The neuroradiological considerations about the site of lesions and pathomechanisms of classical aphasic syndrome caused by brain infarction were discussed. In this paper, I gave case studies of some aphasic patients with lesion in the left frontal lobe, with lesion producing conduction aphasia, and with borderzone infarction. (1) The cases of aphasia with left frontal lobe. The patient of pure word dumbness showed the infarction of the precentral gyrus. The aphasic patients who have the lesion of Broca's area presented transcortical sensory aphasia. Motor aphasia occurred with the lesion including both Broca's area and precentral gyrus. Transcortical motor aphasia was observed next to the lesions surrouding Broca's area, or medial portion of the frontal lobe which was perfused by anterior cerebral artery. (2) The site of lesion producing conduction aphasia. The lesion producing conduction aphasia is located mainly in supramarginal gyrus. The lesion of the postcentral gyrus has also the possibility of producing conduction aphasia. (3) The clinical significance of borderzone infarction. Superficial borderzone infarction may cause transcortical aphasia. Anterior type borderzone infarction will produce transcortical motor aphasia, and the case of the posterior type may present transcortical sensory aphasia. Deep borderzone infarction due to left caroid artery occlusion may produce severe aphasia. The marked reduction of cerebral blood flow and metabolism in the left cerebral hemisphere will be observed in these cases.

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  We reported a right-handed woman in her fifties who showed repetitive speech and omission of postposition-al particles and ends of words and sentences after right putaminal hemorrhage.
  Since she showed repetition of words and syllables at the same ratio, we diagnosed palilalia with acquired stuttering. We gave her speech therapy using the mora-by-mora method with finger-counting gestures, which was effective in decreasing both her palilalia and omission phenomenon but only temporarily effective in decreasing her acquired stuttering.
  We discussed the following three points :
 (1) Her repetitive speech might have been caused by diffuse dysfunction of the entire right hemisphere including the frontal lobe. This might have caused a breakdown of the inhibitory mechanisms of speech and/or deficits in coordination of speech movements that may be achieved through integration of both hemispheres.
 (2) Omission phenomenon might be related to her severe attentional disorders and impatience in performing actions(impediment in pacing).
 (3) Indifference to her speech disorders might contribute to her repetitive speech and omission phenomenon.

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  A Sentence Forming Test has been developed as a quantitative and qualitative assessment tool for subjects' ability to formulate communicative utterances with characteristics of natural conversation. Thirty-three pairs of words with various degrees of semantic distances were used to elicit utterances. All words had high familiarity. Each pair was presented in writing and subjects were asked to form and orally express a sentence using these words.
  The present study obtained data from 120 normal adults to determine central tendencies and variabilities of normal performances and to examine validity of the test. Attempts were also made to establish criteria for quantifying infinitive expressions, which often occur in Japanese conversation.
  The results indicated that the distribution of normal responses (Mean=30.4, and SD=1.5) approximated the left half of normal distribution. The responses were characterized by a wide range of vocabulary and various syntactic structures, reflecting idiosyncrasy among subjects. Two criteria, “frequent appearance in responses of normal adults” and “meanings can be guessed from the context”, were found to be effective in determining adequacy of responses.

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