Effects of linguistic correlates of stuttering on EMG activity in nonstuttering speakers

Contains fulltext : 21923___.PDF (publisher's version ) (Open Access)In this study changes in upper lip and lower lip integrated electromyographic (IEMG) amplitude and temporal measures related to linguistic factors known for their influence on stuttering were investigated. Nonstuttering subjects first read and then verbalized sentences of varying length (sentence length factor), in which meaningless but phonologically appropriate character strings were varied in their position within the sentence (word position factor) and their size (word size factor). It was hypothesized that the production of stressed, vowel-rounding gestures of words in initial position, longer words, and words in longer sentences would be characterized by specific changes in IEMG amplitude that would reflect an increase in speech motor demands, intuitively defined as articulatory effort. Basically, the findings corroborated our assumptions, showing that words in sentence initial position have shorter word and vowel durations in combination with an increase in IEMG activity. Similarly, we found shorter vowel durations for longer words, and in sentence final position an increase in IEMG activity. For longer sentences we found a clear increase in speech rate, but contrary to our expectations a decrease in IEMG activity. It was speculated that this might relate to the use of a movement reduction strategy to allow higher speech rates with increased coarticulation. These findings were discussed both for their implications in normal speech production, as well as for their possible implications for explaining stuttering behavior. To this end our data can illustrate both why stutterers might run a higher risk of stuttering at these linguistic loci of stuttering, and why they might come up with a strategic solution to decrease the motor demands in speech production. The basic outcome of this study shows that higher order (linguistic) specifications can have clear effects on speech motor production

From planning to articulation in speech production: What differentiates a person who stutters from a person who does not stutter?

Contains fulltext : 23922___.PDF (publisher's version ) (Open Access)The main purpose of the present study was to differentiate between people who stutter and control speakers regarding their ability to assemble motor plans and to prepare (and execute) muscle commands. Adult males who stutter, matched for age, gender, and educational level with a group of control speakers, were tested on naming words and symbols. In addition, their ability to encode and retrieve memory representations of combinations of a symbol and a word, was tested in a recognition task, using manual reaction times and sensitivity scores, as defined in signal detection theory, as performance measures. Group differences in muscle command preparation were assessed from electromyographic recordings of upper lip and lower lip. Results indicated no interaction between group and word size effects in choice reaction times or a group effect in the ability to recognize previously learned symbol-word combinations. However, they were significantly different in the timing of peak amplitudes in the integrated electromyographic signals of upper lip and lower lip (IEMG peak latency). Findings question the claim that people who stutter have problems in creating abstract motor plans for speech. n addition, it is argued that the group differences in IEMG peak latency that were found in the present study might be better understood in terms of motor control strategies than in terms of motor control deficits

Effects of simvastatin on hepatic cholesterol metabolism, bile lithogenicity and bile acid hydrophobicity in patients with gallstones

Background and Aims: There is limited information available on the effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on hepatic and biliary cholesterol metabolism in patients with gallstones. The aims of this study were to determine the effect of simvastatin on the regulatory elements of cholesterol metabolism that determine the concentrations of cholesterol in plasma and bile. Methods: Thirty-one gallstone patients were enrolled in the study; 17 were treated with 20 mg simvastatin daily for 3 weeks prior to cholecystectomy and 14 served as controls. Samples of blood, liver, gall-bladder bile and bile from the common bile duct (CBD) were collected and analysed. Results: The plasma cholesterol (-30%), triacylglycerol (-23%) and low-density lipoprotein (LDL) cholesterol (-42%) concentrations were significantly lowered by simvastatin treatment, as was the plasma lathosterol: cholesterol (-70%), which reflects whole-body cholesterol synthesis. Despite these changes, the hepatic LDL receptor protein and LDL receptor activity in circulating mononuclear cells were similar in both groups. There were no differences in the plasma phytosterol: cholesterol, which reflects the intestinal cholesterol absorption capacity or in the activity of hepatic acyl-coenzyme A: cholesterol acyltransferase. There were however, lower cholesterol concentrations in CBD (-68%) and gall bladder (-41%) bile, and decreased lithogenic (-47%) and bile acid hydrophobicity (-22%) indices of CBD bile in the simvastatin group. Conclusions: These data indicate that simvastatin reduced plasma and biliary cholesterol levels primarily by reducing cholesterol synthesis. The reduction in CBD bile lithogenicity and bile acid hydrophobicity by simvastatin suggests that this agent may be useful for people who have early stages of cholesterol gallstone development and in whom a choleretic effect is required. (C) 2000 Blackwell Science Asia Pty Ltd