Motor Speech Afferentation and the Cerebral Mechanisms of Thought

Abstract

On the basis of clinical studies of various forms of aphasia—motor and sensory disturbances of speech—the neurologists of the 19th century developed a doctrine on the presence in the cerebral cortex of speech areas, or centers, narrowly localized and independent of each other: l)the motor speech center, or Broca’s area, localized in the third frontal gyrus of the left hemisphere; 2) auditory center of speech, or Wernicke’s area, localized in the first temporal gyrus of the same hemisphere; 3) center of verbal designation, or nomination, located, according to Mills, in the lower portion of the temporal gyrus; 4) writing center, located, according to Wernicke and Exner, in the second frontal gyrus of the left hemisphere; 5) reading center, located, according to Dejerine, at the junction between the occipital and parietal lobes in the same hemisphere. Fig. 60 gives a summary of the basic clinical data on the localization of various speech disturbances, on the basis of which the above map of brain speech centers had been constructed.