RECENT INVESTIGATIONS 
INTO THE 
PHISIOLOGICM. RUCTIONS OF THE GRAIN. 
II. K. Bigelow, M. D., Hartford, Conn. 
Some months ago I published in the Canada Medical and Sur- 
gical Journal, an article on the “ Physiology and Psychology of the 
Brain,” in which I endeavored, in a very general way, to reduce the 
modern facts, theoretrical and practical, relative to the Physiological 
and Metaphysical action of the Brain. We shall now be more con- 
cerned in the causation of paralyses, in the examination of the 
relations and functions of the cerebral centrifugal and centripetal 
nerve fibres, which transmit the force or convey the sensation, and 
in the consideration of the inter-relationship of the cerebral circu- 
lation, with the clinical evidences of pathological change. In the 
most essential particulars the views of yesterday are not those of 
to-day, yet the olden theories, not old in point of time, but merely 
as untenable premises are still tenaciously clung to, by many pro- 
fessional men. Professor Meynert* sees in the central nervous sys- 
tem a mechanism for receiving, storing up, and transmitting, 
but not for originating excitations. 
All excitations which affect the nervous system at all reach 
tiually the cortex cerebri, upon which they may be said, in the geo- 
metrical sense, to be projected. The centripetal nerve fibres, 
through which this projection is accomplished, are included, 
together with the centrifugal fibres which place the Brain again in 
communication with the muscles, under the name of the “ Projec- 
tion System,” in contradistinction to those systems of fibres which 
terminate with both their extremities in the cortex cerebri, and 
* Strieker’s Manual of Histology. J. J. Putnam’s Summary, Archives Scientific Med., Feb- 
ruary, 1873. FUNCTIONS OF THE BRAIN.— BIGELOW. 
which serve to establish a functional unity between the different 
parts of that organ. These latter he calls the Association System. 
This article is full of brilliant hypotheses which it would be inter- 
esting to follow, but there is so much to reduce that the limits of 
an article will will hardly permit an extended review, and we pass 
to a consideration of the views which Dr. Brown-Sequardf consid- 
ers well established, or most probable as regards the physiology and 
the physiological pathology of the Brain. 
1. —The brain is a completely double organ, each of the hemis- 
pheres being a whole brain in itself, not only for mental actions as 
ably maintained by Sir Ilenry Holland, and by Dr. A. L. Wigan, 
but also for every other function (volition, intellectual perception 
of sensations, etc.) known to belong to the various parts of the cen- 
tral mass of nervous tissue named Encephalon. 
2. —Originally no marked difference exists between the right and 
left hemispheres, each of them being in newly-born children almost 
as well able by natural development and future exercise to acquire 
all the functional powers of the brain; but as one of the two hem- 
ispheres being sufficient for certain functions, is exercised more 
than the other, it comes to be much more apt than the other to 
execute these functions. This view, ably maintained by Dr. W. 
Moxon, and accepted by Dr. P. Broca, so far as the faculty of speech 
is concerned, is just as well founded for the power of volition on 
the muscles, and for several other functions of the brain. 
3. The communications between muscles and brain as centres 
for volition take place in a normal state by two (if not more) dis- 
tinct sets of conductors, one passing from a lateral half of the brain 
to the muscles of the corresponding side in the trunk and limbs, 
and remaining in all their length in the same side of the cerebro- 
spinal axis, the other set (or sets) decussating with the hom- 
ologous set coming from the other side of the brain, going to the 
muscles of the trunk and limbs on the other side, (opposite.) 
4. —The decussation of the conductors serving to voluntary 
movements takes place not entirely or even chiefly where most 
physiologists and physicians believe it to occur, i. e., in the lower 
and front part of the medulla oblongata; but all along the median 
t Archives of Scientific and Practical Medicine, Feb., 1873. FUNCTIONS OF THE BRAIN.—BIGELOW. 
plane of the cerebro-spinal centre, from the crura-cerebri to the 
lumbar extremity of the spinal cord, including, of course, the pons 
varolii and the medulla oblongata. 
5.—The transmission of sensitive impressions, coming from 
the lateral halves of the body, takes place also by at least two sets 
of conductors, one going up to the brain in a direct way, i. e. re- 
maining in the corresponding half of the spinal cord and of the. 
brain, while the other passes into the other half of these nervous 
centres, decussating all along the spinal cord and medulla oblongata 
with the homologous fibres coming from the opposite side. 
