latter follows from this, that the ganglionic substance during functional repose not only repairs its own waste which it has suffered in the exercise of function, but also provides the nerve-fibres that spring from it with energy for defraying their expenditure. Thus, under normal circumstances, in the fibre the consumption of force, in the cell the production of force preponderates. If, now, the condition of irritable weakness occurs in the cell, not only is far more force consumed in all functional exercise, but also in consequence of the more frequent exercise of function the total duration of functional rest is diminished, when not (as in the maniacal, often deprived for weeks of sleep) reduced approximately to zero, and this, moreover, in a condition in which probably the capacity for chemical recomposition is diminished. In that case the occurrence of total exhaustion of the organism, and with a longer duration or more frequent recurrence of the attacks, the morphological and chemical degeneration of the nerve-centres is the necessary issue.
The stated fundamental distinction between the nervous matter in the ganglion-cell and that in the axis cylinder of the nerve-fibre is consequently, as is also shown by the occurrence of pathological degeneration in the grey nerve matter, not one of kind, but only of degree. Expenditure of energy takes place in the cell by decomposition, as well as storing up of energy in the fibre by recomposition, and only in the normal physiological condition of the organism is the opposite tendency predominant in either. Accordingly, in this gradual difference no reason can be found for a heterogeneity of substance in cell and fibre. The actions are, on the whole, similar in both, and the difference extends no further than the differentiation of a physiological organ into several subdivisions for the better fulfilment of modified purposes by more perfect division of labour. This result is important for the understanding of the truth that the psychical life does not cease with the ganglion-cell, but extends even to the nerve-fibre and beyond.
3. The Spinal Cord .—If we neglect the ganglion-cells united in the sympathetic plexus of nerves and dispersed in various organs, all the rest are massed in the grey matter of the spinal cord and brain. In the former the grey matter forms four united columns, of which those situated right and left correspond to the lateral halves of the body, whilst the two anterior ones are distinguished from the two posterior by the motor nerves issuing from the former, the sensory nerves from the latter. These four columns now are surrounded by an envelope of white nerve-matter, in which are collected the ascending sensory and the descending motor fibres.
From this it first of all results that there is no direct path to the higher nerve-centres for the nerves of the body issuing from the spinal cord, but that the same spot of the grey matter of the spinal cord from which the particular nerve springs must always be passed in centrifugal and centripetal conduction. In other words, the conducting fibres in the spinal cord are not directly, but only by the intervention of ganglionic cells, united with the nerves of the body; and in every conduction from the brain to the muscles or conversely, ganglionic cells of the spinal cord co-operate as active links, which reflectorially propagate the stimulus, so far as it lies for them above the threshold.
It further results from the above-named arrangement that sensory and motor fibres never spring simultaneously from one and the same ganglion-cell of the spinal cord; that thus a reflex from a sensory to a motor fibre is compounded of several separate reflexes of at least two ganglionic cells (one in the posterior and one in the anterior cornu). The simple reflexion in a single ganglion-cell of the spinal cord can always include only one kind of trunk-nerve, and the other term must consist of fibres connecting other ganglion-cells—be they neighbouring and co-ordinate, higher and superordinate or lower and subordinate cells—be it a plexus of primitive fibres connecting neighbouring cells, or an ascending or descending nerve-fibre. It is important to make clear this co-operation of several ganglionic cells of different functional importance in the occurrence of the simplest reflex of the spinal cord, in order thereby to open the way for a better comprehension of the entangled co-operation and subordination between the different central organs.
If the conducting fibres that run in the white substance of the spinal cord always remained on the same side on which they arise, the two halves of the body would have no communication with one another at all for weak stimuli of sensation and movement, which are extinguished by the resistance of the grey matter; on that account there takes place a partial transference
of nerve-fibres from the one lateral half of the spinal cord to the other. Since a co-operation of the two halves of the body only appears to be requisite with stronger motor stimuli, which besides are conducted through the grey matter, this decussation of the motor fibres extends only to a small fraction, as follows from this, that with unilateral section of the spinal cord only weak disturbances of movement become visible on the uninjured half of the body; with stimuli producing sensation, on the other hand, an exact connection of the two halves of the body is requisite for weak stimuli, and therefore the decussation of the sensory conducting fibres is a far more considerable one (Wundt, pp. 114–115). In the higher central organs, too, this order everywhere recurs, that the connection between the two halves of the body is established partly by bridges of grey matter or by special commissures (i.e., conducting communicating strands), partly by decussation of the paths.
