Functional organization of the auditory cortex is different in stutterers and fluent speakers

Impaired auditory feedback has been suggested to cause stuttering, and subtle irregularities of audition have been reported in behavioural studies. To characterize processing at the auditory cortical level, we recorded neuromagnetic responses to monaural tones in nine stutterers and 10 fluent speakers while the subjects were reading silently, with mouth movements only, aloud, and in chorus with another person. The basic functional organization of the auditory cortices was found to be different in stutterers and controls. The altered interhemispheric balance in stutterers was affected by speech production, due to changes in the left auditory cortical representation, and more severely by self-paced than accompanied speech. This may lead to transient non-optimal interpretation of the auditory input and affect speech fluency.     

Stuttering: a brief review

The etiology of stuttering is controversial. The prevailing theories point to measurable neurophysical dysfunctions that disrupt the precise timing required to produce speech. Stuttering is a common disorder that usually resolves by adulthood. Almost 80 percent of children who stutter recover fluency by the age of 16 years. Mild stuttering is self-limited, but more severe stuttering requires speech therapy which is the mainstay of treatment. Delayed auditory feedback and computer-assisted training are currently used to help slow down speech and control other speech mechanisms. Pharmacologic therapy is seldom used, although haloperidol has been somewhat effective.     

Adaptation of stuttering frequency during repeated readings: associated changes in acoustic parameters of perceptually fluent speech

This study is part of a series investigating the hypothesis that stuttering adaptation is a result of motor learning. Previous investigations indicate that nonspeech motor learning typically is associated with an increase in speed of performance. Previous investigations of stuttering, on the other hand, indicate that improvements in fluency during most fluency-enhancing conditions or after stuttering treatment tend to be associated with decreased speech rate, increased duration of specific acoustic segments, and decreased vowel duration variability. The present acoustic findings, obtained from 8 individuals who stutter, reveal that speech adjustments occurring during adaptation differ from those reported for other fluency-enhancing conditions or stuttering treatment. Instead, the observed changes are consistent with those occurring during skill improvements for nonspeech motor tasks and, thus, with a motor learning hypothesis of stuttering adaptation. During the last of 6 repeated readings, a statistically significant increase in articulation rate was observed, together with a decrease in word duration, vowel duration, and consonant-vowel (CV) transition extent. Other adjustments showing relatively consistent trends across individual subjects included decreased CV transition rate and duration, and increased variability of both CV transition extent and vowel duration.     

Stutterers' perceptions of therapy improvement and of posttherapy regression: effects of certain program modifications

In an attempt to improve its effectiveness, a traditional, symptomatic stuttering therapy program for school-age children was modified to (1) focus more upon self-therapy activities while reducing group work emphasis; (2) specify more precisely the target responses used to replace stuttering; (3) establish clearly the criteria for client progress; and (4) provide well-defined activities for the transfer of speech change. Participants used a questionnaire to evaluate their improvement and post-therapy regression in various dimensions of stuttering severity, and results were compared with questionnaire findings from an earlier treatment program. Significantly greater improvement in speech fluency was perceived by the participants following the modified program, and follow-up videotape samples confirmed their perceptions as revealed on the questionnaire.     

Effect of biofeedback-based relaxation on stuttering during reading and spontaneous speech.

Conducted 3 studies to develop methodology for using biofeedback to reduce stuttering by teaching relaxation of speech-related muscles. A total of 19 stutterers (mean ages 22.1–24.6 yrs) participated in 8–25 1-hr sessions. In Study 1, 7 Ss learned voluntary relaxation of the masseter muscles, and stuttering was essentially eliminated while reading units of 1–4 syllables. Study 2 attempted to enhance the generalization of fluency by training 6 Ss to develop their own internal cues for relaxation. Fluency generalized well to periods of no feedback, but relaxation generalized much less well. In Study 3, which specifically attempted to enhance the generalization of relaxation, 6 Ss were successfully trained to generalize both relaxation and fluency skills to spontaneous speech periods of up to 4-word units involving no feedback. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetitive speech disorder resulting from infarcts in the paramedian thalami and midbrain

A repetitive speech disorder resulting from infarcts in the paramedian thalami and the midbrain is reported. Although the speech disorder seemed like stuttering, the compulsive repetitions, constant rate and monotonous tone were not associated with ordinary stuttering. Since repetition was restricted to the first syllable, the speech disorder in our patient could be distinguished from palilalia. The extrapyramidal system is considered responsible for repetitive speech disorders resulting from infarcts in the paramedian thalami and the midbrain but without good reason. Repetitive speech disorder in patients with infarcts in the supplementary motor area (SMA) have similar clinical features to our patient. It is suggested that interruption in the projective system to the SMA is a possible cause of "stuttering like repetition".     

