Publications by Year: 2015

2015
Alcohol responsiveness in laryngeal dystonia: a survey study
Diana N Kirke, Steven J Frucht, and Kristina Simonyan. 2015. “Alcohol responsiveness in laryngeal dystonia: a survey study.” J Neurol, 262, 6, Pp. 1548-56.Abstract
Laryngeal dystonia (LD) is a task-specific focal dystonia of unknown pathophysiology affecting speech production. We examined the demographics of anecdotally reported alcohol use and its effects on LD symptoms using an online survey based on Research Electronic Data Capture (REDCap™) and National Spasmodic Dysphonia Association's patient registry. From 641 participants, 531 were selected for data analysis, and 110 were excluded because of unconfirmed diagnosis. A total of 406 patients (76.5 %) had LD and 125 (23.5 %) had LD and voice tremor (LD/VT). The consumption of alcohol was reported by 374 LD (92.1 %) and 109 LD/VT (87.2 %) patients. Improvement of voice symptoms after alcohol ingestion was noted by 227 LD (55.9 % of all patients) and 73 LD/VT (58.4 %), which paralleled the improvement observed by patient's family and/or friends in 214 LD (57.2 %) and 69 LD/VT (63.3 %) patients. The benefits lasted 1-3 h in both groups with the maximum effect after 2 drinks in LD patients (p = 0.002), whereas LD/VT symptoms improved independent of the consumed amount (p = 0.48). Our data suggest that isolated dystonic symptoms, such as in LD, are responsive to alcohol intake and this responsiveness is not attributed to the presence of VT, which is known to have significant benefits from alcohol ingestion. Alcohol may modulate the pathophysiological mechanisms underlying abnormal neurotransmission of γ-aminobutyric acid (GABA) in dystonia and as such provide new avenues for novel therapeutic options in these patients.
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The Functional Connectome of Speech Control
Stefan Fuertinger, Barry Horwitz, and Kristina Simonyan. 2015. “The Functional Connectome of Speech Control.” PLoS Biol, 13, 7, Pp. e1002209.Abstract
In the past few years, several studies have been directed to understanding the complexity of functional interactions between different brain regions during various human behaviors. Among these, neuroimaging research installed the notion that speech and language require an orchestration of brain regions for comprehension, planning, and integration of a heard sound with a spoken word. However, these studies have been largely limited to mapping the neural correlates of separate speech elements and examining distinct cortical or subcortical circuits involved in different aspects of speech control. As a result, the complexity of the brain network machinery controlling speech and language remained largely unknown. Using graph theoretical analysis of functional MRI (fMRI) data in healthy subjects, we quantified the large-scale speech network topology by constructing functional brain networks of increasing hierarchy from the resting state to motor output of meaningless syllables to complex production of real-life speech as well as compared to non-speech-related sequential finger tapping and pure tone discrimination networks. We identified a segregated network of highly connected local neural communities (hubs) in the primary sensorimotor and parietal regions, which formed a commonly shared core hub network across the examined conditions, with the left area 4p playing an important role in speech network organization. These sensorimotor core hubs exhibited features of flexible hubs based on their participation in several functional domains across different networks and ability to adaptively switch long-range functional connectivity depending on task content, resulting in a distinct community structure of each examined network. Specifically, compared to other tasks, speech production was characterized by the formation of six distinct neural communities with specialized recruitment of the prefrontal cortex, insula, putamen, and thalamus, which collectively forged the formation of the functional speech connectome. In addition, the observed capacity of the primary sensorimotor cortex to exhibit operational heterogeneity challenged the established concept of unimodality of this region.
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Negative dystonia of the palate: a novel entity and diagnostic consideration in hypernasal speech
Catherine F Sinclair, Kristina Simonyan, Mitchell F Brin, and Andrew Blitzer. 2015. “Negative dystonia of the palate: a novel entity and diagnostic consideration in hypernasal speech.” Laryngoscope, 125, 6, Pp. 1426-32.Abstract
OBJECTIVE: To present the first documented series of patients with negative dystonia (ND) of the palate, including clinical symptoms, functional MRI findings, and management options. STUDY DESIGN: Case series ascertained from clinical research centers that evaluated patients with both hyperkinetic and hypokinetic movement disorders. METHODS: Between July 1983 and March 2013, data was collected on patient demographics, disease characteristics, functional MRI findings, long-term management options, and outcomes. We sought patients whose clinical examination demonstrated absent palatal movement on speaking, despite normal palatal activity on other activities. RESULTS: Five patients (2 males, 3 females) met clinical criteria. All patients presented with hypernasal speech without associated dysphagia. Clinical examination revealed absent palatal movement on speaking despite intact gag reflexes, normal palate elevation on swallowing, and normal cranial nerve examinations. Other cranial and/or limb dystonias were present in four patients (80.0%). Three patients (60.0%) had previously failed oral pharmacologic therapy. Two patients underwent functional magnetic resonance imaging (fMRI) studies, which demonstrated an overall decrease of cortical and subcortical activation during production of symptomatic syllables and asymptomatic coughing. Management included speech therapy (all patients) and palatal lift (2 patients) with limited improvement. Calcium hydroxyapatite injection (1 patient) into the soft palate and Passavants' ridge was beneficial. CONCLUSIONS: This is the first report of ND of the palate. Characteristic findings were task-specific absent palatal movement with speech, despite normal movement on swallowing, coughing, and an intact gag reflex, as well as disorder-specific decreased brain activation on functional MRI. A diagnosis of ND of the palate should be considered for patients who present with hypernasal speech. LEVEL OF EVIDENCE: 4.
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Speech networks at rest and in action: interactions between functional brain networks controlling speech production
Kristina Simonyan and Stefan Fuertinger. 2015. “Speech networks at rest and in action: interactions between functional brain networks controlling speech production.” J Neurophysiol, 113, 7, Pp. 2967-78.Abstract
Speech production is one of the most complex human behaviors. Although brain activation during speaking has been well investigated, our understanding of interactions between the brain regions and neural networks remains scarce. We combined seed-based interregional correlation analysis with graph theoretical analysis of functional MRI data during the resting state and sentence production in healthy subjects to investigate the interface and topology of functional networks originating from the key brain regions controlling speech, i.e., the laryngeal/orofacial motor cortex, inferior frontal and superior temporal gyri, supplementary motor area, cingulate cortex, putamen, and thalamus. During both resting and speaking, the interactions between these networks were bilaterally distributed and centered on the sensorimotor brain regions. However, speech production preferentially recruited the inferior parietal lobule (IPL) and cerebellum into the large-scale network, suggesting the importance of these regions in facilitation of the transition from the resting state to speaking. Furthermore, the cerebellum (lobule VI) was the most prominent region showing functional influences on speech-network integration and segregation. Although networks were bilaterally distributed, interregional connectivity during speaking was stronger in the left vs. right hemisphere, which may have underlined a more homogeneous overlap between the examined networks in the left hemisphere. Among these, the laryngeal motor cortex (LMC) established a core network that fully overlapped with all other speech-related networks, determining the extent of network interactions. Our data demonstrate complex interactions of large-scale brain networks controlling speech production and point to the critical role of the LMC, IPL, and cerebellum in the formation of speech production network.
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