Transcranial direct current stimulation over the right dorsolateral prefrontal cortex increases oxyhemoglobin concentration and cognitive performance dependent on cognitive load.

Transcranial direct current stimulation (tDCS) has been explored as a potential method for cognitive enhancement. tDCS may induce a cascade of neurophysiological changes including alterations in cerebral oxygenation. However, the effects of tDCS on the cognitive-cerebral oxygenation interaction remains unclear.

It's Mine, . . . It's Mine: Unsolicited Repetitions Are Reduced in Toddlers.

A phenomenon called "repetition reduction" can increase articulation rate in adults by facilitating phonetic and motor processes, which indicates flexibility in the control of articulation rate. Young children, who speak much slower, may not have the same speech motor flexibility resulting in the absence of the repetition reduction effect. In this study, we tested whether spontaneous repetitions of young children are produced with a faster articulation rate than their original utterances.

Speech kinematic variability in adults who stutter is influenced by treatment and speaking style.

Aim: We tested whether completion of the Comprehensive Stuttering Program (CSP) is associated with a reduction in speech kinematic variability relative to pre-treatment when adults who stutter (AWS) use a casual speaking manner or fluency skills.

Rational: Kinematic variability is higher in AWS suggesting a sensorimotor vulnerability; however, it is not clear whether high variability is a trait related to the underlying disorder or reflects the mutable state of stuttering. Speech restructuring intervention such as the CSP could support more consistent articulatory control and stable movement patterns.

Obtaining consensus on core components of stuttering intervention for adults: An e-Delphi Survey with key stakeholders.

Background: Evidence-based practice involves the synthesis of multiple forms of evidence to inform clinical decision-making and treatment evaluation. Practice- and patient-based evidence are two forms of evidence that are under-represented in the stuttering literature. The collection of such knowledge is essential to support the design and delivery of effective stuttering interventions for adults.

Deficit or Difference? Effects of Altered Auditory Feedback on Speech Fluency and Kinematic Variability in Adults Who Stutter.

Purpose The purpose of this study was to test whether adults who stutter (AWS) display a different range of sensitivity to delayed auditory feedback (DAF). Two experiments were conducted to assess the fluency of AWS under long-latency DAF and to test the effect of short-latency DAF on speech kinematic variability in AWS. Method In Experiment 1, 15 AWS performed a conversational speaking task under nonaltered auditory feedback and 250-ms DAF.

Early Speech Rate Development: A Longitudinal Study.

Purpose Our knowledge of speech rate development remains inadequate because of limited longitudinal data and lack of data from children under age 3;0 (years;months). The purpose of this longitudinal study was to test the pattern of speech rate development between ages 2;0 and 3;0. Method Speech rate was assessed at 4 time points between ages 2;0 and 3;0.

Theta Modulated Neural Phase Coherence Facilitates Speech Fluency in Adults Who Stutter.

Adults who stutter (AWS) display altered patterns of neural phase coherence within the speech motor system preceding disfluencies. These altered patterns may distinguish fluent speech episodes from disfluent ones. Phase coherence is relevant to the study of stuttering because it reflects neural communication within brain networks.

Delayed Phonological Encoding in Stuttering: Evidence from Eye Tracking.

Stuttering is a multifactorial disorder that is characterized by disruptions in the forward flow of speech believed to be caused by differences in the motor and linguistic systems. Several psycholinguistic theories of stuttering suggest that delayed or disrupted phonological encoding contributes to stuttered speech. However, phonological encoding remains difficult to measure without controlling for the involvement of the speech-motor system.

Suppression of vocal responses to auditory perturbation with real-time visual feedback.

Speakers can adjust pitch using auditory feedback through a short-latency corrective response known as the pitch-shift response (PSR). Suppression of the PSR denotes on-line stabilization of pitch. In this paper, the hypothesis that pitch-shift responses can be suppressed with real-time visual feedback of vocal F0 is investigated.

Cortical dynamics of disfluency in adults who stutter.

Stuttering is a disorder of speech production whose origins have been traced to the central nervous system. One of the factors that may underlie stuttering is aberrant neural miscommunication within the speech motor network. It is thus argued that disfluency (any interruption in the forward flow of speech) in adults who stutter (AWS) could be associated with anomalous cortical dynamics.

Anomaly in neural phase coherence accompanies reduced sensorimotor integration in adults who stutter.

Despite advances in our understanding of the human speech system, the neurophysiological basis of stuttering remains largely unknown. Here, it is hypothesized that the speech of adults who stutter (AWS) is susceptible to disruptions in sensorimotor integration caused by neural miscommunication within the speech motor system. Human speech unfolds over rapid timescales and relies on a distributed system of brain regions working in a parallel and synchronized manner, and a breakdown in neural communication between the putative brain regions could increase susceptibility to dysfluency.

Audio-vocal responses elicited in adult cochlear implant users.

