The role of fNIRS in assessing motor function: A bibliometric review on extremity applications

Understanding the mechanisms that control motor movements in the brain is crucial to understand neurological disorders and brain plasticity. Functional near-infrared spectroscopy (fNIRS) is an increasingly popular noninvasive method for investigating these processes. This study examined the application of fNIRS in the field of motor function and limbs and showed that after a limited development period between 2006 and 2010, it has grown rapidly since 2010. The number of publications and citations peaked in 2021 to 2022, with a significant increase in citations in 2023 to 2024. Co-citation analysis revealed 26,950 citations in 982 publications, indicating that these studies made a significant contribution to the scientific literature. Over the last 18 years, 2962 authors from 55 countries have published 982 articles on fNIRS, with an average annual growth of 31.75% in publications and 42.55% in citations since 2010. Furthermore, the analysis of combined fNIRS-electroencephalography studies showed that methodological advances are the main focus of research in the field. Further studies that combine the power of combined neuroimaging methods to monitor both electrical activity (electroencephalography) and hemodynamic changes (fNIRS) are expected. In addition to motor and limb research and brain function studies, studies on these approaches in treating diseases such as Parkinson disease and chronic stroke are also drawing attention, showing the growing importance of fNIRS in motor and limb research, and that it will be an important data tool for future studies.