G.—The decussation of these last conductors takes place along 
the median plane of the spinal cord for the trunk and limbs, and 
of the encephalon for the nerves of general and special sensibility 
arising from that part of the nervous centres. 
7. —Very few conductors, direct or decussating are sufficient for 
complete communication between the brain and spinal cord, for 
sensibility and voluntary movements. These communications take 
place not by mere prolongations of the nerve fibres of the motor and 
senitive roots of the spinal nerves, after they have reached the cells 
of the spinal cord, but by a very small number of conductors, going 
from groups of these last cells to groups of brain cells. 
8. —The vaso-motor nerves arise from many parts of the nervous 
centres (including the gangloins of the sympathetic.) The me- 
dulla oblongata is the principal place of their decussation. The 
pons varolii is the chief centre from which they originate, either 
for the viscera or for the trunk and limbs. 
0.—The respiratory movements have their centre in the spinal 
cord, the pons varolii and other parts of the encephalon, as well as 
in the medulla oblongata. Ganglions in the diaphragm participate 
in the production of these movements. 
10.—Symptoms of diseases of the brain are of two distinct classes: 
those which arise from an iniluence exerted on distant parts by an 
irritation of the deceased part (indirect symptoms), and those pro- 
duced in a direct way, either by the loss of function or the irritation 
of the part diseased. The first class will be observed in all cases of 
diseases of the brain which produce symptoms. This first class 
will co-exist with the second in most cases of diseases of the base of FUNCTIONS OF THE BRATN.—BIGELOW. 
the brain; but it exists alone in cases of diseases located in the 
cerebral lobes, the cerebellum or its peduncles. 
11. —The indirect symptoms are of two kinds, both arising, how- 
ever, from an influence exerted on distant parts by an irritation 
starting from the organic lesion that we may see after death. 01 the 
first kind are those symptoms due to a paralyzing influence; and 
of the second kind are those in which, instead of cessation of activ- 
ity, there is on the contrary the manifestation of a morbid activity. 
12. —To the group of indirect (inhibitory or arrestatory) symp- 
toms belong various kinds of cessation of activity, including the 
loss of voluntary movements, anaesthesia, amaurosis, aphasia, loss 
of consciousness, loss of the power of controlling the sphincters, 
etc. 
13. —To the group of indirect production of a morbid activity 
belong delirium, convulsions and other active disorders of muscular 
movements. 
14. —The mechanism of production of the indirect symptoms of 
an organic disease of the brain seems to be identical with that of the 
reflected symptoms due to the irritation of peripheric nerves in the 
bowels, the lungs, the skin, or in any other parts of the trunk and 
limbs. 
15. —In the same way that an irritation of a peripheric nerve 
will sometimes produce no indirect symptom (i. e. a symptom due 
to an influence exerted on distant parts) or will in other instances 
produce any one of the indirect symptoms (those of cessation of 
activity, or those of production of a morbid activity,) in that same 
way will a lesion of the brain, extensive or not, produce no indi- 
rect symptom, or engender any one of the many indirect symptoms. 
16. —The above being admitted, it is easy to understand all the 
differences that may be found as regards symptoms of organic dis- 
eases of the brain. It is easy to understand how a paralysis can 
occur on the side of the brain lesion or on the opposite side ; how 
a paralysis can appear suddenly and be complete although the lesion 
is small, and located in a part which cannot by any one be consid- 
ered as the seat of the will, or containing the conductors for the 
voluntary movements of the parts paralyzed; and how, also, a par- 
alysis can disappear suddenly, although the brain lesion which FUNCTIONS OF THE BRAIN.—BIGELOW. 