Auditory deprivation experienced prior to receiving a cochlear implant could compromise neural connections that allow for modulation of vocalization using auditory feedback. In this report, pitch-shift stimuli were presented to adult cochlear implant users to test whether compensatory motor changes in vocal F0 could be elicited. In five of six participants, rapid adjustments in vocal F0 were detected following the stimuli, which resemble the cortically mediated pitch-shift responses observed in typical hearing individuals.

Relation of motor, linguistic and temperament factors in epidemiologic subtypes of persistent and recovered stuttering: Initial findings.

Purpose: The purpose of this study was to determine the presence of any patterns reflecting underlying subtypes of persistence and recovery across epidemiologic, motor, language, and temperament domains in the same group of children beginning to stutter and followed for several years.

Methods: Participants were 58 2-4-year-old CWS and 40 age and gender matched NFC from four different sites in the Midwest. At the end of the multi-year study, stuttering children were classified as Persistent or Recovered.

Investigating Age-related changes in fine motor control across different effectors and the impact of white matter integrity.

Changes in fine motor control that eventually compromise dexterity accompany advanced age; however there is evidence that age-related decline in motor control may not be uniform across effectors. Particularly, the role of central mechanisms in effector-specific decline has not been examined but is relevant for placing age-related motor declines into the growing literature of age-related changes in brain function. We examined sub-maximal force control across three different effectors (fingers, lips, and tongue) in 18 young and 14 older adults.

A direct comparison of short-term audiomotor and visuomotor memory.

Audiomotor and visuomotor short-term memory are required for an important variety of skilled movements but have not been compared in a direct manner previously. Audiomotor memory capacity might be greater to accommodate auditory goals that are less directly related to movement outcome than for visually guided tasks. Subjects produced continuous isometric force with the right index finger under auditory and visual feedback.

Aging effects on sensorimotor integration: a comparison of effector systems and feedback modalities.

Research on motor aging has focused on visuomotor effects in limb musculature, with few comparisons across effectors or feedback modalities. The authors examined steady fine force control in oral and manual effectors under visual and auditory feedback in 13 young (19-23 years old) and 13 older (60-77 years old) participants, hypothesizing that force variability would increase with aging (a) more in the finger than the lip and (b) for both feedback modalities. The magnitude of variability increased with age for both visuomotor and audiomotor tasks but age-related differences were greater in the lip than the finger.

Individual variability in delayed auditory feedback effects on speech fluency and rate in normally fluent adults.

Purpose: Delayed auditory feedback (DAF) is known to induce stuttering-like disfluencies (SLDs) and cause speech rate reductions in normally fluent adults, but the reason for speech disruptions is not fully known, and individual variation has not been well characterized. Studying individual variation in susceptibility to DAF may identify factors that predispose an individual to be more or less dependent on auditory feedback.

Method: Participants were 62 normally fluent adults.

Force control under auditory feedback: effector differences and audiomotor memory.

Audiomotor integration is a basic form of sensorimotor control for regulating vocal pitch and vocal loudness, but its contribution to general motor control has only been studied minimally. In this paper, auditory feedback for prolonged force control was investigated by comparing manual and oral force generation and testing short-term audiomotor memory for these effectors. Ten healthy volunteers between the ages of 20 and 30 years old were recruited.

Relationship between kinematics, F2 slope and speech intelligibility in dysarthria due to cerebral palsy.

A multimodal approach combining acoustics, intelligibility ratings, articulography and surface electromyography was used to examine the characteristics of dysarthria due to cerebral palsy (CP). CV syllables were studied by obtaining the slope of F2 transition during the diphthong, tongue-jaw kinematics during the release of the onset consonant, and the related submental muscle activities and relating these measures to speech intelligibility. The results show that larger reductions of F2 slope are correlated with lower intelligibility in CP-related dysarthria.

Audiovocal integration in adults who stutter.

Background: Altered auditory feedback can facilitate speech fluency in adults who stutter. However, other findings suggest that adults who stutter show anomalies in 'audiovocal integration', such as longer phonation reaction times to auditory stimuli and less effective pitch tracking.

Aims: To study audiovocal integration in adults who stutter using the pitch-shift paradigm.

Oral sensorimotor integration in adults who stutter.

Objective: To investigate the relationship between tendon vibration sensitivity and oral motor control in adults who stutter (AWS).

Patients And Methods: Ten controls and 10 AWS first made jaw-opening movements from a closed-mouth position to an 18-mm target. Then, masseter tendon vibration was applied during jaw opening in a separate condition to test whether accuracy and/or variability is related to movement undershoot.

Corpus callosum morphology in children who stutter.

Unlabelled: Multiple studies have reported both functional and neuroanatomical differences between adults who stutter and their normally fluent peers. However, the reasons for these differences remain unclear although some developmental data suggest that structural brain differences may be present in school-age children who stutter. In the present study, the corpus callosum of children with persistent stuttering, children who recovered from stuttering and typically developing children between 9 and 12 years of age was compared to test if the presence of aberrant callosal morphology is implicated in this disorder.

Visuomotor and audiomotor processing in continuous force production of oral and manual effectors.

The authors examined force control in oral and manual effectors as a function of sensory feedback (i.e., visual and auditory).