fNIRS as an Emotional Assessment Tool in the Prefrontal Cortex of Women

Abstract

Introduction: The study of emotions using neuroimaging techniques such as functional near-infrared spectroscopy (fNIRS) is gaining momentum as a promising approach to understanding the brain and mind. Objective: To evaluate prefrontal cortex activation in women observing standardized emotional images (International Affective Picture System [IAPS]) across three categories: neutral, violent, and landscapes. Method: Using a quasi-experimental design, 52 right-handed women aged 18 to 45 years participated. Brain activity was recorded using an 8-channel fNIRS system with two photodetectors placed over the prefrontal cortex. Signal processing included channel validation using the scalp coupling index, high-pass and low-pass filtering, and spline and wavelet filtering for artifact removal, followed by descriptive analysis, repeated-measures ANOVA, and linear mixed-effects modeling. Results: A significant increase in oxygenated hemoglobin (HbO) was observed in channels 1, 5, and 8, mainly in the left hemisphere, during exposure to violent images, whereas neutral and landscape images elicited lower activation. Deoxygenated hemoglobin (HbR) patterns were less consistent, showing some differences in the right hemisphere. No strong hemispheric lateralization was found, although a slight trend toward left-hemisphere dominance emerged. Conclusion: Violent images significantly activate the prefrontal cortex, particularly in the left hemisphere. fNIRS proves effective for studying emotional responses in ecologically valid settings. However, results suggest that both stimulus type and exposure duration are critical factors in emotional neuroimaging studies.