But SWEDENBORG, as is well known, did not stop here. The cerebral cortex
certainly constituted a whole which transformed the sensations into
thoughts and determinations, but all the regions of the cortex were not
of the same degree: some ruled the higher, others the lower functions,
thus also containing subdivisions, in some of which the sense-impressions
were received, in others from which the motor impulses proceeded. (See
›The Brain›, Nos. 66, 68, 71, 88, 98, 100, 102, etc.).
This conception of the brain appears at first glance as very modern.
But upon searching the literature before SWEDENBORG’s time one finds
that the thought was not so entirely original. New was the thought of
attributing the psychical functions to the cortex, new also was the
attempt to accurately determine upon the place where the different
functions originate; but the _idea of localization_ itself is found again
in the literature which SWEDENBORG already had at his disposal.
BOERHAAVE, for instance, says, in his ›Institutiones medicæ›, when
speaking of the sensations, that they give rise to _different
perceptions_, partly owing to the differing species and nature of the
outer objects, and partly to the different natures of the sense-organ
and the affected nerve, but partly also _to the different regions in the
cerebral medulla from which the nerve proceeds_. Thus we have here a
kind of localization to a special region of the brain, although in its
_medulla_.[71] And still more clearly does BOERHAAVE express the same
idea in his ›Prælectiones academicae,› where he says: ›In the ’Sensorium
commune’ there are _regions locally distinguished for the different
senses, just as every sense has its own special sense-organ_.›[72]
And before BOERHAAVE the philosopher DESCARTES had expressed an idea
concerning a certain form of localization of the various elements of
psychic activity. For he supposed that the images of sensation and the
images of the memory, etc., which the soul perceives, arise on those
places on the walls of the brain’s central ventricle, where, according
to his opinion, the various nerves originate. In a similar way he also
imagined the origin of motility localized. (R. DESCARTES: ›De homine›,
publ. by F. SCHUYL, Ludg. Bat., 1662).
We here reproduce some illustrations from the work of DESCARTES just
mentioned, which are designed to show how he thought that the images of
sensation arise. — — See the figures 1, 2, 3.
We thus see that the idea of localization itself was not altogether new.
But how did SWEDENBORG ultimate and develope it?
With regard to function SWEDENBORG divided the hemispheres of the
cerebrum into two parts: one anterior region and one posterior,
conceiving the fissure of Sylvius as the dividing boundary between them.
(›The Brain›, Nos. 16, 88, 91).
[Illustration: Fig. 1. Fig. 2. Fig. 3. Fig. 4.
Figures 1-3. Reproduced from Descartes: ›Tractatus de homine›.
Fig. 1. A part of the wall of the central ventricle of the brain. The
points of the dotted area represent the openings of the nerves, which,
according to the opinion of Descartes, take their origin in the wall
of the ventricle. The figures O (star) and B (lily) are formed by
combinations of such nerve openings.
Fig. 2. View of the left hemisphere from the medial side. The dotted
area B represents the place, where, according to Descartes, the nerves
originate. The vesicle H is the pineal gland, wherein the soul was
thought to have its seat.
Fig. 3. Illustrates the act of seeing. The object ABCD forms an image,
1357, on the retina of the eye. This image provokes a similar image,
2468, on the wall of the brain’s ventricle, by exciting a stream of
›spiritus animalis› from the central ventricle through certain of the
fine nerve tubules of the optic nerve, the openings of the nerve tubules
in the wall of the ventricle being widened and thus forming images (of
sight), which the soul is able to perceive from its seat in the pineal
gland.
Fig. 4. Reproduced from Vieussens: ›Neurographia universalis›, Tabula
XVI. Illustrates the passage of the coarse fibres of the _middle region
of the brain’s medullary substance_ through the capsula interna, pons
and the pyramids on the front of the medulla oblongata downwards to _the
anterior part of the spinal cord_.]
To the anterior region he attributed the actual operation of the soul,
while he supposed that the posterior region was chiefly engaged in the
animation of the blood. He adds, however, ›it cannot be denied that
sensations reach even the posterior region of the brain, yet our mind
does not become conscious of them to the same degree as it does in the
anterior region› (›The Brain›, No. 71).
