The Columbia herald. [volume] (Columbia, Tenn.) 1850-1873, 1873-01-10
Brain Circulation During Sleep.

Lie oAlSU1I1S DcGW0ou bIlc
phenomena of circulation in the brain
and the functional activity of that organ
have long remained obscure, owing to
mistaken ideas of the conditions of sleep
which is rightly considerered the state
of rest of the cerebral organ. The an
clients supposed that sleep resulted from
compression exerted on the brain by the
blood when it's circulation declined.
They imagined that this pressure was
chiefly at the back part of the head, at
the point where the veined folds of the
duramater unite in a common cement,
which is still called the torcular or
compress of Herophilus, from the name
of the anatomist who first described it.
Those conjectural explanations have
been handed down to us; and it is only
of late years that experiment has sue
ceeded in proving their falsity. In fact,
it has been shown by direct experiment
that, during sleep, the brain, instead of
being congested, is, on the contrary,
pale and bloodless; while in state of
wakefulness, it provokes flow of blood
proportional to the intensity of celebral
activity. In this respect natural sleep
and the anesthetic sleep of chloroform
are alike: in both cases the brain, sunk
into rest or inactivity, presents the
same paleness and relative blOodless-
ness.
The experiment is in this manner: A
part of the bony covering of an animals
skull is carefully removed. and the brain
laid bare so as to study the circulation
at the surface of this organ. The chlor-
oform is administered to produce insen-
sibility. In the first exciting stage of
the action of the chloroform, the brain
is observed to grow congested and to
lay over at the edges; but as soon as
the state of an@thetic sleep reached,
the substance of the brain sinks in and
grows pale, presenting languid move
ment of capillary circulation, which lasts
as long as the state of sleep or cerebral
rest continues. For the study of the
brain in natural sleep circular trepan
is made On q dogs head, and the piece
Of bone removed is replaced by watch
glass carefully adjusted to the exact
opening, SO as to prevent the irritating
action of the air. The animals subject
ed to the operation survive it; and OBJ
servations on their brain through this
sort of window, while awake and when
asleep, to prove that when the dog is
asleep the brain is always paler, and
that fresh affiux of blood is regularly
noticed on his awakening, when the
functions of the brain resume their ac-
tivity. Facts analogous to those OBJ
served in animals have been studied di-
rectly in the human brain. Upon per-
son injured by frightful railroad acct
dent the effect of considerable loss of
brain-substance was examined. The
brain was visible over surface of three
by six inches. The patient suffered fire.
quent and severe attacks of epilepsy
and coma during which the brain inva-
riably expanded. Sleep succeeded
these attacks, and the cerebral hernia
gradually subsidized. When the patient
awake the brain again projected and
rose to the level of the surface of the
external bony table. In the case of
another person injured in consequence Of
fracture of the skull, the cerebral was
stuffed during the administration of
anesthetics. With the first inhalations,
the surface of the brain became branchy
and filled with blood; the flow of blood
and throbbing of the brain increased,
and then, at the instant of sleep, its
surface subsidized by degrees below the
opening, while at the sametime growing
relatively pale and bloodless.
Briefly, then, the brain is governed
by the common law that controls blood
circulation in all the organs. By virtue
of this law, when the organs are at rest
and their action suspended, the circula-
ton in them grows languid; and it in
creases, on the contrary, as soon as ac-
tivity is resumed. The brain, repeat,
is no exception to this general law as
had been supposed, for it is now dem
onstrated that the state of sleep coin
cides not with congestion, but, on the
contrary, with bloodlessness of the
brain