THE JOURNAL

OF

PSYCHOLOGICAL MEDICINE

AND

MENTAL PATHOLOGY.

JULY 1, 1855.

ART. I.-THE BRAIN IN RELATION TO THE MIND.

It is obvious that physiological psychology cannot be expected to attain that scientific definitiveness characteristic of the more physical departments of philosophical investigation. The relations between the mind and the brain can probably be never determined with scientific precision, the obstacles to such a result being very conceivable. Whilst our researches into purely physical conditions educe facts and circumstances that strike observers with a certain exactness and uniformity, the phenomena of mind—of consciousness—are very often but imperfectly apprehended; and even when these latter are sufficiently distinct and clear to admit of notation and record, their significance, in the estimation of inquirers, is by no means uniform. Thus, whilst science in general, including the inferior branches of physiology, has of late years progressed with giant strides, a physiology of brain and mind that commands universal acquiescence has not nearly been attained. In order to realize a system of analytical psychology that should stand in obvious relation with a doctrine of the cerebral functions, we ought to be able to note the varying phases of consciousness in their outward manifestations with some such readiness and facility as that with which we estimate physical conditions. Were this within our power, we might go far to the accomplishment of a truly scientific psychology, based upon our knowledge of the structure and offices of the brain. The inevitable want of an objective standard to measure the value of mental facts, causes them to be devoid of satisfactory comparability: hence, psychical phenomena admit of no perfect system of classification; and, with still less exactitude, can they be compared with physical facts and conditions. Yet scientific induction demands complete and obvious recognition of the comparable worth

of all the circumstances that constitute the premises. Again, most of the materials obtainable for establishing conclusions regarding mental phenomena, are made up of certain outward manifestations that do not always suggest a very clear or unmistakeable interpretation. We note the external facts of consciousness in the several grades of animal life, from the lowest creatures up to man; but, in determining their significance, we have to speculate and to reason mainly from the analogies gained by introspection of ourselves. Moreover, in tracing the sequence of phenomena that characterize cerebro-mental action, we have ever to pause upon attaining the last change in molecular disposition that causally precedes inchoate consciousness. Between the line that bounds the ultimate physical condition and that which borders the primary psychical state, there is an inestimable chasm. The connecting link, indeed, between matter and mind must always remain, as it is, inscrutable to scientific investigation.

And yet these abstract difficulties, inherent in the subject, have not prevented inquisitive minds in all ages from hazarding speculations concerning the relations of psychical phenomena to the physical organization. In later times, indeed, conclusions have been attained with regard to this matter, that carry with them almost every stamp of authenticity short of actual demonstration. In a very early stage of physiological inquiry, it was considered that the brain and nerves had some special connexion with the manifestations of conscious life; and, in modern times, this, as a general proposition, takes rank as scientific truth. The special functions of the spinal cord and of particular nerves were partly anticipated, long before doctrines upon the subject were sustained by demonstration. The idea that the separate ganglia of the sympathetic nervous system were independent sources of power, suggested itself to Dr. Johnson, of Birmingham, about the middle of the last century, prior to Bichat's advancement of a similar hypothesis. And, as is well known, the researches of Gall, early in the present century, brought prominently before physiologists a theory, in principle now generally admitted, to the effect that the encephalon is not a simple organ, but that particular portions subserve different mental functions-a principle the correctness of which is hardly to be doubted, whatever be the errors and exaggerations of phrenologists. But, however just may have been many of the anticipations that prevailed in the early part of the present century, or at epochs anterior to it, very few of the general notions upon the brain and nervous system could be maintained as scientific induction. It is almost altogether of late years that patient and persevering observation, and ingenious experiments, have been systematically applied to obtain results that partake very largely of philosophical accuracy, even when

they do not entirely fulfil its imperious requirements. The researches of Bell, Magendie, and Bellingeri, demonstrated the anatomical distinctness of the motor and sentient nerves. Marshall Hall showed by experiment and pathological facts, that the spinal cord is a source of nervous power, independent of the brain, and urged, by convincing reasons, that its influence in the production of muscular movement was exercised without any necessarily attendant consciousness. Numerous facts and observations, particularly the experiments of Axmann, of Berlin, have rendered it probable in the highest degree, that the sympathetic nervous system presides over motions involved in the processes of circulation, nutrition, and secretion. With respect to these inquiries concerning the functions of the nervous system, our knowledge has become considerable, and in many respects exact. Even in those cases wherein the results cannot be absolutely maintained as positive, very promising researches are continually going on, so that our expectations of the future of neurology are of the brightest. But when we come to the encephalon to those masses of nervous substance surmounting the spinal cord, and enclosed within the cranium-our deficiencies and shortcomings become more apparent. Certain general propositions can be maintained; but, when we would advance to particulars, rational hypothesis must be made to supply the defects of theory, if we are disposed to systematize our opinions and views. We can show by numerous facts and solid argument that some of the structures forming the base of the encephalon constitute seats of sensation and sources of motion, but by rigorous processes of induction we can prove little more. When the higher phenomena of consciousness are considered, and when we would establish a connexion of these with the physiological action of parts within the head, the nature of our evidence exhibits a comparative weakness. Certain doctrines now current upon this subject are most probably true, but the testimony sustaining them is of a somewhat different character to that by which the functions of the spinal cord and particular nerves have been made out. Our evidence is less direct; it is circumstantial; and it carries conviction, rather by its cumulative force, than by any immediate demonstration. We appeal to the results of mutilation, to pathological facts, and to comparative anatomy; we note the phenomena of embryonic development, and observe the variation in cranial forms as indicative to some extent of cerebral magnitude and configuration; and, from these several sources of investigation, we arrive at conclusions concerning the physiology of the brain that, in many respects, are but little short of scientific certainty. But when we pass from the general operations of mind and come to such as are special, and attempt to arrange the phenomena in categories,-when we would

