Evening star., 1953-11-04
Bruin Study Puts Light
On Evolution of Speech
Doctors Probe Nerve Cells
In Left Temporal Lobe
By Thomos R. Henry

The left temporal lobe Of the brain
contains two areas Of gray nerve cells
essential to human speech.
These now are being probed by stim-
ulation with electric currents by sur
geons at the National Institute Of
Neurological Diseases during the course
of operations which require that the
surface of this important and largely
unmapped part of the cerebral cortex
be exposed for long periods.
From these explorations it has
become obvious that co-ordinated
speech-this can be considered also as
including all sorts of writing and sign
language-depends on three brain CEN
ters which must act in unison.
The first, known for a long time. Is
the so-called Brocca's area located to-
ward the rear of the frontal lobe.
which controls voluntary use of the
speech muScleS-eSsentially those of
throat and tongue. The second one of
those now being probed, is called the
"nominative center" by DR.. Maitland
Baldwin, National Institute surgeon,
1t is essential for naming an object.
The third, whose cells seem all mixed
with the nominative cells, so that up to
now it has been impossible to separate
the two, is the ''semantic center" These
are located in the upper posterior part
OF the temporal lobe, the area of the
cerebral corteX just back of the ear and
lying before the So-called "fissure of
Sylvius," deep. gray-celled depression
which is the most prominent landmark
on the brains surface
Weird Effects.
The cells responsible for the differ
ent functions can be depressed by elec-
trio currents so that they will not func-
ton, and when this is done there are
some weird effects. For example. the
patient, whose brain is exposed during
the six to eight hours of the operation,
is shown some object while the nominal
tive center is put out of action. He
will try to tell the operator what he
sees.
1T is ait is at is "a" he says.
He knows perfectly we'll what the
object is, but cannot name it.
The current is removed.
This is a pencil" the patient SAYS
with no difficulty.
The needle is put in another place.
What is pencil for?" the patient
is asked.
"A pencil is fora pencil is for"
The current is removed.
"A pencil is for writing" he SAYS,
Tested on Epileptics.
This experiment is carried out at
each of the epilepsy operations, and
the results almost always are the
same. 1t is clear that two groups of
brain cells with entirely different func-
tions are in action to make possible
one simple sentence.
The patient, of course, is in COM
plete possession Of his faculties. But
bar is put up between the mental
activity involved in recognizing an OBJ
ject and that required for giving it
name. The situation would be the
same if he tried to write the word.
The sentence, obviously, represents
speech at it's simplest. Almost anything
one would want to say is much more
complicated and it is possible there
may be many more cell areas essential
for even the most casual sort of con-
verSation. No evidence of these, how
ever, has been found to date.
All responses. DR.. Baldwin explains.
must be entirely voluntary on the pa
TENTS part. There is no way of making
anybody talk by means of light stimu-
lation of speech areas. Stimulation of
the frontal lobe Brocca's area could
cause involuntary responses of the
muscles essential for talking, but the
result would be only unco-ordinated
sounds. Any intelligent communication
requires all three areas-and perhaps
some still to be discovered-in opera
ton simultaneously.
Probing the temporal lobe is of es-
pecial Importance, it is stressed, for
the light it may throw on the evolution
of speech, or the basic ability to use
words, in the ascent of man. This evo-
luton made man thinking animal,
for it is impossible to imagine anything
above the most primitive sort of
thought without words.
Historically, the temporal lobe has
been considered as the brain area of
hearing. It serves this function in the
brains of all the higher mammals. Ac-
tually, the National Institute surgeons
point out, the part reserved for hearing
in man is quite small and lies on the
outer wall of the fissure of Sylvius just
at the edge of the lobe.