Task-Dependent Neural Activity in the Posterior Parietal Cortex Is Associated with Better Balance in Adults with Acquired Brain Injury

<b>Background/Objectives</b>: There is scarce evidence on the neural underpinnings of balance in people with chronic acquired brain injury (ABI). Thus, the objective was to measure this in adults with ABI during four balance tasks and to examine the relationship between neural activity and balance performance. <b>Methods</b>: Twenty-seven adults with chronic ABI (Age (M ± SD): 51.30 ± 18.67 years, 18 females) were included in this study. Functional near-infrared spectroscopy (fNIRS) was used to measure task-dependent neural activity, which was quantified using oxygenated hemoglobin (HbO) beta values. A force plate was used to measure balance performance, quantified as the amount of sway. One-sample t-tests were used to test for significant task-dependent neural activity during each balance task (HbO > 0) at each fNIRS channel. Pearson's correlations were used to test for relationships between fNIRS channels with significant task-dependent activity and balance performance. <b>Results</b>: Significant task-dependent neural activity was observed in an fNIRS channel situated over the right superior parietal lobe, <i>p</i> = 0.039, along with 4 channels over the right inferior parietal lobe (IPL), <i>p</i> range = 0.013-0.043 and 3 channels over left IPL, <i>p</i> range = 0.019-0.030. There were moderate negative relationships between IPL activity and balance, r range = -0.441-0.419, <i>p</i> range = 0.031-0.046. <b>Conclusions</b>: We observed significant task-dependent neural activity in superior and inferior parietal lobes. Additionally, greater neural recruitment of the inferior parietal lobes was associated with less sway during balance performance, which provides evidence of the neural underpinnings of balance in ABI.