[Contingent negative variation prior to phonation in cleft palate-operated patients].

Abstract

In an attempt to objectively measure psychological tension suffered by cleft palate-operated patients (CPs) with speech difficulty, the contingent negative variation (CNV) was recorded in CPs and normal subjects. The CNV is an expectancy-related brain potential recorded from the surface of the head. It begins to develop after the warning signal and reaches its maximum before the imperative signal, immediately after which a specific voluntary movement is promptly executed. The maximum amplitude of CNVs and the area encircled by each CNV and its base line were measured in the vertex and the left front-parietal region (FP) during tasks of sound production (voice CNV) or finger flexion (finger CNV). Significant differences between CPs and normals were found in the following CNV parameters: 1) The FP/vertex ratio of the amplitude of finger CNVs was smaller in CPs. 2) The amplitude of voice CNVs in the FP was lower in CPs when normals uttered a Japanese vowel "a" at a relatively low intensity (60 dB) while CPs uttered "a" or the sounds most difficult for them. 3) The ratio of the amplitude of voice CNVs led from the FP to that led simultaneously from the vertex was smaller in CPs during the tasks described in 2. 4) The ratio of the area of voice CNVs in the FP to the amplitude of each CNV was greater in CPs in two cases; firstly in the task where normals uttered "a" and CPs produced the sounds most difficult for them, and secondly in the task where the subjects were asked to make the articulation at a high sound level (80 dB).(ABSTRACT TRUNCATED AT 250 WORDS)