It is true that in the overwhelming majority of right-handers, language is
found in the left hemisphere. It is also true that when the left hemisphere
is damaged, the right hemisphere probably participates in the recovery of
language function. But there is serious question of how much the right
hemisphere is capable of taking over language function. Some of the more
dramatic evidence of its limitations in this respect comes from
left hemispherectomies and commissurotomies. According to Marquardt 1982,
"The immediate effect of a left hemispherectomy is to render the patient
severely aphasic with auditory comprehension limited to perhaps only the
ability to follow simple commands. Performance in comprehension appears
to improve with time, but production is severely limited. Commissurotomized
patients have been used to investigate capacities and functions of the right
hemisphere. In general these split brain subjects never appear to develop
language in the right hemisphere beyond the ability to carry out some simple
commands and to recognize objects and assign names to them. These
nonexpressive functions and some small amount of automatic speech, such as
cursing and counting, are all that can confidently be attributed to the
right hemisphere."
Some aphasia research does support a right hemisphere role in recovery of
language- e.g., patients who become aphasic following a left hemisphere
stroke, recover, then become aphasic again following a right hemisphere
stroke. There are also patients who suffer a left hemisphere stroke,
become aphasic, recover, suffer another left hemiphere stroke, and become
aphasic again, however. Some case studies: Nielsen (1946), Geschwind (1974).
Lisa J. Harris
Doctoral Student, Speech Pathology
