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

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.

The Immediate Effects of Intermittent Theta Burst Stimulation of the Cerebellar Vermis on Cerebral Cortical Excitability During a Balance Task in Healthy Individuals: A Pilot Study

“…The connections from the DLPFC to the M1 transfer crucial information for the execution of motor output (Cao et al, 2018). The results from Teo et al (2018) highlighted the involvement of the DLPFC in maintaining postural control. Study also demonstrated that the prefrontal cortex (PFC) and temporal-parietal regions were engaged during active balancing process, which was thought to be involved with allocation of attentional demands in standing postural control (Mihara et al, 2008).…”

Altered prefrontal cortex responses in older adults with subjective memory complaints and dementia during dual‐task gait: An fNIRS study

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Functional near-infrared spectroscopy combined with unilateral task-oriented training with and without an orthosis in subacute stroke: A pilot study

“…The probes were placed 3 cm away from each other, to monitor the cortical activation over two 9 cm × 9 cm rectangular elds of view. The electroencephalography (EEG) International 10-20 system Cz, C3, C4 anatomical measurements were used as reference points to ensure that the optical probe setup was placed over 6 ROIs (25) , including the bilateral SMC, PMC and PFC. A three-dimensional (3D)-digitizer was used to record the exact locations of each fNIRS probe for a standard brain before converting these coordinates into the locations of the forty-eight channels in an estimated Montreal Neurological Institute (MNI) space using the MATLAB toolbox NIRS-SPM (26).…”