Cortical activation during human volitional swallowing: an event-related fMRI study.
ABSTRACT Functional magnetic resonance imaging (fMRI) provides a safe, noninvasive method for studying task-related cortical neuronal activity. Because the cerebral cortex is strongly implicated in the control of human swallowing, we sought to identify its functional neuroanatomy using fMRI. In 10 healthy volunteers, a swallow event-related paradigm was performed by injecting 5 ml water bolus into the oral cavity every 30 s. Whole brain functional magnetic susceptibility -weighted spiral imaging data were simultaneously acquired over 600 s on a 1.5-T magnetic resonance scanner, utilizing the blood oxygenation level-dependent technique, and correlation maps were generated using both >99% percentile rank and spatial extent thresholding. We observed areas of increased signal change consistently in caudal sensorimotor cortex, anterior insula, premotor cortex, frontal operculum, anterior cingulate and prefrontal cortex, anterolateral and posterior parietal cortex, and precuneus and superiomedial temporal cortex. Less consistent activations were also seen in posterior cingulate cortex and putamen and caudate nuclei. Activations were bilateral, but almost every region, particularly the premotor, insular, and frontal opercular cortices, displayed lateralization to one or the other hemisphere. Swallow-related cortical activity is multidimensional, recruiting brain areas implicated in processing motor, sensory, and attention/affective aspects of the task.
Article: Task-dependent differences in corticobulbar excitability of the submental motor projections: Implications for neural control of swallowing.[show abstract] [hide abstract]
ABSTRACT: It has been suggested that the primary motor cortex plays a substantial role in the neural circuitry that controls swallowing. Although its role in the voluntary oral phase of swallowing is undisputed, its precise role in motor control of the more reflexive, pharyngeal phase of swallowing is unclear. The contribution of the primary motor cortex to the pharyngeal phase of swallowing was examined using transcranial magnetic stimulation (TMS) to evoke motor evoked potentials (MEPs) in the anterior hyomandibular muscle group during either volitional submental muscle contraction or contraction during the pharyngeal phase of both volitionally, and reflexively, initiated swallowing. For each subject, in all three conditions, TMS was triggered when submental surface EMG (sEMG) reached 75% of the mean maximal submental sEMG amplitude measured during 10 volitional swallows. MEPs recorded during volitional submental muscle contraction were elicited in 22 of the 35 healthy subjects examined (63%). Only 16 of these 22 subjects (45.7%) also displayed MEPs recorded during volitional swallowing, but their MEP amplitudes were larger when triggered by submental muscle contraction than when triggered by volitional swallowing. Additionally, only 7 subjects (of 19 tested) showed MEPs triggered by submental muscle contraction during a reflexively triggered pharyngeal swallow. These differences indicate differing levels of net M1 excitability during execution of the investigated tasks, possibly brought about by task-dependent changes in the balance of excitatory and inhibitory neural activity.Brain research bulletin 01/2011; 84(1):88-93. · 2.18 Impact Factor
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ABSTRACT: Dysphagia is a major complication in hemispheric as well as brainstem stroke patients causing aspiration pneumonia and increased mortality. Little is known about the recovery from dysphagia after stroke. The aim of the present study was to determine the different patterns of cortical swallowing processing in patients with hemispheric and brainstem stroke with and without dysphagia in the early subacute phase. We measured brain activity by mean of whole-head MEG in 37 patients with different stroke localisation 8.2+/-4.8 days after stroke to study changes in cortical activation during self-paced swallowing. An age matched group of healthy subjects served as controls. Data were analyzed by means of synthetic aperture magnetometry and group analyses were performed using a permutation test. Our results demonstrate strong bilateral reduction of cortical swallowing activation in dysphagic patients with hemispheric stroke. In hemispheric stroke without dysphagia, bilateral activation was found. In the small group of patients with brainstem stroke we observed a reduction of cortical activation and a right hemispheric lateralization. Bulbar central pattern generators coordinate the pharyngeal swallowing phase. The observed right hemispheric lateralization in brainstem stroke can therefore be interpreted as acute cortical compensation of subcortically caused dysphagia. The reduction of activation in brainstem stroke patients and dysphagic patients with cortical stroke could be explained in terms of diaschisis.BMC Neurology 03/2011; 11:34. · 2.17 Impact Factor
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ABSTRACT: Cerebral palsy (CP) is the most common physical disability in early childhood. The worldwide prevalence of CP is approximately 2-2.5 per 1,000 live births. It has been clinically defined as a group of motor, cognitive, and perceptive impairments secondary to a non-progressive defect or lesion of the developing brain. Children with CP can have swallowing problems with severe drooling as one of the consequences. Malnutrition and recurrent aspiration pneumonia can increase the risk of morbidity and mortality. Early attention should be given to dysphagia and excessive drooling and their substantial contribution to the burden of a child with CP and his/her family. This review displays the important functional and anatomical issues related to swallowing problems in children with CP based on relevant literature and expert opinion. Furthermore, based on our experience, we describe a plan for approach of investigation and treatment of swallowing problems in cerebral palsy.European Journal of Pediatrics 09/2011; 171(3):409-14. · 1.88 Impact Factor