P31 The hands are immediately perceived closer to body midline in the absence of vision
Qureshi H[1,2], Butler AB[1,2], Kerr GK[3], Gandevia SC[1,2], Héroux MH[1,2]
- Neuroscience Research Australia, Sydney, NSW, Australia
- University of New South Wales, Sydney, Australia
- Queensland University of Technology, Brisbane, Australia
Our sense of limb position is crucial to plan a motor task such as reaching for an object, interact with our environment and perform daily activities (1). Although we can precisely and accurately perceive the location of our hands when they are visible, we are understandably less accurate when we cannot see our hands. In 30 healthy adults we investigated how horizontal distance of the hand from body midline and the presence of the other hand influences these errors in perceived hand location. Participants reported perceived location of their unseen right hand immediately after it was placed 10, 20 or 30 cm to the right or left of body midline, with or without the left hand also placed 10 cm away from the right hand. Across all positions, the right hand was perceived closer to body midline compared to its actual location. Importantly, the size of this underestimation increased linearly with distance from body midline (slope 0.77 [0.74 to 0.81], mean [95% CI]). Compared to when it was to the left of body midline, the right hand was perceived 2.1 cm [1.6 to 2.7] closer to body midline when it was located to the right. Presence of the other hand did not affect perceived location (-0.54 cm [-1.10 to 0.02]). Without vision, healthy adults make immediate and systematic errors in perceived hand location across the workspace. These results are important to interpret future studies of perceived hand location in patients with motor impairment.
- Proske U & Gandevia SC (2012) Physiol Rev 92, 1651-1697