5 
gives rise to it still remains. It is easy to understand why there is 
no relation whatever between the extent, the kind, the seat and the 
rapidity of an organic disease of, or an injury to, the brain, and the 
symptoms that may appe ir. It is only in the acceptance of these 
views in their fullest sense, that we can at all hope to master clinical 
diagnosis. Htfghlings Jackson* says: ‘‘Cases of paralysis and con- 
vulsion may be looked upon as the results of experiments made by 
disease on particular parts ot the nervous system of man. The 
study of palsies and convulsions from this point of view is the study 
of the effects of “destroying lesions,” and of the effects of “dis- 
charging lesions,” and for an exact knowledge of the particular 
movements most represented in particular centres, we must ob- 
serve and compare the effects of each kind of lesion. * * * * 
Limited destroying lesions of some parts of the cerebral hemisphere 
produce no obvious symptoms ; whilst discharging lesions of those 
parts produce very striking symptoms. By this double method, we 
shall, I think, not only discover the particular parts of the nervous 
system where certain groups of movements are most represented 
(anatomical localization), but, what is of equal importance, we shall 
also learn the order of action (physiological localization) in which 
those movements are therein represented. I begin by speaking of 
destroying lesions, and take the simplest case—hemiplegia of the 
common form from lesion of the corpus striatum—a blood clot 
which has destroyed part of the corpus striatum has made an ex- 
periment, which reveals to us that movements of the face, tongue, 
arm and leg are represented in that centre. This is the localization 
of the movements anatomically stated. Physiologically we say that 
the patient whose face, tongue, arm and leg are paralyzed, has lost 
the most voluntary movements of one side of his body ; it is equally 
important to keep in mind that he has not lost the more automatic 
movements. The study of hemiplegia shows that from disease of 
the corpus striatum those external parts suffer most which, phys- 
iologically speaking, are most under the command of the will, and 
which, physiologically speaking, have the greater number of different 
movements at the greater number of different intervals. That 
* Lancet, April, May, &C..S73. FUNCTIONS OF THE BRAIN.—BIGELOW'. 
parts suffer more as they serve involuntary is, I believe, the law of 
destroying lesions of the cerebral nervous centres.” 
And again, “But there is proof that fibres pass from the left cor- 
pus striatum down into the left side of the cord, as well as into the 
right side; there are “direct” as well as “decussating” fibres. That 
there is a “decussating paralysis” from lesion of the left corpus 
striatum, no one doubts ; but the existence of direct fibres, I think, 
supports the “inference that there is also a transient “direct paral- 
ysis” from extensive lesion of that centre. After old lesions of the 
left corpus striatum there is Wallerian wasting of nerve 
traceable from the seat of disease, not only down into the right side 
of the cord, but also into the left. This splitting of the bundle of 
wasted fibres on entering the cord is, I think, demonstrative evi- 
dence that both sides of the body are represented in the left corpus 
striatum. Does it not show that movements of the left face, arm 
and leg, are represented in the left corpus striatum by the non- 
crossing fibres, as well as that movements of the right face, arm and 
leg, are therein represented by the crossing fibres ? 
It may, however, bo urged that these non-crossing fibres are solely 
for the bilaterally acting muscles (“ muscles of the trunk.”) But 
if we now consider the phenomena of a severe convulsion and find 
that from a discharging lesion of the left side of the brain the left 
face, arm and leg, are convulsed (after the right side) it is, I think? 
most reasonable to conclude that the non-crossing fibres are for the 
movements of the muscles of the left face, arm, and leg, although 
perhaps chiefly for those of the left side of the trunk.” Ilence we 
may conclude that both sides of the body are represented in each 
side of the brain, through this double arrangement of nerve 
fibre. 
Having looked into this nervous co-relation, imperfectly I con- 
fess, but as thoroughly as a due regard for the economy of space 
and time will permit, I shall pass now to the review of some facts 
relating to the circulation of the brain, and its relation to‘apoplexy, 
syncope, &c. 
The doctrine of the invariable quantity of blood within the cra- 
nium was first asserted by Dr. Alex. Monroe, of Edinburgh. He FUNCTIONS OF TIIE BRAIN.—BIGELOW. 
observes:* “As the substance of the brain, like that of the other 
solids of the body, is nearly incompressible, the quantity of blood 
within the head must be the same at all times, whether in health 
or disease, in life or after death, those cases only excepted in which 
water or other matter is effused or secreted from the blood vessels; 
for in these cases, a quantity of blood, equal in bulk to the effused 
matter, will be pressed out of the cranium.”f 
This view is essentially the same as that which Dr. Abercrombie, 
upon the authority of Dr. Yiellie, long since propagated. These 
experiments of Dr. Viellie, and the inferences drawn for them, con- 
tinued to obtain, until Dr. George Burrows, in his Lumleian Lec- 
tures, 1843-44, exposed the fallacy, and proved that the quantity of 
blood within the cranium, so far irom being a constant or nearly 
constant quantity, is, on the contrary, as variable as in the other 
parts of the body, and the recent researches of Prof. His into the 
perivascular sheaths surrounding the cerebral vessels are corrobo- 
rating proof. The numerous fissures and foramina for the trans- 
mission of nerves and vessels through the bones of the cranium, do 
away with the idea of the cranium being a perfect sphere like a 
glass globe. 
