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Yasuki Hashimoto

Publications and source records attributed to Yasuki Hashimoto.

3 recordsLinked to original sources
PubMed2003

Brain activations during conscious self-monitoring of speech production with delayed auditory feedback: an fMRI study.

When a speaker's voice returns to one's own ears with a 200-ms delay, the delay causes the speaker to speak less fluently. This phenomenon is called a delayed auditory feedback (DAF) effect. To investigate neural mechanisms of speech processing through the DAF effect, we conducted a functional magnetic resonance imaging (fMRI) experiment, in which we designed a paradigm to explore the conscious overt-speech processing and the automatic overt-speech processing separately, while reducing articulatory motion artifacts. The subjects were instructed to (1) read aloud visually presented sentences under real-time auditory feedback (NORMAL), (2) read aloud rapidly under real-time auditory feedback (FAST), (3) read aloud slowly under real-time auditory feedback (SLOW), and (4) read aloud under DAF (DELAY). In the contrasts of DELAY-NORMAL, DELAY-FAST, and DELAY-SLOW, the bilateral superior temporal gyrus (STG), the supramarginal gyrus (SMG), and the middle temporal gyrus (MTG) showed significant activation. Moreover, we found that the STG activation was correlated with the degree of DAF effect for all subjects. Because the temporo-parietal regions did not show significant activation in the comparisons among NORMAL, FAST, and SLOW conditions, we can exclude the possibility that its activation is due to speech rates or enhanced attention to altered speech sounds. These results suggest that the temporo-parietal regions function as a conscious self-monitoring system to support an automatic speech production system.

Acoustic Stimulation↗
PubMed2002

Peritoneal equilibration test at home.

The peritoneal equilibration test (PET) has been widely used as a standardized means for estimating solute transport. However, the procedure is rather complex, and patients must spend more than half a day in the hospital. The fast PET is an alternative method, but the results are not reliable in patients whose peritoneal catheters drain poorly. We postulated that patients could perform the PET at home if educated well about the procedure. To that purpose, we prepared three types of visual aids that introduce the PET procedure: a VCR tape, a DVD disc, and a brochure with photographs. Equilibration tests were performed using the twin-bag system. For making fluid level indicator lines (200 mL and 10 mL), patients are given a guide sheet on which the fresh dialysate bag is placed. After an 8- to 12-hour overnight dwell, the dwelled dialysate is drained completely into the empty bag. Immediately after the patient infuses 2 L of fresh 2.5% glucose dialysis solution, 200 mL of that solution is drained into the bag on which the two fluids levels were previously marked. After mixing, about 190 mL of the dialysate is re-infused, and the remaining 10 mL (the amount indicated by a guide mark at the corner) is left within the bag. After a 4-hour dwell, the dialysate is completely drained into another twin-bag. A standard PET was also performed on a different day, and the data were compared with those from the home PET. Significant correlations were seen in D/D0 and in drain volume between the home PET and the standard PET (n = 10; D/D0: 0.385 +/- 0.054 vs. 0.371 +/- 0.052 respectively, r = 0.872, p = 0.0004; drain volume: 2340 +/- 123 mL vs. 2372 +/- 90 mL respectively, r = 0.788, p = 0.0048). We conclude that the home PET is a clinically useful alternative to the standard PET, saving time and labor while maintaining accuracy.

Adult↗