Knowns and unknowns about the neurobiology of stuttering.

Stuttering occurs in early childhood during a dynamic phase of brain and behavioral development. The latest studies examining children at ages close to this critical developmental period have identified early brain alterations that are most likely linked to stuttering, while spontaneous recovery appears related to increased inter-area connectivity. By contrast, therapy-driven improvement in adults is associated with a functional reorganization within and beyond the speech network.

Dissecting structural connectivity of the left and right inferior frontal cortex in children who stutter.

Inferior frontal cortex pars opercularis (IFCop) features a distinct cerebral dominance and vast functional heterogeneity. Left and right IFCop are implicated in developmental stuttering. Weak left IFCop connections and divergent connectivity of hyperactive right IFCop regions have been related to impeded speech.

White matter tract strength correlates with therapy outcome in persistent developmental stuttering.

Persistent stuttering is a prevalent neurodevelopmental speech disorder, which presents with involuntary speech blocks, sound and syllable repetitions, and sound prolongations. Affected individuals often struggle with negative feelings, elevated anxiety, and low self-esteem. Neuroimaging studies frequently link persistent stuttering with cortical alterations and dysfunctional cortico-basal ganglia-thalamocortical loops; dMRI data also point toward connectivity changes of the superior longitudinal fasciculus (SLF) and the frontal aslant tract (FAT).

Stuttering severity relates to frontotemporal low-beta synchronization during pre-speech preparation.

Objective: The neurophysiological dynamics of the occurrence of a stuttering event are largely unknown. This sensor-level EEG study investigated whether already the intention to speak alters the formation of the speech production network in stuttering.

Methods: We studied alpha (8-13 Hz), low beta (15-25 Hz) and high beta (25-30 Hz) power modulation in 19 adults with developmental stuttering (AWS) and 19 fluently speaking control participants during speech intention.

Fluency shaping increases integration of the command-to-execution and the auditory-to-motor pathways in persistent developmental stuttering.

Fluency-shaping enhances the speech fluency of persons who stutter, yet underlying conditions and neuroplasticity-related mechanisms are largely unknown. While speech production-related brain activity in stuttering is well studied, it is unclear whether therapy repairs networks of altered sensorimotor integration, imprecise neural timing and sequencing, faulty error monitoring, or insufficient speech planning. Here, we tested the impact of one-year fluency-shaping therapy on resting-state fMRI connectivity within sets of brain regions subserving these speech functions.

Two cortical representations of voice control are differentially involved in speech fluency.

Recent studies have identified two distinct cortical representations of voice control in humans, the ventral and the dorsal laryngeal motor cortex. Strikingly, while persistent developmental stuttering has been linked to a white-matter deficit in the ventral laryngeal motor cortex, intensive fluency-shaping intervention modulated the functional connectivity of the dorsal laryngeal motor cortical network. Currently, it is unknown whether the underlying structural network organization of these two laryngeal representations is distinct or differently shaped by stuttering intervention.

Differentiation of brain metastases from small and non-small lung cancers using apparent diffusion coefficient (ADC) maps.

Background: Brain metastases are particularly common in patients with small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with NSCLC showing a less  aggressive clinical course and lower chemo- and radio sensitivity compared to SCLC. Early adequate therapy is highly desirable and depends on a reliable classification of tumor type. The apparent diffusion coefficient is a noninvasive neuroimaging marker with the potential to differentiate between major histological subtypes.

Enlarged Area of Mesencephalic Iron Deposits in Adults Who Stutter.

Purpose: Childhood onset speech fluency disorder (stuttering) is possibly related to dopaminergic dysfunction. Mesencephalic hyperechogenicity (ME) detected by transcranial ultrasound (TCS) might be seen as an indirect marker of dopaminergic dysfunction. We here determined whether adults who stutter since childhood (AWS) show ME.

Speech restructuring group treatment for 6-to-9-year-old children who stutter: A therapeutic trial.

For children who stutter (CWS), there is good evidence of the benefits of treatment for pre-school age, but an evidence gap for elementary school age. Here we report on the effectiveness of a fluency shaping treatment for 6- to 9-year-old children. The main treatment component is the reinforcement of soft voice onsets.

Auditory brainstem measures and genotyping boost the prediction of literacy: A longitudinal study on early markers of dyslexia.

