Department of Psychology, The University of Tokyo, Tokyo, Japan.
Exp Brain Res. 2021 Jan;239(1):237-244. doi: 10.1007/s00221-020-05971-z. Epub 2020 Nov 2.
Several studies have shown that space immediately surrounding the body, or the peripersonal space is represented differently in the brain from the more distant extra-personal space. Moreover, the boundary of peripersonal space can be extended to space surrounding the tip of a tool held by the hand. However, it is not known if tools need to be connected to the body to modulate the peripersonal space. We used a line bisection task to investigate whether peripersonal space representation surrounds a virtual hand avatar that is disconnected from the body. Healthy participants conducted a line bisection task by responding with either a virtual hand avatar or a laser pointer. The to-be-bisected lines were presented either in peripersonal or extra-personal space. When the lines were placed in extra-personal space, the virtual hand avatar was presented near the line such that the hand avatar was far from participants and disconnected from their bodies. Results indicated a shift in the line bisection bias from the left to the right as the line presentation distance increased when using the laser pointer, whereas no shift in bias was observed when using the virtual hand avatar. This result indicates that objects resembling human hands presented even at a distance and disconnected from the body can be integrated into the peripersonal space, which suggests that peripersonal space representation is more flexible than previously reported.
已有多项研究表明，身体周围的空间（即近体空间）在大脑中的表征不同于更远的体外空间。此外，近体空间的边界可以扩展到手持工具的尖端周围的空间。但是，目前尚不清楚工具是否需要与身体相连才能调节近体空间。我们使用了一种线二分任务来研究与身体断开连接的虚拟手替身是否能围绕近体空间进行表征。健康参与者通过使用虚拟手替身或激光指示器来完成线二分任务。待二分的线呈现于近体空间或体外空间。当线呈现于体外空间时，虚拟手替身被放置在线附近，使得手替身远离参与者且与他们的身体断开连接。结果表明，当使用激光指示器时，随着线呈现距离的增加，线二分偏差从左侧向右侧转移，而当使用虚拟手替身时，未观察到偏差的转移。这一结果表明，即使在远处且与身体断开连接的类似于人手的物体也可以被整合到近体空间中，这表明近体空间的表征比之前报道的更加灵活。
