Nashville union and American. [volume] (Nashville, Tenn.) 1868-1875, 1874-05-10
HAVE WE TWO BRAINS.

DR.. Brown-Sequard, the eminent
Psychologist, delivered lecture recent
" in Washington on the structure and
functions of the brain. He laid down
the proposition that we have two dis
tinct brains, consisting of the right
side and the left side. In support of
this view he cited many curious facts,
some of which we Will notice as lending
plausibility to his remarkable theory.
PHYSICIANS are well aware that a lesion
in the left side of the brain viii pro-
duce loss of speech, and lesion in the
right viii not. This fact is itself a
proof that the left side is quite distinct
from the right side, that it is In fact a
brain in itself as regards the faculty of
speech. Again, disease existing IN
that part where the optic nerve goes
into the brain, destroying that part
altogether, may not be a cause of loss
of sight; so that one optic track alone
may be perfectly sufficient for the func-
lions of the two eyes. 1t is therefore
concluded that one brain is quite
enough for our power of sight; and, as
it is so for each half of the brain, it Is
thought that each half is independent
of the other, and that each of them
possesses the powers of serving to the
sensations of sight.
Observations of muscular movements
also tend to prove that there are two
brains. There are cases on record
which leave no doubt that either the
anterior lobe of the brain, the middle
lobe, or the posterior lobe, the three es-
sential parts Of the organ, can be de-
stroyed and voluntary movements not
be interfered with at all; but more,
there are many cases of the destruc-
ton of the whole half of the brain,
without any interference with the vol
untary movement. From this, the con-
clusion follows that we must look upon
one half of the brain as being able to
control the voluntary movements In the
two sides of the body If this be so,
the question of two brains is settled also
as regards muscular movements and
the perception of sensation. Either
half of the brain is capable of perform
ing the Office of feeling.
But the fact of greatest Importance,
as showing the doubleness of the brain,
is that its left side is the residence of
intelligence, while the right side is the
place of emotion, appetite, propensity,
etc. This proposition is an inference
from large class of facts observed by
practicing physicians. Diseases in the
left side of the brain are ofteneI
attended with manifestations of in
sanity than those in the right,
and historical and emotional symptoms
are more common in cases of disease
of the right side. There is, therefore
radical difference between the two
sides.
By such considerations as the fore.
going. DIR. Brown Sequard is convinced
of the doubleness of the brain. But
his theory would amount no more thar
a useless vagary, if he did not make q
practical application of it. He says
the difference between the two sides is
| not SO much original as dependent
upon development, and that the subject
has an educational bearing. Although
the faculty of speech in sound
healthy individuals depends upor
the left half of the brain, We
children having an affection in thai
part of the brain learn to talk, show,
ing that the right side may govern ar
] ticulation. Many other facts are giver