In this _anterior region of the cerebrum_ he distinguished _three
lobes_, or so called ›curiae›, the first one highest up, ›in the crown›,
a middle one below it, and a third one lowest down, _i. e._, nearest
to the fissure of Sylvius.[73] In these three lobes the actual psychic
life is developed, and that so much the more clearly and perfectly, the
higher up in the region these intricate processes occur. It is here that
perceptions, thoughts, judgments, conclusions, come into being; it is
from here that ultimately will and determination issue. (See ›The Brain›,
Nos. 12, 66, 71, 88, 98, 100, 102).
As regards the sensory part of the psychic activity, SWEDENBORG does not
make any attempt at a detailed localization; but as regards the motor
functions he arranges their centres within the above-mentioned regions as
follows: ›_The muscles and actions_ which are _in the ultimates of the
body_ or in the soles of the feet seem to depend more immediately _upon
the highest parts_ (_of the brain_), upon _the middle lobe_ the muscles
which belong to _the abdomen and thorax_, and upon the _third lobe_ those
which belong to _the face and head_;› and he adds, ›for they seem to
correspond to one another in an inverse ratio› (›The Brain›, No. 68).
Whence did SWEDENBORG get all this? Whence the whole of this doctrine
of localizations? In his first great anatomical work, ›Œconomia Regni
Animalis›, nothing is said about it; first in his last anatomical work,
›De Cerebro›, is it advanced, and then — — — quite finished! One is at
first glance tempted to think that he had succeeded in finding some new
clinical experiences, upon which he could found this doctrine. For he had
not even finished the account of the function of the brain’s anterior
region, before interjecting: ›Therefore, if this portion (the anterior
region) of the cerebrum is wounded, then the internal senses—imagination,
memory, thought—suffer; the very will is weakened, and the power of its
determination blunted. This is not the case if the injury is in the back
part of the cerebrum› (›The Brain›, No. 88). But afterwards he does not
bring forward (in ›De Cerebro›) any observations which could serve as
proof with regard to this. And if one examines the cases he has referred
to in his preceding works, one cannot possibly arrive at the localization
of the psychic functions which he has here (in ›De Cerebro›) sketched;
for the evidence concerning the _position_ of the injuries in the cortex
are entirely too scanty and incomplete. But if we consult the _original
descriptions_, we find there many other and more particular data than
those quoted by SWEDENBORG when he was only concerned in explaining the
function of the cortex as a whole. WEPFER, for instance, reports in his
›Historiæ apoplecticorum› concerning the woman seventy years of age, who
suddenly _lost the power of speech_, that the cavity, filled with blood,
which was found in the cortex at the autopsy, was located in the right
hemisphere, _just behind the forehead_ (›ad frontem fere antrorsum›), and
that it extended rather far both backwards and upwards; even measurements
were given (length 8, breadth 4, depth about 2 uncias). It was also
stated that the blood-vessels whose bursting caused bleeding belonged
to the antero-lateral branches of the carotid artery in the brain. It
is also mentioned that no changes were found in the left hemisphere of
the brain; and from the clinical account it appears that even after the
stroke the woman was able to move the extremities of the right side.[74]
— — — All this indicates quite evidently that the lesion of the cortex
was situated in the anterior region of the brain!
And PACCHIONI reports concerning the youth, who was afflicted with the
right-sided _facial paralysis_, that even the extremities of the right
side were somewhat paralysed, and that the cyst, which at the post
mortem examination was found on the left hemisphere, extended _from the
crown to the region of the temple_ (›a capitis vertice in temporalem
regionem›).[75] Thus this case also furnishes an unmistakable indication
that the cortical lesion was situated in the anterior region of the brain.
It seems strange that SWEDENBORG did not here supply an account of
these interesting and convincing cases, which he nevertheless, as we
have seen, was well acquainted with. For his habit is to furnish the
chapters of his works with an introduction in which he reports, often in
very detailed form, the statements of the authors upon which he bases
his conclusions. Since in the present case such an account is lacking,
this may depend: either upon the fact that this last anatomical work of
SWEDENBORG, ›De Cerebro›, was not quite completed and finally edited for
the press, or thereon that Dr. RUDOLF TAFEL, who edited the translation
which is now accessible in print, excluded it. For Dr. TAFEL says in a
note that the introduction to the chapter in question would be introduced
into Part II., chapters 1 and 2, but—Part II. was never printed! Since,
however, the Royal Swedish Academy of Sciences will publish ›De Cerebro›
in its edition of SWEDENBORG’s Scientific works, this question will no
doubt be cleared up. But this much is quite clear from what has already
been adduced, that the cases of paralysis which SWEDENBORG previously
quoted in a brief form are in the original descriptions reported so
completely and in such detail that one can without the least doubt
localize the cortical lesions reported in those cases in the anterior
(superior) region of the cerebrum.
