## 1 Introduction  
Swallowing is a complex sensorimotor function involving volitional and reflexive activities to move saliva, liquids, and solid food from the oral cavity, through the pharynx and into the esophagus [1; 2; 3; 4]. Current knowledge of the neuro pathophysiology of the tongue during swallowing events is slowly advancing. This is partially related to the ever increasing knowledge regarding specific tongue activities and due to the discovery of five kinds of exteroceptors on the palate that connect to the nasopalatine nerve [5; 6]. In physiological conditions, the tongue during deglutition touches the palate behind the incisal papilla and its tip presses upon this point. This area is also called \"spot\" by myofunctional therapists and seems to act as a natural relay between the palate receptors and the cerebral cortex [7; 8]. It has been found that in patients suffering from dysfunctional swallowing, the tongue in resting conditions may be placed far from the palate, due to the prevalent activity of the geniglossus muscle, characteristic of a tongue often thrusting forward or between the dental arches [9; 10]. The geniglossus muscle is the largest in the tongue followed by the transverse, together representing almost 40% the tongue's mass ([PERSON] et al., 2018) [11]. Since both sets of muscles are involved in keeping the airways patent by displacing the tongue anteriorly (tongue thrust), the expectation is that they will cause different activations of cortical and subcortical areas than during swallow with tongue thrust than tongue against the palate. In clinical diagnosis, patients who do not keep the tip of the tongue on the \"spot\" during swallowing, frequently present postural abnormalities, and an incorrect distribution of the body weight [9]. The functional magnetic resonance imaging (fMRI) technique, has been used for over twenty years to investigate cortical representations during swallowing activities [12; 13; 14; 15; 16; 17; 18; 19]. Swallowing has been suggested to be multifocal [20; 21; 22; 23], being associated with the activation of insular regions of the cortex, the premotor/sensorimotor cortices and the anterior cingular gyrus [18; 24; 25; 26; 27]. Cortical activation has also been reported to be associated to volitional swallowing of saliva and water bolus [28; 29]. The most prominent swallow-related activation foci correspond to the lateral pericentral and perisylvian cortices, the anterior cingulate cortex (ACC) and adjacent supplementary motor area (SMA), the right insula, operculum, and precuneus. Moreover, the tongue elevation activates a larger total volume of cortex compared to swallowing activities with significantly greater activation within the ACC, SMA, right precentral and postcentral gyri, premotor cortex, right putamen, and the thalamus [30], caused by the stimulation of the palatal spot. In addition, a number of studies have reported lateralization of sensorimotor cortical activation [21; 22] whereas others have identified more bilateral activations [23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33], with handedness-independent hemispheric dominance [14; 22; 34]. We think our study complemented most of the other ones mentioned in this article, as each one offers a different view of something inherently complex such as the neuronal interplay between cognition and the sensory-motor behavior of the tongue, at least in two very specific movements. It has been documented for decades that there are two types of swallowing movements and that the one with tongue protrusion is not physiological because it is accomplished with a significant recruitment of other muscles. What was missing was a clear neurophysiological counterpart that this study aimed to solve by visualizing the additional recruitment of neurological areas, to confirm that a swallow with tongue protrusion is not efficient from a neuromuscular point of view.