Elsevier

Neuroscience

Volume 153, Issue 4, 2 June 2008, Pages 1300-1308
Neuroscience

Sensory system
Functional MRI of oropharyngeal air-pulse stimulation

https://doi.org/10.1016/j.neuroscience.2008.02.079Get rights and content

Abstract

Although the posterior oral cavity and oropharynx play a major role in swallowing, their central representation is poorly understood. High-field functional magnetic resonance imaging of the brain was used to study the central processing of brief air-pulses, delivered to the peritonsillar region of the lateral oropharynx, in six healthy adults. Bilateral air-pulse stimulation was associated with the activation of a bilateral network including the primary somatosensory cortex and the thalamus, classic motor areas (primary motor cortex, supplementary motor area, cingulate motor areas), and polymodal areas (including the insula and frontal cortex). These results suggest that oropharyngeal stimulation can activate a bilaterally distributed cortical network that overlaps cortical regions previously implicated in oral and pharyngeal sensorimotor functions such as tongue movement, mastication, and swallowing. The present study also demonstrates the utility of air-pulse stimulation in investigating oropharyngeal sensorimotor processing in functional brain imaging experiments.

Section snippets

Participants

Six right-handed female volunteers with no history of swallowing, orofacial, gastrointestinal, respiratory, or neurological problems participated in the study (mean age: 27 years, age range: 21–45 years). All subjects were non-smokers, and were not taking any medications that may have affected their oropharyngeal function. The sample was composed exclusively of females for two reasons. First, our previous functional magnetic resonance imaging (fMRI) experience has suggested that fMRI data from

Results

Brain activation associated with air-pulse stimulation was characterized by a considerable intra- and interindividual variability in all three stimulation conditions (left-sided, right-sided, and bilateral stimulation). Activation strength (as represented by the Z value of the test statistics) and location of the maximum activation varied within individuals when comparing the left and right hemisphere and across individuals. Fig. 4 illustrates the variability of sensorimotor activation

Discussion

The present fMRI study suggests that air-pulse trains delivered to the oropharynx activate a widely distributed network of cortical and subcortical areas. This network includes core areas of the somatosensory system, including the thalamus and the primary somatosensory cortex (SI). In addition, classical motor areas (primary motor cortex (MI), supplementary motor area (SMA), cingulate motor areas) and polymodal areas (such as the insula and frontal cortex) were activated in association with

Acknowledgments

This research was supported by a grant from the Heart and Stroke Foundation of Ontario (R. E. Martin), Ontario Ministry of Health and Long-Term Care Salary Support (R. E. Martin), Premier's Research Excellence Award (R. E. Martin), Canada Research Chair Support (R. S. Menon), and Canadian Institutes of Health Research Maintenance Grant (R. S. Menon).

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