Functional Near-Infrared Spectroscopy (fNIRS) for Investigating Broca's Function & Lateralization
Sciences and Mathematics, College of
Psychological Science, Department of
BURS Faculty Advisor
Dr. Carole Scherling
Language hemispheric dominance associated with handedness is one of the most consistent findings in neuroscience (Knecht 2000). EEG and fMRI have tangibly demonstrated the presence of left hemispheric dominance in dextral individuals, and right hemispheric or bilateral dominance in sinistral individuals (Bidula 2017; Loring 1989). Such techniques have been valuable in discovery and surgery planning but have high-motion artifacts and accessibility challenges. The advancement of functional near-infrared spectroscopy (fNIRS) has provided a novel platform to non-invasively monitor and measure brain activity. Particularly, this method detects hemodynamic changes in oxygenated and deoxygenated hemoglobin (HbO and HbD, respectively) by emitting low levels of infrared light (Helmet 2013). Confirmatory studies must systematically investigate standard findings to demonstrate fNIRS' efficacy. Thirty-seven undergraduates (23 female; mean age (SD)= 20.3(1.7)); 31 dextral) completed the Edinburgh handedness survey and engaged in a verbal word-production task (bilateral Broca's area, 8x6 montage). Following Homer3 individual and group data processing, a laterality index was calculated to measure the level of HbO concentrations specifically in the left hemisphere. Results indicated a positive relationship between higher right-hand laterality and increased left hemispheric HbO concentrations during word production in comparison to left-hand dominant individuals, who showed less left hemispheric activity and more variable hemispheric activity (lesser hemispheric dominance). Study recruitment is ongoing to increase the size of the left-hand dominant participant pool, as well as additional probing of activity in the angular gyrus. A better understanding of fNIRS' ability to detect brain activity during different cognitive tasks is important in establishing this technique's diagnostic and research power for future studies. This is especially important considering this tool's high mobility, which increases accessibility for studies in groups outside of WEIRD cohorts.
Tadros, Youstina; Gowri Srinivasan, Prathyusha; Howard, Keirsten; Potts, Hannah; and Scherling, Carole PhD, "Functional Near-Infrared Spectroscopy (fNIRS) for Investigating Broca's Function & Lateralization" (2023). Belmont University Research Symposium (BURS). 306.