| Research Abstract |
Neural networks for speech may be subdivided into two stages, such as the imaginary and executive stages, and products from these stages are called covert and overt speech, respectively. On the other hand, subjects with cleft lip and palate (CLP) axe known to show impaired speech, or compensatory misarticulation. Previous studies showed that these were significant differences between subjects with and without CLP in 1) the activated pattern in the brain during articulation (Shinagawa, et al., 2006), and 2) the movement pattern of the articulators (Sato-Wakabayashi, et al., 2008). However, the responsible stage for the difference in articulation between those with and without CLP was unknown. Adult subjects with [unilateral (UCLP) and bilateral (BCLP)l and without CLP were recruited. We used a 1.5 T MR apparatus. Functional MRI data were taken while the subject repeated the velar plosive, /ka/, at 1.5 Hz for either covert (C) or overt (O) speech in the block design SPM2 was used for analysis. It was shown that the premotor area was activated during C speech in subjects with and without CLP. During O speech, the premotor area, the primary motor cortex and the cerebellum were activated in subjects with UCLP and those without CLP,. On the other hand, these areas were not activated but the posterior cingulate gyrus was activated in the subject with BCLP. These findings suggest that there seems to be little difference in the imaginary stage, but there are differences in the executive stage for articulation between subjects with and without CLP. It appears that several factors including types of the cleft, the difference in the motor outputs and sensory inputs, the types and severity of misarticulation and the timing and effect of speech therapy maybe involved in the difference.
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