We recognize certain cases of congestion, of anosmia, and we 
know that in sleep the brain becomes anaemic, ’though Dr. Rich” 
ardson has recently advanced the idea of natural sleep being caused 
by some molecular change in the cerebro-spinal system—this, how- 
ever, requires further proof. The inhalation of chloride of amyl 
induces deep sleep and ancemia of the brain. Methylic ether causes 
deep sleep and congestion of the brain. The intra-cranial altera- 
tions give rise to certain intra-ocular appearances, which I shall 
fully describe under the head of the “opthalmoscope.” The amount 
of vascular pressure within the brain is of great influence on the 
functions of the brain. Dr. Burrows! closes his article on this sub- 
ject as follows: 
“On this interesting and important principle of pressure, 1 have 
endeavored to point out that such a force is constantly in operation 
* Observations, Ac., on the Nervous System. Alexander Monroe, M. 1)., 1873. 
t Dr. Abercrombie. Pathological and Practical Researches on Diseases of the Brain and 
Spinal Cord. Am Ed. p. 218. 
t Burrows on Cerebral Circulation. FUNCTIONS OF THE BRAIN.—BIGELOW. 
upon the cerebral substance; that this pressure is produced by vas- 
cular distension; that in health, any cause which is capable of in- 
creasing or diminishing this vascular distension has the effect of 
disturbing the functions of the brain; that these effects of vascular 
distension would be more serious and frequent if parts of the con- 
tents of the cranium were not readily removable upon increase of 
vascular pressure ; that in pre-existing structural diseases of the en- 
cephalon, any increase of vascular distension causes much more 
serious disturbance of the cerebral functions, and the symptoms so 
produced are analgous to those of mechanical pressure on the brain. 
I have also attempted to support the opinion that variations of this 
vascular pressure are the causes of the intermitting character of the 
more urgent symptoms in cases of permanent disease within the 
cranium. 
I have likewise endeavored to explain the phenomena of syncope, 
however produced, on the principle of diminished momentum of 
blood in the arteries of the head, and consequent diminished vas- 
cular pressure on the cerebral substance, rather than on the prin- 
ciple that the brain is not supplied with a sufficient quantity of 
blood. 
And, lastly, I nave accounted for many of the symptoms of dis- 
turbance of the brain in general ansemea, upon the hypothesis of 
an insufficient vascular pressure on the substance of that organ.” 
The same author says : “There are probably several causes capa- 
ble of suspending the functions of the brain, and producing coma, 
and these causes are analogous to those which we experimentally 
find are adequate to destroy the functions of the cerebro-spinal 
nerves in any part of their course. These causes may be enumera- 
ted in the following order : First, pressure on the nervous fibres ; 
secondly, division of the nervous substance; thirdly, disorganiza- 
tion of the nervous matter; fourthly, interrupted supply, or de- 
ficient momentum of blood in the nervous substance; and fifthly, 
the action of narcotics. 
It appears to me that the true explanation of the cause of the 
coma in these cases of so-called simple apoplexy, is to be found in 
the previous existence of a state of congestion of the vessels within 
the cranium, brought on either by determination of blood to the FUNCTIONS OF '1II E BRAIN.—BIGELOW. 
head or detention of Idood in that part. Then, as Dr. Watson has 
well expressed it, a tightening of the full vessels occasions extraor- 
dinary pressure on the nervous pulp; and hence the coma. But if 
this be the correct explanation of the production of the coma in the 
simple apoplexy of Abercrombie, why does the coma persist, and 
death so speedily ensue, although the vascular distension, the sup- 
posed cause of pressure, is removed by abstraction of blood, or other 
remedies, and, as we ascertain after death, the brain has sustained 
no structural lesion? 