Of special interest is this relation in the chiasma of the optic nerve, which was formerly regarded as the point where the two optic nerves crossed. But that is only true of animals with outwardly-turned eyes, which have no common field of vision for the two eyes; whereas, on the contrary, with man and animals with a binocular field of vision, only the half of the fibres of any nerve, and that too the one turned inward, passes over to the other side, whereas the outer halves remain uncrossed. The consequence of this is, that the left halves of both retinas are combined in the left, the right halves of both retinas in the right corpus quadrigeminum. In animals with outwardly turned eyes injury of a corpus quadrigeminum causes blindness of the opposite eye, but in man disease of one corpus quadrigeminum, hemiopia, i.e., blindness or destruction of vision in the left or right half of the two retinas (Wundt, p. 146). It is obvious that only by this blending of the similarly situated halves of the two peripheral organs in one-half of the central organ is the blending of corresponding impressions on the two retinas explained, i.e., the riddle is solved of single vision, with two, eyes, and I have specially discussed this example because we have according to its analogy to imagine the whole arrangement of our nervous system, which, in spite of the two-sidedness, both of the central and also of the peripheral organs of sensation, yet leads to an indivisible sensation of our body even for the weakest stimuli. Only the union by central bridges or commissures with partial peripheral decussations of the paths makes this result possible, and helps us out of a condition in which we should feel the two halves of our body as if they were two separate bodies; and it only remains to the thinking consciousness to grasp these separate sensations into a unity, just as the owner of an estate can manage two properties entirely separated from each other with the help of a single ledger. It is true the necessity of the union by commissures with partial decussation of the paths holds good only for the spinal cord and the hinder and middle parts of the brain, but not for the fore-brain or cerebrum, and that for the twofold reason that in the first place the union of the cerebral hemispheres by commissures and arcuate fibres into a single indivisibly functioning organ is a far more intimate one than in the afore-named centres; and, secondly, because the motor-impulses of the cerebrum must always first pass through media (at any rate through the motor ganglia of the peduncle of the cerebrum), in which the blending in question is already performed by partial crossing of the paths, so that a repetition of these means would be superfluous. The cerebral hemispheres are therefore in man the only organ in which the decussation of the afferent unilateral paths is not a partial but a total one.
That the spinal cord in its grey matter is a central organ of lower order with a certain relative independence may now be considered as pretty generally acknowledged. Maudsley says: “There can be no difficulty in admitting that the spinal cord is an independent centre of so-called aim-working acts that are not attended with consciousness” (i.e., brain-consciousness). “It is the centre, however, not only of co-ordinate action the capability of which has been implanted in its original constitution, but also of co-ordinate action the power of which has been gradually acquired and matured through individual experience. Like the brain, the spinal cord has, so to speak, its memory, and must be educated” (p. 149). “In fact, if any one attends to his ordinary actions during the day, it will be surprising how small a proportion of them are consciously willed, how large a proportion, of them are the results of the acquired automatic action of the organism” (p. 152). “Of these unconscious or involuntary actions a great part is plainly due to the independent power of reaction which the ganglionic cells of the spinal cord have” (p. 136). “The anencephalic infant, in which absence of brain involves an absence of consciousness, not only exhibits movements of its limbs, but is capable also of the associated reflex acts of sucking and crying” (p. 137). “Pflüger1 touched with acetic acid the thigh of a decapitated frog over its internal condyle; it wiped it off with the dorsal surface of the foot of the same side; he thereupon cut off the foot, and applied the acid to the same spot; the animal attempted to wipe it off again with the foot of that side, but, having lost its foot, of course could not. After some fruitless efforts, therefore, it ceased to try in that way, seemed unquiet, ‘as though it were searching for some new means,’ and at last it made use of the foot of the other leg, and succeeded in wiping off the acid. … Notably we have in this striking experiment not merely contraction of muscles, but combined movements in due sequence for a special purpose; we have actions that have all the appearance of being instigated by will and guided by intelligence in an animal the recognised organ of whose intelligence and will has been removed. So much was Pflüger impressed by this wonderful adaptation of means to an end in a headless animal, that he actually inferred that the spinal cord, like the brain, was possessed of sensorial functions. Others, who would scarce admit Pflüger’s supposition to be true of man, have thought that it might be so of some of the lower animals. Instead of grounding their judgment of the complex phenomena in man on their experience of the simpler instances exhibited by the lower animals, they have applied to the lower animals what I believe to be their subjective misinterpretation of the complex phenomena in man” (p. 138).
