We need to understand aphasia in terms of two points of view. One is the viewpoint of system of language, and the other is the viewpoint of brain function. Language systems are hierarchically constructed, for instance, acoustic system (hearing and speech), phonetic system (discrimination of language sounds and articulation control), phonemic system and lexical/semantic system. Language impairments can be developed of each system as language symptoms. And there are corresponding lesion sites in the brain for each elementary language symptoms such as anarthrie/apraxia of speech, impairment of discrimination of language sound (word deafness), phonemic paraphasia, word comprehension impairment, word retrieval impairment and so on. Classical aphasia classification are vascular syndromes and can be explained as the syndromes made of the elementary symptoms.
This paper reports evaluation of lateralization of vowel and prosody processing in the auditory areas using candle-like dry microneedle electrodes, which can acquire high-quality electroencephalogram (EEG) from hairy parts without any pretreatment. In our previous work, we successfully measured spontaneous potential and even-related potential (ERP) and proved the effectiveness as EEG electrodes. In this work, we demonstrate measurement of lateralization by the simultaneous measurement of EEG and hemodynamics, using the candle-like dry microneedle electrodes and Near infrared spectroscopy (NIRS). oddball tasks using 3 stimuli and speech stimuli were assigned to the subjects, where EEG and Oxy-Hb concentration were acquired from the temporal region (T3, T4 in international 10-20 system). As a result, the lateralization was measured in EEG and oxy-Hb concentration from several subjects.