This is a question worthy of consideration. The fatal event is 
probably to be ascribed to another cause. If, in these attacks, the 
pressure on the brain has been adequate to suspend consciousness 
for a time, and the respiration has become altogether involuntary, 
slow, and stertorous, the substance of the brain is gradually satu- 
rated with undecarbonized blood. The apoplectic person remains 
in a condition analogous to that of one whose rimaglottidis is con- 
stricted, or who has been suffering from aprcea for some time. The 
apoplectic person then dit-s, not simply from pressure or lesion of 
the brain, but from the effects of imperfect respiration.” 
If, then, the opthalmoscope reveal to ns anaemia of the disk, we 
may be sure that there is a similar condition, a causative one, ex- 
isting in the brain, and we must treat accordingly. So, also, if 
there be congestion, we should give strychnia or such drugs as will 
diminish this under determination.* 
So also in simple aortic insufficiency, with or without hyper- 
trophy of the left ventricle, there is spontaneous pulsation of the 
arteries of the disk and retina. 
“ The connecting nervous threads which run from the peripheral 
expansions of gray matter, constituting the sensory endowments of 
the skin, to the primary nuclei in the spinal cord, must in some 
manner be connected with the cortical layer in the cerebral lobes, 
otherwise it would be impossible for us to become conscious of the 
sensations which it is their function to convey. It is probable that 
this connection is made by secondary fibres, running from the spi- 
nal nuclei to the sensory-motor ganglia at the base of the brain, and 
that from these latter other fibres are developed which place the 
* Otto Becker : Loudon Ophth. IIos. Rep , Feb.. 1873. FUNCTIONS OF TIIE BRAIN.—BIGELOW. 
investing gray matter of the cerebral hemisphere in immediate com- 
munication with the corpora striata and optic thalami. The fact 
that the primary fibre from the integument to the cord terminates 
in the gray matter of the latter, and that in the other steps of the 
series communication is established through the connection of these 
nerve centres, does not invalidate the statement that there is a di- 
rect connection between the periphery and the supreme centres, al- 
though it renders it doubtful if this communication is made by 
one uninterrupted nerve thread. 
The statement in regard to the connection between the super- 
ficial gray matter of the cerebrum and the peripheral expansions 
of nervous tissue which endow the integument with common sen- 
sibility to pain, is equally true in relation to the cerebral lobes and 
the motor nerves of muscles. An uninterrupted communication 
between the supreme centres and the contractile organs is necessary 
for the conscious performance of voluntary muscular acts. Yet this 
communication may be, and doubtless is, affected by the interven- 
tion of a number of secondary centres and fibres.” f 
This will explain the principle upon which the aesthesiometer is 
made use of in the Physical Diagnosis of Brain Disease; its con- 
struction and service will be dwelt upon at length in another paper. 
To sum up then, in brief, some of the facts which, as skillful di- 
agnosticians, we must be familiar with at the bedside, it is to be 
borne in mind. 
1st. That grave cerebral lesions may exist without characteristic 
semeiology. 
2d. That slight lesions may occasion a train of symptoms indic- 
ative of serious organic disease. 
3d. That a paralysis is caused by the irritation transmitted by 
the cerebral lesion, inhibiting certain functional actions, and not 
by the mere circumscribed pressure. 
4th. That a lesion in the middle line—i. e. affecting both sides 
of the optic tlialmi, striate bodies, &c., may produce paralysis of but 
one side of the body. 
5th. That a paralysis may exist on the same side with the lesion. 
t Yance—Physical Diagnosis of Brain Disease. New York “Medical World,” July, 1871. FUNCTIONS OF THE BIIAIN.—BIGELOW. 
Gth. That unilateral convulsions are much oftener associated 
with lesion of the right brain than with the left. 
7th. That hysterical paralysis &c., depends oftenest upon dis- 
organized action of the right brain. 
8th. That aphasia, agraphia, a mechanical impairment of speech 
and mental alienation, are usually associated with disease of the 
left brain. 
9th. That the right brain is more capable than the left of pro- 
ducing a paralysis on the same or on the opposite side of the body. 
10th. Optic neuritis is a cause of amaurosis depends more often 
on a disease of the right brain than on disease of the left. 
11 tli. The symptoms may indicate a double lesion when one is 
present and conversely.