make out a distinct relation between particular mental faculties and portions of the cerebral structure,-when, in a few words, we attempt the establishment of some complete physiological psychology, it is then that we discover the insecurity of our footing; an insecurity, most likely, that will never be altogether obviated, on account of the inherent difficulties of the subject.

Up to a certain point, however, undoubted advances have been made in this direction. Some views of the correlation of psychology and physiology can be shown, having higher pretensions than mere hypothesis and verbal subtlety. In regarding the physiology of the brain and nervous system in its totality, we may probably analyse and sum up our actual knowledge, and the most generally received opinions, very briefly as follows:-The notion propounded during the last century, that the sympathetic ganglia constituted independent sources of nervous power, has led, by gradually ascending generalisation, to the conviction, now all but universal, that the grey tissue of all the nervous masses- -the vesicular neurine is identical in its general character with the structures long denominated ganglia, not only in the fact of its being of vesicular composition, but also in that of its being the primary seat of functional change, the influence of which is conducted from part to part by the white fibrous substance; the nerve-trunks thus constituting internuncial cords simply. All the sources of our knowledge contribute more or less to the corroboration of this view. Hence the term ganglion is at this time applied, not only to those smaller spheroidal masses always recognised as ganglia, but also to those larger accumulations of vesicular neurine within the cranium, and to those tracts of the same substance pervading the interior of the medulla spinalis. The sympathetic system itself is probably the most simple in its functions, as it, or its presumed analogue, is the most universally found in the various forms of animal organization; its office being apparently to participate, as before observed, in the maintenance of organic life. In this view, consciousness can have no necessary place in its exercise. The vesicular neurine which is continuous throughout the length of the spinal cord and constitutes the analogue of the ventral ganglia of the articulata, is virtually demonstrated to be for the conservation of the animal fabric, by its subservience to respiration, by governance of the orifices of egress and ingress, and by its contribution to the integrity of some other processes, the purposes of which are mainly conservative. Its function is called into exercise by excitation of the peripheral terminations of nerves that communicate with it, or by influences that operate more immediately. No development of consciousness attends the proper action of the ganglionic masses within the spinal column. The first indications of conscious life show them

selves coincidently with the nerves and ganglia of the external sensesof smell, taste, hearing, sight, and touch; these senses are obviously associated with collections of vesicular neurine which are situated above the spinal cord, and which, in the higher classes of animals, are pro tected by the bones of the skull. The sensory ganglia are, by white nerve-fibres, in direct communication with vesicular neurine expanded on the surfaces forming the special regions of the particular kinds of sensibility. Upon these latter the fitting impressions are made, and upon the extension of their influence to the encephalic centres, consciousness of subjective change-sensation becomes awakened. But at this very point-that at which the correlation of psychology and physiology begins--the demonstrability of prevalent doctrines becomes less complete. Uncertainty to some extent exists thus upon the very threshold. We have even no sure knowledge as to which are the ganglionic centres of touch-the most simple and universal of all sensibilities. Although concerning the ganglia of smell, sight, and hearing we have some reasonable assurance, there is not that fulness of evidence which obtains in many other departments of physiology. The encephalic centre of taste is altogether undetermined. Sensations, in the first instance, determine simple perceptions; and these, as ideas, constitute the elements of thought and fancy. These more complex and varied phases of consciousness are accomplished, it is now very generally believed, through the instrumentality of the vesicular neurine investing the cerebral hemispheres, and hence denominated the hemispherical ganglia. This opinion, though essentially hypothetical, rests upon many substantial grounds, as it accords with the best established facts, alike of general physiology, comparative anatomy, and pathology. Emotional sensibility, and the instinctive appetites, are supposed to have an encephalic locality somewhere among the ganglionic masses situated below the cerebrum proper. And it is commonly thought that harmony in the action of muscles when movement, the result of mental activity, ensues, is secured by the physiological agency of the cerebellum.

This recapitulation of current doctrines of physiology in relation to psychology, comprises views that future investigations may very considerably modify, or altogether set aside. However well supported many of them may appear to be by facts from all sources, they rest upon inadequate foundations, if we would deal with them as with indisputable propositions. By continued researches, they may be made most probably to look much more like truth than even they do at present. It seems to us, however, that with respect to the higher departments of psycho-physiology, complete scientific accuracy is, in the nature of things, not to be anticipated.