The evening times., 1899-10-17
LoCALIzINe BRAIN FUNCTION.
An improvements in Methods Of In
vestiEatiOn.
(From the pbiladeInhia Me-

(From the Philadelphia Medical Journall
| For some time il has been recognized
that the results obtained by experiments in
cerebral iocalization which are carried out
on animals under anaesthcsia are not alto
getEer reliable or accurate. 1t is rot pos
sibfe 10 say that the results obtained by
/ stimulating the cerebral cortex of an ami
! nal benumbed by an anaesthetic and more
or less bound 10 an operating table are the
same that would result from the applca-
tiOn Of the same stimulus to the brain of
an animal in its normal condition and free
to move in any way ct wi l; il fact an
animal under anaesthesia is in many re-
spects entirely unsuitable for any exact
experimentation in cerebral locaiiZation-
To overcome this difficulty Prof. Richard
EWald, of Strasburg, has devised an ivory
plug which can be screwed permanently
into the skull of the animal upon which 4
is desired to experiment. and in these
plugs are fastened electrodes which rest
upon the brain and which may be at any
| time connected with battery. The inser-
tion of the plugs is a comp Iaratively sim
pie matter the animal is anaesthetized.
trepanning is performed under tie usual
aseptic precautions, the plug carrying the
electrodes is screwed in place, and the
muscles and skin are sswed over the plug,
leaving only the small wires prCtruding
which are to be connected with the bat
! terry. The animal is soon up and about,
and apparently as comfortable and as hap
py as ever. AS would Be expected from
the we'll known use OF ivory pegs in bone
surgery and tie filing of defects with
bone chips the ivory plugs produce abso-
lutely 10 irritation, and would no doubt
in time become incorporated into the skull
as is seen in the changes which tcke piac9
after they are left in position for some
time. Talbert, an American student in
Hermann Munk's laboratory at Berlin, is
carrying on an extensive ssries of careful
experimental studies in this line of work.
One great advantage OF this method OF
study is the case with which experiments
in cerebral localiZatiou may be shown 10
classes of students. Animals, preferably
dogs, may be operated upon al the conye-
nience of the teacher. ard after their re-
covery they may be brought at any time
before the class for purposes of demon
stration, il being only necessary TO con-
meet the electrodes in the ivory plugs with
a suitable battery. AS to the results of
experimentation, it has been determined
that the animal has no real appreciation
of the stimulation, but he reacts only by
muscular contraction and in no other way,
and, as far as can be observed, suffers no
discomfort from the experimentation.
AS a second result, it seems to be deter
mined that there exists absolutely no area
in the cerebral cortex from which it is not
possible to get a response TO electrical
stimulation by muscle contraction. The To-
cation of the most important motor areas
has been long known, but we believe that
the fact that every area of the cortex has
its connection with some muscle Or mus
cles has not been recognized.
Another interesting fact is that the re-
suits of stimulation vary with posture of
the animal at the time of the experiment.
Thus, to bring out certain contraction
Of the muscle group the strongest stimu-
ius was needed when the animal was ly-
ing On the belly: second, in standing
third, in sitting. and the weakest while he
was lying on his back. The only expla-
nation thought to be somewhat plausible
is that the contraction OF the muscles of
the extremity while supporting the body
may act in scme way to inhibit the motor
impulses.
A number of other questions of interest
have come up during this series of expe-
riments which it is impossible tc consider
in this place. 1t may be said that while
there seems to be no prospect that this
improvement will reyolutionize the pres
ent knowledge, there can be no doubt that
it is valuable addition to our methods
of study in this interesting and impor-
tant field of investigation.