Functional near-infrared spectroscopy (fNIRS) brain imaging of multi-sensory integration during computerized dynamic posturography in middle-aged and older adults

Abstract

Studies suggest that aging affects the sensory re-weighting process, but the neuroimaging evidence is minimal. Functional Near-Infrared Spectroscopy (fNIRS) is a novel neuroimaging tool that can detect brain activities during dynamic movement condition. In this study, fNIRS was used to investigate the hemodynamic changes in the frontal-lateral, temporal-parietal, and occipital regions of interest (ROIs) during four sensory integration conditions that manipulated visual and somatosensory feedback in 15 middle-aged and 15 older adults. The results showed that the temporal-parietal ROI was activated more when somatosensory and visual information were absent in both groups, which indicated the sole use of vestibular input for maintaining balance. While both older adults and middle-aged adults had greater activity in most brain ROIs during changes in the sensory conditions, the older adults had greater increases in the occipital ROI and frontal-lateral ROIs. These findings suggest a cortical component to sensory re-weighting that is more distributed and requires greater attention in older adults.

Keywords: Aging; Functional near-infrared spectroscopy (fNIRS); Sensory re-weighting.

Figures

Fig. 1

Probe setting

Fig. 2

a, b Estimated regression coefficients, β, of changes in Oxy-Hemoglobin ( HbO2) from baseline conditions to test conditions in Older and Middle-age adults for Trial 1 (top) and Trial 2 (bottom). Regions of Interest Occipital (Occ), Right Fronto-lateral (R. F-L.), Right Temporo-Parietal (R. T-P), Left Fronto-lateral (L. F-L), and Left Temporo-Parietal (L. T-P). *Significant difference between task and baseline, pFDR < 0.05. #Significant difference between Older and Middle-age adults, pFDR < 0.05. c, d Estimated regression coefficients, β, of changes in Oxy-Hemoglobin ( HbO2) from baseline conditions to test conditions in Older and Middle-age adults for Trial 3 (top) and Trial 4 (bottom). Regions of Interest Occipital (Occ), Right Fronto-lateral (R. F-L.), Right Temporo-Parietal (R. T-P), Left Fronto-lateral (L. F-L), and Left Temporo-Parietal (L. T-P). *Significant difference between task and baseline, pFDR < 0.05. #Significant difference between Older and Middle-age adults, pFDR < 0.05

Fig. 3

a–d T-score maps of fNIRS oxyhemoglobin changes from baseline to test conditions for individual channels during the four different sensory integration trials in Middle-Aged (a, c, e, g) and Older (b, d, f, h) adults. Channels that were significantly activated (pFDR < 0.05) are shown as thick lines overlying brain. e, h T-score maps of fNIRS oxyhemoglobin changes from baseline to test conditions for individual channels during the four different sensory integration trials in Middle-aged (a, c, e, g) and Older (b, d, f, h) adults. Channels that were significantly activated (pFDR < 0.05) are shown as thick lines overlying brain

Fig. 3

a–d T-score maps of fNIRS oxyhemoglobin changes from baseline to test conditions for individual channels during the four different sensory integration trials in Middle-Aged (a, c, e, g) and Older (b, d, f, h) adults. Channels that were significantly activated (pFDR < 0.05) are shown as thick lines overlying brain. e, h T-score maps of fNIRS oxyhemoglobin changes from baseline to test conditions for individual channels during the four different sensory integration trials in Middle-aged (a, c, e, g) and Older (b, d, f, h) adults. Channels that were significantly activated (pFDR < 0.05) are shown as thick lines overlying brain

Fig. 4

RMS COP in four different sensory integration trials in Middle-age (a) and Older (b) adults