Affiliation:
1. School of Kinesiology University of British Columbia Vancouver British Columbia Canada
2. Department of Health and Rehabilitation Sciences Temple University Philadelphia Pennsylvania USA
3. Department of Bioengineering Temple University Philadelphia Pennsylvania USA
4. Department of Kinesiology Brock University St. Catharines Ontario Canada
5. Djavad Mowafaghian Centre for Brain Health University of British Columbia Vancouver British Columbia Canada
6. International Collaboration on Repair Discoveries University of British Columbia Vancouver British Columbia Canada
Abstract
AbstractDuring unperturbed bipedal standing, postural control is governed primarily by subcortical and spinal networks. However, it is unclear if cortical networks begin to play a greater role when stability is threatened. This study investigated how initial and repeated exposure to a height‐related postural threat modulates cortical potentials time‐locked to discrete centre of pressure (COP) events during standing. Twenty‐seven young adults completed a series of 90‐s standing trials at LOW (0.8 m above the ground, away from edge) and HIGH (3.2 m above the ground, at edge) threat conditions. Three LOW trials were completed before and after 15 consecutive HIGH trials. Participants stood on a force plate while electroencephalographic (EEG) activity was recorded. To examine changes in cortical activity in response to discrete postural events, prominent forward and backward peaks in the anterior–posterior COP time series were identified. EEG data were waveform‐averaged to these events and the amplitude of event‐related cortical activity was calculated. At the LOW condition, event‐related potentials (ERPs) were scarcely detectable. However, once individuals stood at the HIGH condition, clear ERPs were observed, with more prominent potentials being observed for forward (edge‐directed), compared to backward, COP events. Since forward COP peaks accelerate the centre of mass away from the platform edge, these results suggest there is intermittent recruitment of cortical networks that may be involved in the detection and minimization of postural sway toward a perceived threat. This altered cortical engagement appears resistant to habituation and may contribute to threat‐related balance changes that persist following repeated threat exposure.
imageKey points
While standing balance control is regulated primarily by subcortical and spinal processes, it is unclear if cortical networks play a greater role when stability is threatened.
This study examined how cortical potentials time‐locked to prominent peaks in the anterior–posterior centre of pressure (COP) time series were modulated by exposure to a height‐related postural threat.
While cortical potentials recorded over the primary sensorimotor cortices were scarcely detectable under non‐threatening conditions, clear cortical potentials were observed when individuals stood under conditions of height‐related threat.
Cortical potentials were larger in response to COP peaks directed toward, compared to away from, the platform edge, and showed limited habituation with repeated threat exposure.
Since forward COP peaks accelerate the centre of mass away from the platform edge, these findings suggest that when balance is threatened, there is intermittent recruitment of cortical networks, which may minimize the likelihood of falling in the direction of a perceived threat.
Funder
Natural Sciences and Engineering Research Council of Canada
Cited by
2 articles.
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