Dynamics of sensorimotor plasticity during spatial finger augmentation

How does the brain integrate artificial body extensions into its somatosensory representations? Prior work shows that the body and technology are represented simultaneously, but little is known about how these representations evolve dynamically across different sensorimotor interaction phases. To fill this gap, we investigated the dynamics of somatosensory plasticity using a custom-built wearable finger-extension device that elongated users’ fingers by 10 cm, spatially augmenting their reachable workspace. Across four time points, before, during (pre-and post-use), and after device wear, participants completed a high-density proprioceptive mapping task to measure representations of the biological and artificial fingers. We observed three distinct phases of plasticity. First, wearing the finger-extension device led to a contraction of the perceived length of the biological finger. Second, after active use, the represented lengths of the biological and artificial fingers stretched significantly, an effect absent when participants trained with a non-augmenting control device. Third, a post-removal aftereffect on the biological finger representation was observed. These results demonstrate that wearable finger extensions that provide spatial augmentation are rapidly integrated into body representations, with dynamic proprioceptive adjustments shaped by structural and functional properties of the device. This work advances our understanding of how the sensorimotor system accommodates artificial extensions and highlights the potential for body-augmenting technologies to be intuitively integrated within the sensorimotor system.