Fluent speech with phonological paraphasia is characteristic of conduction aphasia and Wernicke's aphasia. Phonological paraphasia is characterized by speech sound errors that still convey the intended meaning. Some patients with phonological paraphasia show auditory-verbal short-term memory (STM) disturbances. However, it is not certain that phonological paraphasia results from such memory disturbances. We compared the overlapping lesions of 30 patients with phonological paraphasia, with the most relevant lesions of 38 patients with auditory-verbal STM disturbances (digit span and letter span). The results showed that the overlapping lesions of patients with phonological paraphasia were located in the subcortical white matter in the left supramarginal gyrus, regardless of the type of aphasia. The lesions most relevant to digit span disturbances were located in the subcortical white matter in the left angular gyrus, and those most relevant to letter span disturbances were located in the left superior temporal cortex. Although the lesions most relevant to phonological paraphasia and those most relevant to auditory-verbal STM disturbances were closely located, they did not correspond. These findings suggest that the cause of phonological paraphasia is not auditory-verbal STM disturbances but non-conduction of a large amount of information through underlying white matter lesions, and that two auditory-verbal STM storage sites exist in the human brain.
We investigated speech errors in Wernicke's aphasia to examine whether and what kind of errors in lexical retrieval are critical in the speech production deficit of Wernicke's aphasia in the Japanese language system. Three right-handed male patients with Wernicke's aphasia due to cerebral infarction were graded as having mild, moderate, or severe aphasia according to the Standard Language Test of Aphasia, Token Test, and Phonetic Discrimination Test. Production of words with 1 to 6 syllables was tested by having patients name objects drawn on a card, and having them repeat or read aloud words written in Kana characters. Production of words with 1 to 4 syllables was tested by having patients read aloud words written in Kanji characters. Speech errors were classified to semantic paraphasia, verbal paraphasia not semantically related to the target word, phonological paraphasia, neologism, conduites d'approche, errors of one-syllable words. Phonological paraphasias were classified as addition, omission, dislocation, or substitution. Errors of dislocation and substitution were classified as vowel or consonant errors. The more severe the aphasia, the higher was the rate of consonant errors. We suggest that impairments in consonant retrieval is critical in the speech production deficit of Wernicke's aphasia in Japanese-speaking patients.
We report the case of a patient with severe episodic amnesia who underwent a 10-year neuropsychological rehabilitation process.A 55-year-old, right-handed male developed memory disturbance following anoxia. He constantly performed above average on semantic memory test.MRI revealed cerebellar atrophy, especially in the folium vermis. Memory rehabilitation of this patient included 5 programs: a utility exercise of external memory aids, an attention training, a story recall by drawing pictures depicting the story, the 'PQRST' approach, and a couple of unrelated words recall by making a sentence including the two words. As a result, the patient's performance on memory tests (WMS-R and RBMT-J), examined repeatedly, significantly improved. Also, he became able to refer to the memory notebook and take noted.However, the patient's severe episodic amnesia remained.The internal memory strategies applied for this case did not appear effective in improving the patient's severe episodic amnesia. We speculate that the patient could learn declarative information unconsciously, as well as use of a memory notebook.
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