Literacy acquisition is impaired in children with developmental dyslexia resulting in lifelong struggle to read and spell. Proper diagnosis is usually late and commonly achieved after structured schooling started, which causes delayed interventions. Legascreen set out to develop a preclinical screening to identify children at risk of developmental dyslexia.

The emergence of dyslexia in the developing brain.

Developmental dyslexia, a severe deficit in literacy learning, is a neurodevelopmental learning disorder. Yet, it is not clear whether existing neurobiological accounts of dyslexia capture potential predispositions of the deficit or consequences of reduced reading experience. Here, we longitudinally followed 32 children from preliterate to school age using functional and structural magnetic resonance imaging techniques.

No Evidence for Dystonia-Like Sensory Overflow of Tongue Representations in Adults Who Stutter.

Persistent developmental stuttering (PDS) disrupts speech fluency in about 1% of adults. Although many models of speech production assume an intact sensory feedback from the speech organs to the brain, very little is actually known about the integrity of their sensory representation in PDS. Here, we studied somatosensory evoked potentials (SEPs) in adults who stutter (AWS), with the aim of probing the integrity of sensory pathways.

Adults who stutter lack the specialised pre-speech facilitation found in non-stutterers.

Objectives: Persistent developmental stuttering is a speech fluency disorder defined by its symptoms, where the underlying neurophysiological causes remain uncertain. This study examined the underlying neurophysiological mechanisms of the speech planning process, using facilitation in the motor cortex during speech preparation as an analogue.

Methods: transcranial magnetic stimulation (TMS) pulses induced motor evoked potentials (MEPs), which were recorded from the tongue.

Functional Segregation of the Right Inferior Frontal Gyrus: Evidence From Coactivation-Based Parcellation.

Previous studies helped unraveling the functional architecture of the human cerebral cortex. However, a comprehensive functional segregation of right lateral prefrontal cortex is missing. Here, we delineated cortical clusters in right area 44 and 45 based on their task-constrained whole-brain activation patterns across neuroimaging experiments obtained from a large database.

and are putative modulators of dyslexia-related MMR.

Background: Dyslexia is a specific learning disorder affecting reading and spelling abilities. Its prevalence is ~5% in German-speaking individuals. Although the etiology of dyslexia largely remains to be determined, comprehensive evidence supports deficient phonological processing as a major contributing factor.

Shifted dynamic interactions between subcortical nuclei and inferior frontal gyri during response preparation in persistent developmental stuttering.

Persistent developmental stuttering is associated with basal ganglia dysfunction or dopamine dysregulation. Here, we studied whole-brain functional connectivity to test how basal ganglia structures coordinate and reorganize sensorimotor brain networks in stuttering. To this end, adults who stutter and fluent speakers (control participants) performed a response anticipation paradigm in the MRI scanner.

Altered morphology of the nucleus accumbens in persistent developmental stuttering.

Purpose: Neuroimaging studies in persistent developmental stuttering repeatedly report altered basal ganglia functions. Together with thalamus and cerebellum, these structures mediate sensorimotor functions and thus represent a plausible link between stuttering and neuroanatomy. However, stuttering is a complex, multifactorial disorder.

Dyslexia risk gene relates to representation of sound in the auditory brainstem.

Dyslexia is a reading disorder with strong associations with KIAA0319 and DCDC2. Both genes play a functional role in spike time precision of neurons. Strikingly, poor readers show an imprecise encoding of fast transients of speech in the auditory brainstem.

Auditory brainstem responses to stop consonants predict literacy.

Objective: Precise temporal coding of speech plays a pivotal role in sound processing throughout the central auditory system, which, in turn, influences literacy acquisition. The current study tests whether an electrophysiological measure of this precision predicts literacy skills.

Methods: Complex auditory brainstem responses were analysed from 62 native German-speaking children aged 11-13years.

Predicting early signs of dyslexia at a preliterate age by combining behavioral assessment with structural MRI.

Background: Recent studies suggest that neurobiological anomalies are already detectable in pre-school children with a family history of developmental dyslexia (DD). However, there is a lack of longitudinal studies showing a direct link between those differences at a preliterate age and the subsequent literacy difficulties seen in school. It is also not clear whether the prediction of DD in pre-school children can be significantly improved when considering neurobiological predictors, compared to models based on behavioral literacy precursors only.