Cytotoxicity and NMR spectral assignments of ergolide and bigelovin

A 10-year-old left-handed girl with a developmental stutter and agenesis of the corpus callosum with associated hydrocephalus ceased stuttering immediately upon initiation of steroid therapy for colitis. Steroid taper resulted in a recurrence of the stutter and resumption for treatment of recrudescent colitis caused its disappearance again. Baseline agenesis of the corpus callosum with hydrocephalus and the patient's course in the face of the known effects of steroids on white matter lend support to the hypothesis that stuttering reflects anomalous dominance and/or atypical interhemispheric connectivity, as evidenced by the fact that presumed alterations of white matter tracts affected speech rhythms/stuttering.     

Changes in stuttering frequency as a function of various intervals of delayed auditory feedback.

5 different intervals of delayed auditory feedback (DAF) were presented to 6 severe stutterers while they read aloud. Results indicate that the continuous presentation of DAF significantly reduced stuttering frequency. Fluency enhancement was generally greatest during the shortest DAF intervals tested. No evidence was found for the carryover of fluency generated by DAF into the period immediately following Ss' experience on DAF. Results are consistent with a view that stuttering is based on a defect in the processing of auditory feedback. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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

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.     

The relevance of audio-visual feedback mechanisms in the acquisition of reading skills.

There has been much confusion in the past on the topic of reading disabilities. The distinction is made between acquired cases of dyslexia where a previously acquired language skill is lost as the result of injury, disease or trauma to the central nervous system and cases of a more congenital nature where children seem to find it very difficult to acquire the normal reading skills. The study of acquired dyslexia has thrown much light on the various brain centra involved in all the complex language skills of which reading and writing is but one aspect. The cases of congenital dyslexia which are encountered frequently in all schools more than likely have little evidence of brain damage. Rather, a development lag or neurological disorganization seems to be at the root of such troubles. The importance of cerebral laterality for speech and language skills is being realized. In particular it appears that auditory dominance, an aspect of laterality that is still being investigated, is extremely important in the acquisition and execution of language skills. When a subject's voice is picked up by a microphone, delayed for .2" and then fed back to the subject via earphones the subject begins to stutter. Under certain conditions it is possible to demonstrate that the subject's speech will be more impaired when this delayed feedback is on his dominant ear than when it is on his non-dominant ear suggesting an assymetry of the monitoring functions of the two ears. This finding, if further investigated and validated, may have far reaching consequences in the remediation of language disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of contingent events on stuttering and fluency.

In Study 1 with 4 male 18-20 yr old stutterers, the effect on stuttering frequency of contingent monetary gain and contingent monetary loss for stuttering was examined individually for over 12 hrs, using control periods when no contingency was present. Both contingencies resulted in decreased stuttering, suggesting that the effect of observing and recording instances of stuttering was more powerful than the money. In Study 2, monetary gain and loss was made contingent on units of fluent speech for 5 male and 1 female 17-34 yr old stutterers over 12 hrs. Fluency increased for the group during monetary gain, but monetary loss did not have the predicted effect of decreasing fluency, perhaps because the contigent events served also to enhance self-observation. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two- to six-year controlled-trial stuttering outcomes for children and adolescents

This research is a long-term follow-up of a previously published, controlled trial on the effectiveness of 3 stuttering treatments (intensive smooth speech, parent-home smooth speech, and intensive electromyography feedback) for children and adolescents, aged 11 to 18 years, who stutter. The previous controlled trial showed all 3 treatments to be effective compared to nontreatment after 12 months. This paper reports on the treatment effectiveness after an average of 4 years post-treatment. Results demonstrate that treatment gains were maintained in the long term, with rates of stuttering similar to the 1-year postoutcomes. There were no significant differences among the 3 treatments in long-term effectiveness. This controlled study substantiates the claim that the treatments investigated will more than likely have substantial long-term benefits for the fluency and personality of children and adolescents who stutter.     

Justification for visceral angiography prior to pancreaticoduodenectomy

Acquired stuttering resulting from a striatocapsular infarction is reported. A 54-year-old man was admitted to our hospital because of acute onset of stuttering and right facial palsy. The patient spoke very slowly. Speech was characterized by repetitions and prolongations. We considered that there was no aphasia, because comprehensive faculty was normal and neither paraphasia nor word-finding difficulty was recognized. Brain CTs and MRI revealed a striatocapsular infarction extending from the putamen to the caudate nucleus in the left hemisphere. Previously, there were reports of stuttering derived from parkinsonism and lesions in the supplementary motor area and thalamus. Therefore, we proposed that the stuttering arose from a collapse of basal ganglia circuits that connect the cerebral cortex and basal ganglia, including the extrapyramidal tract system.     

