Neural activation of swallowing and swallowing‐related tasks in healthy young adults: An attempt to separate the components of deglutition

Abstract

Understanding the underlying neural pathways that govern the highly complex neuromuscular action of swallowing is considered crucial in the process of correctly identifying and treating swallowing disorders. The aim of the present investigation was to identify the neural activations of the different components of deglutition in healthy young adults using functional magnetic resonance imaging (fMRI). Ten right-handed young healthy individuals were scanned in a 3-Tesla Siemens Allegra MRI scanner. Participants were visually cued for both a "Swallow" task and for component/control tasks ("Prepare to swallow", "Tap your tongue", and "Clear your throat") in a randomized order (event-related design). Behavioral interleaved gradient (BIG) methodology was used to address movement-related artifacts. Areas activated during each of the three component tasks enabled a partial differentiation of the neural localization for various components of the swallow. Areas that were more activated during throat clearing than other components included the posterior insula and small portions of the post- and pre-central gyri bilaterally. Tongue tapping showed higher activation in portions of the primary sensorimotor and premotor cortices and the parietal lobules. Planning did not show any areas that were more activated than in the other component tasks. When swallowing was compared with all other tasks, there was significantly more activation in the cerebellum, thalamus, cingulate gyrus, and all areas of the primary sensorimotor cortex bilaterally.

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.…”

“…In an attempt to assess the representativeness of sensory--motor organs, the authors proposed an examination of cortical responses to movements used in rehabilitation procedures, such as orofacial exercises (1,14,21,27) and maneuvers used in rehabilitation (18) . Even on population with dysphagia, they used swallowing of different types of food, such as water (5,(29)(30)(31) , barium (5,29,31) and saliva (5,(29)(30)(31)(32) .…”

“…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.…”

“…It is assumed that swallowing without food intake, i.e., saliva only, when lying down, occurs in people's various everyday situations, either asleep, or awake. However, the authors agree that it is doubtful that the neural swallowing activation would vary according to body positioning (3,14,33) . Other factors that may influence the signal accuracy include the use of medication and its effects on the hemodynamic response of neural excitability, the motion artifacts required for certain motor tasks in assessment and the patient's degree of relaxation (5) .…”