Background: Swallowing is an important function for life sustenance but our understanding of its neural organization in the human cortex is not yet fully explored. Electroencephalography is a functional neuroimaging modality that already has and could further contribute to that direction. In this review, we have sought to gather and present findings from studies that used the EEG on healthy individuals for the investigation of the cortical mechanisms that moderate deglutition. Methods and Materials: Four databases were searched for studies that used the EEG as their main research modality on healthy individuals and administered various stimuli for them to swallow. The risk of bias assessment of the studies was conducted using the NIH rating scale for observational studies. Results: Our search yielded 393 studies in total and nine of them were included in the final discussion. The risk of bias assessment showed good quality of the studies. The nine studies were presented in a table following an adapted PICOS outline depicting the population, the comparisons, the means of measurement and the outcomes. Conclusions: Researchers studied the morphology of the signal before, during and after the swallow and its discrepancies in frequency in relation to stimuli alterations. Discrepancies in methodology and concordance with previous research are discussed.

Background: Transcranial Photobiomodulation (t-PBM) is a current, innovative method that is used in the therapy of many neurological and psychological diseases. Its mechanisms of action have been investigated and the most well described ways of action are its effects on mitochondrial function and on heat/light-activated ion channels on neurons membrane. It has been suggested that the increase in cerebral blood flow and the alterations of membrane ion channels are the most dominant potential mechanisms that cause the effects of PBM on quantitative electroencephalography (qEEG), that some recent studies have reported. Aim: The aim of this review is to describe the effects that t-PBM has on brain oscillations, as these are measured by qEEG. Methods: The research was carried out in the Pubmed database and it included all studies that had been published until February 2022. Results: Overall, sixty-eight studies were located and considered, searching with the terms Photobiomodulation or Light Therapy or Near Infrared Light and EEG. Only eleven of them used Photobiomodulation in order to observe the effect it can have on human brain oscillations, measured by qEEG. Two studies reported the EEG alterations after t-PBM application on the hand instead of the head. Thus, nine studies were included in the review, which applied t-PBM and observed the alterations that it brought upon qEEG of healthy adults or patients with memory problems. Conclusion: The studies showed that t-PBM increases high frequency neural activity and inhibits low frequency oscillations. The studies varied a lot in the ways of light application and the parameters of the light itself, as well as on their study population.