Sex differences in oral asymmetries during wordrepetition

During speech production the right side of the mouth is opened to a larger degree in most people. This facial asymmetry is thought to be related to a left hemisphere dominance in language processing and/or motor programming. We investigated asymmetrical lip separations during discrete or serial word productions in right handed persons. The results revealed a right sided lip separation bias in both genders during discrete word production in which the words had to be uttered once. As soon as the words had to be produced continuously, however, a clear sex difference appeared with males having the usual right bias but females now showing no clear asymmetry, with a tendency for larger lip separations on the left side. These results suggest the existence of two separate neural systems from which one controls the discrete task and which is left hemisphere dominant in both genders. The other is probably involved in serial word productions and shows a sex difference with regard to its asymmetry pattern.     

Functional speech system disorder in stuttering]

The author studied the EMG or orbicular muscles of the mouth, respiration, pulse frequency, SGR, EEG registration during the pronunciation of words out loud and to onself, during the orientation reflex to sound and verbal stimuli. These indices were mainly studied during autogenic training in patients with neurotic stuttering (the 1st group) and in patients with organic lesions of the CNS and stuttering (the 2nd group). The first group of patients demonstrated formed motor verbal sterotypes. A disturbance of the correct programme of action in the functional speech system is due to an increase of the activity in the limbico-reticular system. The 2nd group exhibits the absence of the correct programme of action in the accomplishment of motor speech stereotypes. The abnormal programme of the activity is formed from the beginning of the speech activity and is fixed in the ontogenetical memory.     

Analyse des traitements behavioraux du bégaiement.

Discusses the relative efficacy of behavioral treatments of stuttering. Rythmic stimulation, delayed auditory feedback and prolonged speech, masking and shadowing, operant conditioning, and systematic desensitization all reduce stuttering. Rarely, though, do any of these therapeutic strategies produce normally fluent speech. (English abstract) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

An overview of neural function and feedback control in human communication

The speech and hearing mechanisms depend on accurate sensory information and intact feedback mechanisms to facilitate communication. This article provides a brief overview of some components of the nervous system important for human communication and some electrophysiological methods used to measure cortical function in humans. An overview of automatic control and feedback mechanisms in general and as they pertain to the speech motor system and control of the hearing periphery is also presented, along with a discussion of how the speech and auditory systems interact.     

A theoretical investigation of reference frames for the planning of speech movements.

Does the speech motor control system use invariant vocal tract shape targets when producing vowels and semivowels? A 4-part theoretical treatment favoring models whose only invariant targets are regions in auditory perceptual space over models that posit invariant constriction targets is presented. Auditory target regions are hypothesized to arise during development as an emergent property of neural map formation in the auditory system. Furthermore, speech movements are planned as trajectories in auditory perceptual space. These trajectories are then mapped into articulator movements through a neural mapping that allows motor equivalent variability in constriction locations and degrees when needed. These hypotheses are illustrated using computer simulations of the DIVA model of speech acquisition and production. Finally, several difficult challenges to proponents of constriction theories based on this theoretical treatment are posed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Speech impairment in Parkinson's disease is improved by transcranial application of electromagnetic fields

A 52 year old fully medicated physician with juvenile onset Parkinsonism experienced 4 years ago severe "on-off" fluctuations in motor disability and debilitating speech impairment with severe stuttering which occurred predominantly during "on-off" periods. His speech impairment improved 20%-30% when sertraline (75 mg/day), a serotonin reuptake inhibitor, was added to his dopaminergic medications which included levodopa, amantadine, selegiline and pergolide mesylate. A more dramatic and consistent improvement in his speech occurred over the past 4 years during which time the patient received, on a fairly regular basis, weekly transcranial treatments with AC pulsed electromagnetic fields (EMFs) of picotesla flux density. Recurrence of speech impairment was observed on several occasions when regular treatments with EMFs were temporarily discontinued. These findings demonstrate that AC pulsed applications of picotesla flux density EMFs may offer a nonpharmacologic approach to the management of speech disturbances in Parkinsonism. Furthermore, this case implicates cerebral serotonergic deficiency in the pathogenesis of Parkinsonian speech impairment which affects more than 50% of patients. It is believed that pulsed applications of EMFs improved this patient's speech impairment through the facilitation of serotonergic transmission which may have occurred in part through a synergistic interaction with sertraline.