Reproducibility of swallow-induced cortical BOLD positive and negative fMRI activity

Abstract

Functional MRI (fMRI) studies have demonstrated that a number of brain regions (cingulate, insula, prefrontal, and sensory/motor cortices) display blood oxygen level-dependent (BOLD) positive activity during swallow. Negative BOLD activations and reproducibility of these activations have not been systematically studied. The aim of our study was to investigate the reproducibility of swallow-related cortical positive and negative BOLD activity across different fMRI sessions. We studied 16 healthy volunteers utilizing an fMRI event-related analysis. Individual analysis using a general linear model was used to remove undesirable signal changes correlated with motion, white matter, and cerebrospinal fluid. The group analysis used a mixed-effects multilevel model to identify active cortical regions. The volume and magnitude of a BOLD signal within each cluster was compared between the two study sessions. All subjects showed significant clustered BOLD activity within the known areas of cortical swallowing network across both sessions. The cross-correlation coefficient of percent fMRI signal change and the number of activated voxels across both positive and negative BOLD networks were similar between the two studies (r ≥ 0.87, P < 0.0001). Swallow-associated negative BOLD activity was comparable to the well-defined "default-mode" network, and positive BOLD activity had noticeable overlap with the previously described "task-positive" network. Swallow activates two parallel cortical networks. These include a positive and a negative BOLD network, respectively, correlated and anticorrelated with swallow stimulus. Group cortical activity maps, as well as extent and amplitude of activity induced by volitional swallowing in the cortical swallowing network, are reproducible between study sessions.

Functional connectivity of the cortical swallowing network in humans

“…Functional EPI scans were acquired over 34 contiguous 4-mm thick sagittal slices over the whole brain volume in an interleaved fashion without any gap or overlap, with a slice-wise pixel resolution of 64 × 64 pixels over a 240 mm field of view yielding a within-slice resolution of 3.75 × 3.75 mm, captured with an echo time (TE) of 23.4 ms and a repetition time (TR) of 2000 ms.At the end of the second scan session, a separate paradigm driven functional scan was performed, which was strictly used to independently identify cortical and subcortical areas activated with swallowing in order to use them as seed regions for FC analysis ( functionally guided connectivity analysis ). Details of the imaging parameters and analytical techniques of this “seed finder” scan have been previously described (Babaei et al, 2012). …”

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.…”

“…Guidance provided to different groups of surveyed subjects included visual (3,7,8,10,14,(16)(17)(18)(19)(23)(24)(25)(26)(27)(28)(30)(31)(32) , hearing (6,16,21,29) and sensorial clues (5,9,11,13,15,17,19,24,29) . In studies examining the food swallowing, its ingestion was the track for the patient to swallow, i.e., the absence of formal statement was a major factor, differentiating it from studies with other types of tasks.…”

Emergence of Deglutology: A Transdisciplinary Field

“…Although a consistent ensemble of brain regions (sensorimotor, cingulate and insular cortices, lateral prefrontal and parietal regions) has been identified in governance of deglutition 51, 52 , the specific role of distinct brain regions and their interactions await further study. Functional connectivity of swallowing network and interactions of involved brain regions has just been recently described for resting state and during swallowing 53-55 .…”