Maudsley here announces an important methodological principle for comparative physiology and psychology, which I have also followed above in Sect. A. Chap. i., and for the observance of which I have often been reproached by scientific specialists. Nevertheless, this principle ought to be self-evident to every naturalist, and it is only the psychological prejudice: that no consciousness can inhabit my organism of which my consciousness, i.e., the consciousness of my cerebral hemispheres, is not aware,—which has closed even to a Wundt the comprehension of the fundamental fact of physiological psychology, namely, the capacity of every ganglionic cell to be conscious.
4. The Inner Psychical Aspect of the Reflex Process .—The conception of reflexion may be taken in a narrower and a wider sense. In the former case it signifies the immediate passing over of a stimulus of sensation to the motor nerve issuing in the same centre; in the latter case it signifies any reaction of a centre on a stimulus conducted from any quarter whatever. We have already seen that even the apparently simple reflexion of a centre of the spinal cord is a complicated phenomenon, which is compounded of single actions of several ganglion-cells of the posterior and anterior cornua, each of which is only to be subsumed under the notion reflexion in the wider sense. In the same way also, however, the apparently immediate reflexion passes gradually into ever more complicated forms, as I have already shown above in Sect. A. Chap. v., so that the collective mental functions of man fall under the notion of reflexion in the wider sense. For the latter says nothing more than that no ganglionic cell performs its office without a stimulus, but it says nothing about the kind of stimulus or the kind of function. As the stimulus acting on a sensory nerve may arise from a mechanical, chemical, thermal, or electrical source, so can the stimulus of a sensory nerve-fibre soliciting a ganglionic cell to be functional arise from a neighbouring ganglioncell, from a fibre communicating between a co-ordinate, superordinat
e, or subordinate centre, or perhaps from a motor nerve-fibre;1 and the reaction need by no means be immediately an innervation of a motor nerve, but may consist of a propagation of the actively modified stimulus to neighbouring cells or to conducting fibres which lead to co-ordinate, superordinate, or subordinate centres. Every function of a brain-cell which appears subjectively as abstract idea would then be a reflex due to a stimulus received from another cell or from a sensory nerve, which would be subjectively presented as excitement of the conception through association of ideas or through senseperception.
If, on the other hand, one characterises as “reflex” only the whole group of individual reactions which lie between the irritation of sensory nerves as first term and the function of motor nerves as final term, one does not thereby avoid the fact that the highest functions of the mind come under the notion of Reflexion. For if the stimulus at all lies above the threshold of reflexion, i.e., if it is not absorbed and extinguished on its way in the central organs through the resistance in conduction, it must also, under all circumstances, finally lead to motor reaction, however long it may in the mean time wander about within the central organs from one ganglion-cell to another, or, to speak psychologically, however many reflections and conflicts of desire may be intercalated between perception and voluntary resolution. In this way of looking at the matter likewise the question then is only concerning a difference of degree in the number of connecting links between stimulus of sensation and movement of reaction; and this number gradually rises from the simplest reflex contractions to the most complicated processes needed for the control and management of the external world.
Philosophy of the Unconscious Page 101