Abstract: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. Hum. Brain Mapping 20:22-28, 2003.

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BackgroundsRemifentanil has been reported to cause post-anesthetic shivering (PAS). Higher doses of remifentanil reportedly induce more intense PAS. Tramadol, a synthetic opioid that acts at multiple sites, is considered to be an effective treatment for PAS, but the evidence for its therapeutic benefit after remifentanil anesthesia is limited. We investigated the effect of tramadol on the incidence of PAS after remifentanil anesthesia.MethodsSixty-three patients who had undergone upper abdominal surgery under general anesthesia were studied retrospectively. Tramadol was administered at induction of anesthesia. The patients were divided into four groups: HT(+), high dose remifentanil (1–1.5 μg/kg/min) with tramadol; HT(−), high dose remifentanil without tramadol; LT(+), low dose remifentanil (0.15–0.25 μg/kg/min) with tramadol; and LT(−), low dose remifentanil without tramadol. We recorded perioperative changes in nasopharyngeal temperature and episodes of PAS on emergence from anesthesia.ResultsThe incidences of PAS in both tramadol treatment groups were significantly lower than the groups that did not receive tramadol. Nasopharyngeal temperature after surgery fell significantly more from baseline in the tramadol treatment groups compared with the non-treatment groups.ConclusionTramadol administered at induction of anesthesia appears to suppress PAS following remifentanil anesthesia.