Sixth Finger

Can we feel like a part of body to the supernumerary finger actuated by null point?

Embodiment and Neural Representation of an Independent Supernumerary Sixth Finger

This project investigates whether humans can embody and independently control an artificial sixth finger as part of their own body, and how such embodiment is represented in the brain. Unlike traditional prosthetics, which typically substitute for an existing limb or are controlled through movements of innate body parts, our approach enables the control of a supernumerary robotic finger using novel, independent activation patterns.

In our behavioral experiments, participants were able to successfully manipulate the artificial sixth finger independently of their natural fingers, and reported a strong sense of agency and ownership over the supernumerary limb. Subjective evaluations revealed that, under synchronous feedback conditions, participants felt the sixth finger was a natural extension of their own hand (Umezawa et al., 2022).

To explore the neural correlates of this embodiment, we conducted high-field fMRI experiments before and after adaptation to the sixth finger. The results showed significant changes in brain activity within the primary somatosensory and motor cortices specifically associated with the use of the independent finger. These neural changes were closely correlated with increases in subjective embodiment scores, suggesting that the human brain can flexibly reorganize to incorporate new, independently controlled body parts (Arai et al., 2022).

Our findings provide new insights into the plasticity of body representation in the brain, and have important implications for the development of advanced prosthetics and human augmentation technologies.

Please watch the demostration of this project in the video for you to know the overview. The poster shows the overview of this project which I mainly contributed in this project. (Arai et al., 2022)

The other works and contributions can be found in the following citations. (Miyawaki et al., 2022; Takahara et al., 2022; Ueda et al., 2022; Yasuda et al., 2024; Yasuda et al., 2024; Yasuda et al., 2024; Miyawaki-lab, 2022)

References

2024

  1. Effects of an Embodied Artificial Finger on Body Representation in the Brain
    Rei Yasuda, Ken Arai, Yui Takahara, and 3 more authors
    In JNNS2024, Sep 2024
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  2. ICRA
    The ’independent’ Sixth Finger Project
    Rei Yasuda, Yoichi Miyawaki, Ganesh Gaorinshankar, and 5 more authors
    In IEEE-ICRA2024 workshop : The robotics, psychology and neuroscience of body augmentation, Mar 2024
    HTML
  3. SfN
    Neural Differences Induced by the Location of an Embodied Independent Supernumerary Finger
    Rei Yasuda, Ken Arai, Yui Takahara, and 4 more authors
    In Society for Neuroscience 2024, Oct 2024
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2022

  1. Bodily ownership of an independent supernumerary limb: an exploratory study
    Kohei Umezawa, Yuta Suzuki, Gowrishankar Ganesh, and 1 more author
    Scientific reports, Oct 2022
    DOI
  2. SfN
    sfn2022_thumbnail.png
    Neural Correlates of Independent Sixth Finger Embodiment
    Ken Arai, Yui Takahara, Daichi Ueda, and 3 more authors
    In Society for Neuroscience 2022, Nov 2022
    Abs HTML
  3. JIZAI Body in the Human Brain: Embodiment of Independent Artificial Limb
    Yoichi Miyawaki, Ganesh Gowrinshankar, Kohei Umezawa, and 6 more authors
    In Augmented Humans 2022, Mar 2022
    HTML
  4. Neural correlates of the embodiment of an independent supernumerary limb by humans: a functional magnetic resonance imaging study
    Yui Takahara, Ken Arai, Kelssy Kawata, and 3 more authors
    In NEURO2022, Jun 2022
    Bib HTML
  5. Sixth Finger Project: The Optimal Design for Augmentation
    Daichi Ueda, Kohei Umezawa, Yui Takahara, and 4 more authors
    In Augmented Humans 2022, Mar 2022
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  6. 6th Finger Project - promotion video
    Miyawaki-lab
    YouTube, Apr 2022
    Bib Video