We now pass to an examination of the _anatomical_ literature to which
SWEDENBORG had access. And, as we shall find, we can here see whence
SWEDENBORG derived _material for his detailed doctrine_ concerning
the function of the brain’s anterior region. This becomes evident on
comparing SWEDENBORG’s mode of thinking of the brain’s psychical activity
with the descriptions of preceding authors in anatomy.
The group of nuclei, ›_corpus striatum_›, in the cerebrum had been an
object of special interest for preceding authors.
The Englishman, THOMAS WILLIS, had for example in his ›Cerebri anatome›
(published in 1667) portrayed them as a kind of junction, ›internodes›,
by which the cerebrum coheres with the medulla oblongata; and he pays
special attention to it on account of its peculiar structure (›The
Brain›, No. 476); and he is said even to have attributed to them the
›Sens commun›.[76]
And the professor in Montpellier, RAIMOND VIEUSSENS, had given in his
›Neurographia universalis› (published in 1685) a very exact description
of the ›corpus striatum›, (not only of its ›superior nuclei›: ›Corp.
striat. sup. ant.› = Nucleus caudatus and ›Corp. striat. sup. post.› =
›Thalamus opticus›, but also of its lower lateral nucleus = ›Nucleus
lentiformis›) as also of the mighty medullary tract of nerve fibres,
i. e., ›capsula interna›, which passes through the same, and which on
the one hand is distributed to the brain, especially to its anterior
(superior) region, and on the other hand by means of the nerves radiates
into the various parts of the body.
(In order to facilitate orientation we may refer to C. TOLDT:
›Anatomischer Atlas›, 1899, 8 Lieferung, Fig. 92: ›Querschnitt des
verlängerten Markes und der Gehirnstiele. Verlauf der Pyramidenbahn von
der Pyramidenkreuzung an durch die Pyramide, die Brücke und die Basis
des Grosshirnstiels in die innere Kapsel, woselbst sie in den Stiel des
Stabkranzes, Pedunculus coronæ radiatæ, eingeht.›)
SWEDENBORG, who had studied and often quoted both WILLIS and VIEUSSENS,
likewise attributed a very great significance to the corpus striatum.
All the sensory impressions pass through it to the brain, and all the
voluntary impulses to motion pass out by the same path. (›The Brain›, No.
67). ›It is›, says he in his figurative way, ›in a certain sense, the
Mercury of the Olympus; it announces to the soul what is happening to the
body, and it bears the mandates of the soul to the body› (›The Brain›,
No. 67).
And as the corpus striatum lay most immediately under the anterior
(superior) region of the brain, and was in close connection with it, so
the sensory impressions would for the most part pass to this region, and
the voluntary impulses to motion would likewise proceed from it (›The
Brain›, Nos. 66, 67).
The same VIEUSSENS had furnished a very detailed description of the
passage of the nerve tracts in question, which pass through the corpus
striatum and capsula interna, and had followed them both upwards towards
the hemispheres of the brain and downwards towards the spinal cord. When
he followed them upwards, he found that they formed _three regions_
in the ›centrum ovale›: the _regio superna_, highest up nearest the
crown, the _regio media_, in the middle, and the _regio infima_, lowest
down, and consequently nearest the fissure of Sylvius. (R. VIEUSSENS:
›Neurographia univ.›, pp. 115 and 117).
In these regions of the cerebral medulla, especially in the highest,
VIEUSSENS considered that the soul’s activity had its seat: with the help
of ›spiritus animalis› the soul here had an opportunity of receiving the
sensory impressions, and in the fine and finest nerve fibres there were
here formed sensory images, conceptions, (Op. cit. p. 129), here the
memory images were preserved, (Op. cit. p. 135), and here the faculty of
judgment had its seat, (Op. cit. p. 137), etc.
