90 Chapter 5
Aphasia has existed presumably since humans began to talk. In the mid-1800s, two neurolo-
gists identified parts of the brain impor tant to communication. Paul Broca, a French physician,
discovered that the left side of the brain controls speech. In 1865, he made this now- famous state-
ment: “We speak with the left hemi sphere.” Later, a German physician, Karl Wernicke, discovered
that the left hemi sphere is impor tant to understanding speech. Today, the area of the brain impor-
tant for expressive communication is called Broca’s area, and We r nick e’s area is its receptive coun-
terpart. Together, these sites are considered the major speech and language centers of the brain.
Figure 5-1 shows the major speech and language regions of the left hemi sphere of the brain found
in the majority of (but not all) persons.
Although certain sites of the brain have been identified as impor tant to expressive and recep-
tive communication, the brain operates as a whole. No part of the brain is completely in de pen dent
from the others. In addition, there is considerable anatomical variation among individuals in the
areas for speech and language. In fact, in some persons the left hemi sphere is not dominant for
language. According to Zemlin (1998) and Restak (1984), the left hemi sphere is specialized for
language, handedness, analytic thought pro cesses, and certain types of memory in about 90% of
right- handed persons and about 60% of left- handed persons. In those who are ambidextrous, the
left hemi sphere is dominant in about 60%, and both brain hemi spheres are equally dominant in
some. Especially in regard to language, it is difficult to localize one area of the brain as totally
responsible for a par tic u lar function in all persons.
Figure 5-1. Split brain and approximate
sites of major speech and hearing land-
marks.