Characterization of the Sense of Agency over the Actions of Neural-machine Interface-operated Prostheses

摘要

Here we present a protocol which characterizes the sense of agency developed over the control of sensate virtual or robotic prosthetic hands. Psychophysical questionnaires are employed to capture the explicit experience of agency, and time interval estimates (intentional binding) are employed to implicitly measure the sense of agency.

摘要

This work describes a methodological framework that can be used to explicitly and implicitly characterize the sense of agency developed over the neural-machine interface (NMI) control of sensate virtual or robotic prosthetic hands. The formation of agency is fundamental in distinguishing the actions that we perform with our limbs as being our own. By striving to incorporate advanced upper-limb prostheses into these same perceptual mechanisms, we can begin to integrate an artificial limb more closely into the user's existing cognitive framework for limb control. This has important implications in promoting user acceptance, use, and effective control of advanced upper-limb prostheses. In this protocol, participants control a virtual prosthetic hand and receive kinesthetic sensory feedback through their preexisting NMIs. A series of virtual grasping tasks are performed and perturbations are systematically introduced to the kinesthetic feedback and virtual hand movements. Two separate measures of agency are employed: established psychophysical questionnaires (to capture the explicit experience of agency) and a time interval estimate task to capture the implicit sense of agency (intentional binding). Results of this protocol (questionnaire scores and time interval estimates) can be analyzed to quantify the extent of agency formation.

引言

As robotic prostheses become increasingly advanced, the importance of relevant sensory feedback will continue to grow. Sensory feedback affects how humans perceive, interact with, and even integrate machines into their body schema. Recent NMI techniques can now provide prosthetic limb users with intuitive control and achieve sensations associated with touch^{1,2,3,4,5,6,7} and kinesthesia (movement sense)^8,....

方案

This protocol has been previously approved and follows the guidelines of the Cleveland Clinic’s human research ethics committee.

1. Hardware and Software of the NMI

1. Establish each individual participant’s NMI control and feedback so that when they attempt to perform a movement, they see and feel a virtual prosthesis complete that movement.
   1. Generate a hand kinesthetic percept through the participant’s NMI and capture the kinematics of the perceived motion by having the participant demonstrate what they feel using their intact hand.
      NOTE: Techniques to characterize kinesthetic percept kinemati....

结果

The experimental protocol was performed with three amputee participants operating a sensate virtual prosthesis via their NMI⁸ (Figure 1). The setup used a participant-controllable virtual hand moving through preprogrammed kinematic profiles using the MuJoCo HAPTIX physics engine³¹. The virtual hand was displayed on a horizontal monitor in front of the participants at a location spatially congruent with .......

讨论

Here a methodological framework is presented to characterize the experience of agency formed while operating sensate prostheses via NMIs. In this context, agency is particularly relevant as it bridges physical action to the background cognitive processes that shape perception. Through a participant's prosthesis and NMI, we have direct access to a number of key elements that establish the sense of agency: intent, motor output, and movement sensation. Of importance to advanced prosthetic limb control, the tool.......

材料

本文使用的材料清单

姓名	公司	目录编号	评论
LabVIEW 2015，Service Pack 1，版本 15.0.1f2 64 位	National Instruments，美国德克萨斯州奥斯汀完整	版或专业版	我们在 LabVIEW 中编写了自定义软件，以协调虚拟假肢控制与动觉反馈，以及呈现实验条件和记录数据。
8 插槽，USB CompactDAQ 机箱	National Instruments，美国德克萨斯州奥斯汀	cDAQ-9178
±60 V、800 kS/s、12 位、8 通道 C 系列电压输入模块	National Instruments， Austin， TX， USA	NI-9221
100 kS/s/ch 同步、plusmn;10 V，4通道C系列电压输出模块	National Instruments，美国德克萨斯州奥斯汀	NI-9263
定制可穿戴动觉调节器	HDT Global，Solon，OH，USA	N/A	此物品是定制的。其他提供动觉反馈的方法是可以接受的，只要参与者能感觉到手随着虚拟手的动作实时移动的感觉。
MuJoCo 物理引擎，HAPTIX 版本	Roboti LLC，美国华盛顿州雷德蒙德	mjhaptix150	较新版本的 MuJoCo 也应该是可以接受的。我们使用了 MPL Gripper 模型。
Myobock 电极，由 MyoBoy 电池插座中的 Otto Bock EnergyPack 供电	Ottobock， Duderstadt， Germany	电极：13E200=60 电池：757B21 电池插座：757Z191=2	可以使用任何提供放大、过滤和整流 EMG 或神经控制信号的设置。