In these regions, especially in the highest, the will also had its seat
and origin, and at its command the ›spiritus animalis› streamed out
through the nerves, thus conveying the impulses to motion to the various
muscles of the body. (Op. cit. pp. 122, 123, 188, _et seqq._).
For SWEDENBORG, who had arrived at certainty with regard to the seat
of the soul’s activity in the cerebral cortex, and not in the cerebral
medulla!, and who through MALPIGHI and others had been led to see that
_the fibres of the cerebral medulla_ were _continuations of the processes
of the cortical elements_,—for SWEDENBORG it naturally lay very near at
hand to _follow the fibres of the three regions of_ VIEUSSENS _out to the
cortical substance_ on the surface of the brain; and so SWEDENBORG has
his _three cortical lobes_! And to them, especially to the highest, he
could now attribute the source of the soul’s life.
When VIEUSSENS followed the nerve tracts of the corpora striata and
capsula interna downwards, he found:
that the _fibres of the uppermost region_ led down to the _posterior
region of the spinal cord_; (›ad posticam spinalis medullæ regionem›);[77]
that the _fibres of the middle region_, which were especially coarse and
traversed the capsula interna and pons, forming thick tracts, could be
clearly followed down into the _anterior portion of the spinal cord, (›in
anticam spinalis medullæ partem›)_, where they came into connection with
the anterior origins of the spinal nerves, (›ad antica nervorum spinalium
principia›), also paying, on their passing through the medulla oblongata,
›necessary tribute›, (›necessarium vectigal›), as it is expressed, to
certain of its nerves;[78]——See the figure 4!——
that the _fibres of the lowest region_ were distributed to certain
_nerves, which proceed from the medulla oblongata_, and to _some of the
anterior origins of the spinal nerves_ (›quædam illius pars ad quosdam e
Medulla oblongata prodeuntes, altera vero ad antica nervorum spinalium
principia›).[79]
In SWEDENBORG’s time it was, however, known that the muscles which
produce the movements of the head and face receive their nerves just
from the medulla oblongata and the uppermost part of the spinal cord;
and it therefore lay near at hand for SWEDENBORG, when he saw that
paralyses arose when certain cortical regions were destroyed, to draw the
conclusion, that the muscles and movements which belong to the _face and
head_, depend more immediately upon the _lowest_ region of the third lobe
of the cerebral cortex.
And as it was also known that the muscles of the thorax and abdomen
receive their nerves from the superior portion of the spinal cord,
whither just the tracts of coarse fibres from the middle region of the
brain could be followed, (see figure 4), so SWEDENBORG could likewise
draw the conclusion from this that the muscles and movements which belong
to the _thorax and abdomen_ depend more immediately upon the _middle_
region or lobe.
It might now appear tempting to continue the conclusion by connecting the
remaining highest lobe and the lower extremity. But probably SWEDENBORG
did not consider that he had sufficient ground for this. The description
by VIEUSSENS did not here furnish any suitable guidance, for it was
possible that the coarse fibres of the middle region continued so far
down into the spinal cord that they could innervate not only the muscles
of the abdomen but also those of the lower extremity. For this reason
SWEDENBORG refrains from localizing exactly the centre of motion of
the lower extremity and contents himself with stating in general terms
only that this centre might lie above that of the abdomen. He therefore
says: ›the order seems to be so disposed that——the muscles and actions,
which are in the _ultimates_ of the body, or in the soles of the feet,
depend more immediately upon _the highest parts (of the brain)_›, whereas
concerning the thorax and abdomen he says that they depend upon the
middle _lobe_, and of the head that it depends upon the third _lobe_.
(›The Brain›, No. 68). I believe that this is the reason why SWEDENBORG’s
doctrine of localizations as concerns the motor centre of the lower
extremity is expressed in such vague terms.
From a comparison of these descriptions by SWEDENBORG and VIEUSSENS we
have found that there are such considerable similarities between them
that they in many respects agree point for point. And it therefore seems
to me rather probable that SWEDENBORG derived his conception of the more
detailed localization of the soul’s activity from the descriptions of
VIEUSSENS.