High-density multidistance fNIRS enhances detection of brain activity during a word-color Stroop task.

Significance: Functional near-infrared spectroscopy (fNIRS) enables neuroimaging in scenarios where other modalities are less suitable, such as during motion tasks or in low-resource environments. Sparse fNIRS arrays with 30 mm channel spacing are widely used but have limited spatial resolution. High-density (HD) arrays with overlapping, multidistance channels improve sensitivity and localization but increase costs and setup times. A statistical comparison of HD and sparse arrays is needed for evaluating the benefits and trade-offs of HD arrays. Aim: This study provides a statistical comparison of HD and sparse fNIRS performance to inform array selection in future research. Approach: We measured prefrontal cortex (PFC) activation during congruent and incongruent word-color Stroop (WCS) tasks using both sparse and HD arrays for 17 healthy adult participants, comparing dorsolateral PFC channel and image results at the group level. Results: Although both arrays detected activation in channel space during incongruent WCS, channel and image space results demonstrated superior localization and sensitivity with the HD array for all WCS. Conclusion: Sparse channel data may suitably detect activation from cognitively demanding tasks, such as incongruent WCS. However, the HD array outperformed sparse in detecting and localizing brain activity in image space, particularly during lower cognitive load tasks, making it more suitable for neuroimaging applications.