Test-retest reliability of functional near-infrared spectroscopy during a finger-tapping and postural task in healthy older adults

SIGNIFICANCE: Functional near-infrared spectroscopy (fNIRS) is increasingly employed in studies requiring repeated measurements, yet test-retest reliability is largely unknown. AIM: To investigate test-retest reliability during a postural and a finger-tapping task with and without cap-removal. APPROACH: Twenty healthy older adults performed a postural and a finger-tapping task. The tasks were repeated twice in one session and once the next day. A portable fNIRS system measured cortical hemodynamics ([Formula: see text]) in five regions of interest for the postural task and in the hand motor region for finger-tapping. RESULTS: Test-retest reliability without cap-removal was excellent for the prefrontal cortex (PFC), the premotor cortex (PMC) and the somatosensory cortex (SSC) (intraclass correlation coefficient [Formula: see text]), and fair for the frontal eye fields (FEF) and the supplementary motor area (SMA) ([Formula: see text]). After cap-removal, reliability reduced for PFC and SSC ([Formula: see text]), became poor for SMA ([Formula: see text]) and PMC ([Formula: see text]) and remained good for FEF ([Formula: see text]). Similarly, good reliability ([Formula: see text]) was apparent for the hand motor region without cap-removal, which deteriorated after cap-removal ([Formula: see text]). CONCLUSIONS: Test-retest reliability of fNIRS measurements during two separate motor tasks in healthy older adults was fair to excellent when the cap remained in place. However, removing the fNIRS cap between measurements compromised reliability.