Sensory manipulation results in increased dorsolateral prefrontal cortex activation during static postural balance in sedentary older adults: An fNIRS study.

Wei‐Peng Teo,Alicia M Goodwill,Makii Muthalib,Helen Macpherson,Ashlee M Hendy

doi:10.1002/brb3.1109

Wei‐Peng Teo, Alicia M Goodwill + Show 3 more

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https://doi.org/10.1002/brb3.1109

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Abstract

BackgroundThe dorsolateral prefrontal cortex (DLPFC) is involved with allocating attentional resources to maintain postural control. However, it is unknown whether age‐related structural and functional declines of the DLPFC may impair postural control during sensory manipulation. In this study, we aim to understand the effects of aging on the DLPFC when sensory cues were removed or presented inaccurately (i.e., increased sensory complexity) during the sensory orientation test (SOT).MethodsTwenty young (18–25 years) and 18 older (66–73 years) healthy adults were recruited to undertake the SOT, which consisted of six conditions aimed at removing or disrupting the visual, vestibular, and proprioceptive senses. During these six SOT conditions, functional near‐infrared spectroscopy (fNIRS), consisting of eight transmitter‐receiver optode pairs (four channels over the left and right DLPFC), was used to measure hemodynamic responses (i.e., changes in oxy‐ [O2Hb] and deoxyhemoglobin [HHb]) from the bilateral DLPFC.ResultsOur results show an increase in bilateral DLPFC activation (i.e., increase in O2Hb and concomitant smaller decrease in HHb) with increasing sensory complexity in both young and older adults. The increase in left and right DLPFC activation during more complex sensory conditions was greater, which was concomitant with reduced balance performance in older adults compared to younger adults. Furthermore, we observed a right lateralized DLPFC activation in younger adults. Finally, a significant positive association was observed between balance performance and increased bilateral DLPFC activation particularly for SOT conditions with greater sensory disruptions.ConclusionOur findings highlight the involvement of the DLPFC in maintaining postural control, particularly during complex sensory tasks, and provide direct evidence for the role of the DLPFC during postural control of a clinically relevant measure of balance.

Highlights

Human postural control is reliant on visual, vestibular, and proprio‐ ceptive senses to maintain a stable upright stance (Blumle, Maurer, Schweigart, & Mergner, 2006)
The concept of functional near‐infrared spectroscopy (fNIRS) as well as functional magnetic resonance imaging (fMRI) is based on the assumption that brain activity leads to an increase in regional cerebral blood flow due to neurovascu‐ lar coupling mechanisms, which is reflected in the fNIRS hemody‐ namic response signal by an increase in oxyhemoglobin [O2Hb] and decrease in deoxyhemoglobin [HHb] concentration levels (Ferrari & Quaresima, 2012)
Activation was associated with better balance performance as the level of sensory complexity increased. This was characterized by an increase in bilateral dorsolateral prefrontal cortex (DLPFC) O2Hb in both age‐groups for all eyes closed conditions and those using the sway‐referenced sur‐ face, which was greater in older compared to younger adults

Summary

Introduction

Human postural control is reliant on visual, vestibular, and proprio‐ ceptive senses to maintain a stable upright stance (Blumle, Maurer, Schweigart, & Mergner, 2006). Karim, Fuhrman, Sparto, Furman, and Huppert (2013) were the first to successfully use fNIRS to measure cortical hemodynamic responses from the frontal, temporal, and parietal regions of the brain in young healthy participants during the SOT Their results showed bilateral activation in the temporal–parietal areas (i.e., superior temporal and supramarginal gyri) when both vision and proprioceptive information were degraded. Methods: Twenty young (18–25 years) and 18 older (66–73 years) healthy adults were recruited to undertake the SOT, which consisted of six conditions aimed at re‐ moving or disrupting the visual, vestibular, and proprioceptive senses During these six SOT conditions, functional near‐infrared spectroscopy (fNIRS), consisting of eight transmitter‐receiver optode pairs (four channels over the left and right DLPFC), was used to measure hemodynamic responses (i.e., changes in oxy‐ [O2Hb] and deoxy‐ hemoglobin [HHb]) from the bilateral DLPFC. Conclusion: Our findings highlight the involvement of the DLPFC in maintaining pos‐ tural control, during complex sensory tasks, and provide direct evidence for the role of the DLPFC during postural control of a clinically relevant measure of balance

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