# Automating Stimulation Frequency Selection for SSVEP-Based Brain-Computer Interfaces
## 7 Conclusions  
Brain-computer interfaces are rapidly gaining popularity due to their potentially wide range of applications, being equally beneficial for both healthy individuals and patients suffering from severe illnesses. The vast number of approaches, relying on various neurophysiological mechanisms and methods of acquisition and processing, provides an opportunity to actively pursue multiple directions in search of optimal solutions. One such approach that has demonstrated practical effectiveness involves the development of BCIs based on steady-state visually evoked potential. Currently used stimulation protocols typically focus on frequencies exceeding 30 Hz, which is attributed to lower fatigue likelihood in individuals as well as reduced probability of epileptic activity when displaying rhythmically flickering stimuli. However, within the scope of this current research, we focused on a frequency range from 5 to 25 Hz. The use of photoflashes at these frequencies yields a maximum SSVEP amplitude compared to frequencies above 30 Hz [13]. By limiting ourselves to frequencies within this range, our objective was to develop an algorithm for identifying the most optimal stimulation frequencies for each subject while considering their subjective level of stress/discomfort (being quantified by using the theta-to-beta power ratio) when presented with stimuli at specific frequencies. The improvement of approaches in developing increasingly reliable, accurate, and user-friendly brain-computer interfaces enables the active integration of these technologies into clinical practice, significantly enhancing the quality of life for patients. Over the decades of BCI utilization, including those based on SSVEP, substantial advancements have been achieved in rehabilitating patients who have suffered from strokes [56; 57], as well as patients recovering from severe spinal [58] or brain injuries [59; 60]. Personalization of diagnostic programs and therapeutic interventions in modern medicine is one of the main directions of development. The development of next-generation interfaces that take into account a greater number of influencing factors, considering the individual condition of the patient during BCI training, will potentially provide patients with the ability to actively interact with the external world and lead lifestyles that are qualitatively indistinguishable from those of healthy individuals. Despite being conducted on a sample of healthy subjects, our study nevertheless has the feasibility and potential to be used on patients who are experiencing significant difficulties in returning to their normal lives after a previous illness. Future plans include performing the experiment described in this article on a larger group of participants, using the obtained individual stimulation frequencies in real conditions, and analyzing the variability of optimal frequencies calculated for participants over time. We also plan to quantitatively evaluate the reasonability of this approach relative to other methods for selecting individual photostimuli frequencies and the scenario without any selection at all. Conceptualization, A.K., A.G., M.B., A.P. and O.R. ; methodology, A.K. and A.G.; software, A.K. ; validation, A.K., A.G. and M.B. ; formal analysis, A.K., A.G. and A.P. ; investigation, A.K. and A.G.; resources, A.K. ; data curation, A.K. ; writing--original draft preparation, A.K., A.G., M.B. and A.P. ; writing--review and editing, O.R. ; visualization, A.K. ; supervision, O.R. ; project administration, M.B. ; funding acquisition, M.B. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Faculty of Humanities of Novosibirsk State Technical University (protocol code 01_02_2023). The data presented in this study are available upon request from the corresponding author.