Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Neuroscience

Supervisor

Peters, Sue

Abstract

Light touch sensitivity of the foot sole is typically measured when individuals are seated or lying down; yet, a critical function of foot sole cutaneous feedback is to support standing and walking activities. The objective of this study was to evaluate the differences in how individuals perceive light touch stimulation across the foot sole when they are in different postures. To accomplish this, we measured the light touch perceptual threshold(LTPT) in standing, seated, and supine postures in 19 volunteers (9 males), using Semmes-Weinstein Monofilaments. Perceptual thresholds were calculated at three foot sole locations (1st metatarsal, lateral arch, and heel) in each posture. Perceptual thresholds were significantly higher in the standing condition compared to the seated and supine conditions across all foot locations; perceptual thresholds were significantly higher while seated compared to supine only at the heel and not at the lateral arch or 1st metatarsal. Our results demonstrate that postural changes significantly influence sensitivity across the foot sole. Thus, performing perceptual threshold assessments on the foot sole while standing may offer more relevant insights into the capacity of foot sole cutaneous afferents to convey light touch information in conditions where such feedback plays a vital role in maintaining balance.

Summary for Lay Audience

How can humans manage to stay balanced while standing or walking, without consciously thinking about it? Our ability to do so comes down to how our bodies process sensory information from our environment, specifically from the soles of our feet. This thesis delves into how different body postures – standing, sitting, and lying down – affect our ability to sense stimulations at the foot sole, and what this might mean for how we currently understand balance and movement. Using Semmes-Weinstein Monofilaments, which are like very fine, calibrated fishing lines, we tested how easily people could feel light touches on three areas of their foot sole in three different postures. Our participants were a group of young adults who underwent a series of touch sensitivity tests.

We found that when standing, people were less sensitive to touch on their foot sole compared to seated or lying down, and less sensitive when seated than when lying down. This difference in touch sensitivity suggests that our posture plays a significant role in how we perceive sensory information from our feet. Understanding these differences can help us comprehend how our bodies maintain balance. Older adults and people who have had a stroke or have diabetes might have impaired sensitivity in their feet. So, these insights could help us better understand how sensation works at a fundamental level as a guideline for rehabilitation practices and balance-enhancing tools for people with impaired sensitivity. This research shines light on the complex interaction between our body posture and the sensory feedback from our feet, emphasizing its importance in our daily life for activities like standing and walking. The hope is that this study will help guide innovative strategies to improve balance in high-risk populations.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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