Functional connectivity and laterality of the motor and sensory components in the volitional swallowing network

Abstract

Functional neuroimaging has shown that multiple brain regions are active during volitional swallowing. Little is known, however, about which regions integrate motor execution and sensory feedback in the swallowing system. Although unilateral brain lesions in either hemisphere can produce swallowing deficits, some functional neuroimaging studies indicate that the left hemisphere has greater activation in certain sensory and motor-related swallowing regions. In this study, correlation coefficients were computed for five seed regions during volitional saliva swallowing to determine the functional relationships of these regions with the rest of the brain: the anterior and posterior insula, inferior frontal gyrus (BA44), primary sensory cortex (S1), and primary motor cortex (M1). A laterality index (LI) was derived that accounts for relative differences in total, positive connected voxels for the left/right hemisphere seeds. Clusters of significantly connected voxels were greater from the anterior and posterior insula than from the other three seed regions. Interactions of the insula with other brain regions were greater on the left than on the right during volitional swallowing. Group means showed laterality in the anterior insula (LI = 0.25) and the posterior insula (LI = 0.33). BA44 showed a lesser degree of difference in left versus right hemisphere interactions (LI = 0.12) while S1 did not show lateralization (LI = 0.02) and M1 showed some predominance of interactions in the right hemisphere (LI = −0.19). The greater connectivity from the left hemisphere insula to brain regions within and across hemispheres suggests that the insula is a primary integrative region for volitional swallowing in humans.

Dysphagia after pediatric functional hemispherectomy

“…15,18 In light of this variability, there may be a role for functional imaging assessment of the swallow prior to hemispherectomy as a mechanism to clarify postoperative dysphagia risk. This may be especially relevant in children with preoperative dysphagia for whom the risk of permanent deficit is present.…”

Ressonância magnética funcional e deglutição: revisão sistemática

“…Scientific articles were categorized specific features to the swallowing cortical representation (3,(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) . Research on elderly and patients with dysphagia underwent compared to control groups.…”

“…A chronological analysis of the presented studies, observed that initially the concern was the confirmation of cortical activation mechanisms for swallowing Therefore, procedures such as saliva (1,3,5,7,(16)(17)(18)(19)(20)22,23,26,(29)(30)(31)(32) , water (5,11,12,17,(24)(25)(26)28,29,31) , barium (5,26,29,31) swallowing were performed, comparing swallow and not swallow (1,7,14,27) . Later on, studies began to analyze differences in the cortical areas, responsible for each motor phase, differentiating the role of the structures involved.…”

fMRI and MRS measures of neuroplasticity in the pharyngeal motor cortex

“…Among the several brain areas involved in this swallowing network, the insula was shown to have a central integrative role in regulating this essential function. Connectivity studies showed that voxel clusters were larger from the insula than other seed regions (Lowell et al, 2012) or was functionally connected to prefrontal operculum regions (Babaei et al, 2013). Moreover, an activation likelihood estimation meta-analysis of imaging studies on swallowing showed that saliva swallowing involves a larger involvement of premotor areas when compared to water swallowing, whilst water swallowing is associated with activation in the right inferior parietal region.…”