背景:感官再传入对于纠正我们的姿势和动作至关重要,既反身又以认知驱动的方式。它们对于发展和保持我们行动的代理意识也是不可或缺的。在妥协的情况下,例如截肢或先天性肢体缺失的人,或外周和中枢神经系统的疾病,因此,增强的感官反馈具有强大的潜力,神经康复的影响。我们在这里开发了一种不受束缚的振动触觉服装,它提供了与行走相关的感官反馈,这些反馈以非侵入方式重新映射到穿着者的背部。使用所谓的FeetBack系统,我们调查了健康个体是否认为同步重映射反馈对应于他们自己的运动(运动意识),以及触觉运动反馈的时间延迟如何影响运动意识和步行特征(适应).
方法:我们设计了该系统,以重新映射健康参与者脚底的体感信息(N=29),利用振动触觉的明显运动,到两个线性阵列的振动器同侧安装在背面。这模仿了在站立阶段每只脚上质心的平移。干预包括实时或延迟反馈的试验,总共进行了120次试验和大约750个步骤循环,即1500步,每个参与者。根据以前的工作,实验延迟范围从0ms到1500ms,包括一个完整的步进周期(基线跨步时间:µ=1144±9ms,范围986-1379ms)。每次试验后,参与者都被要求报告他们的运动意识。
结果:参与者报告了他们的运动与实时试验的重新映射反馈之间的高度对应(85±3%,µ±σ),和最低对应性的试验与左右反向反馈(22±6%,在600ms延迟)。参与者进一步报告了一个完整的步态周期延迟的试验的高度对应(1200ms延迟时78±4%),这样,运动意识的调制最好表示为正弦关系,反映实际和重新映射的触觉反馈之间的相移(cos模型:与线性拟合相比,残差平方和(RSS)减少了38%,p<0.001)。系统的时间延迟,但仅以正弦方式适度调制参与者的跨步时间(与线性拟合相比,RSS降低了3%,p<0.01)。
结论:我们在这里证明,重新映射的触觉反馈在系统中调节运动意识,步态周期依赖的方式。基于这种方法,FeetBack系统用于提供与用户正在进行的运动相关的增强感官信息,以便他们报告高运动意识,以(重新)同步反馈他们的运动。虽然运动适应在当前健康参与者队列中受到限制,下一步将是评估周围神经系统受损的个体,以及那些与中枢神经系统的条件,如帕金森病,可能会受益于FeetBack系统,既要保持对其运动的代理意识,也要响应重新映射的系统步态适应,自定进度,有节奏的反馈。
BACKGROUND: Sensory reafferents are crucial to correct our posture and movements, both reflexively and in a cognitively driven manner. They are also integral to developing and maintaining a sense of agency for our actions. In cases of compromised reafferents, such as for persons with amputated or congenitally missing limbs, or diseases of the peripheral and central nervous systems, augmented sensory feedback therefore has the potential for a strong, neurorehabilitative impact. We here developed an untethered vibrotactile garment that provides walking-related sensory feedback remapped non-invasively to the wearer\'s back. Using the so-called FeetBack system, we investigated if healthy individuals perceive synchronous remapped feedback as corresponding to their own movement (motor awareness) and how temporal delays in tactile locomotor feedback affect both motor awareness and walking characteristics (adaptation).
METHODS: We designed the system to remap somatosensory information from the foot-soles of healthy participants (N = 29), using vibrotactile apparent movement, to two linear arrays of vibrators mounted ipsilaterally on the back. This mimics the translation of the centre-of-mass over each foot during stance-phase. The intervention included trials with real-time or delayed feedback, resulting in a total of 120 trials and approximately 750 step-cycles, i.e. 1500 steps, per participant. Based on previous work, experimental delays ranged from 0ms to 1500ms to include up to a full step-cycle (baseline stride-time: µ = 1144 ± 9ms, range 986-1379ms). After each trial participants were asked to report their motor awareness.
RESULTS: Participants reported high correspondence between their movement and the remapped feedback for real-time trials (85 ± 3%, µ ± σ), and lowest correspondence for trials with left-right reversed feedback (22 ± 6% at 600ms delay). Participants further reported high correspondence of trials delayed by a full gait-cycle (78 ± 4% at 1200ms delay), such that the modulation of motor awareness is best expressed as a sinusoidal relationship reflecting the phase-shifts between actual and remapped tactile feedback (cos model: 38% reduction of residual sum of squares (RSS) compared to linear fit, p < 0.001). The temporal delay systematically but only moderately modulated participant stride-time in a sinusoidal fashion (3% reduction of RSS compared a linear fit, p < 0.01).
CONCLUSIONS: We here demonstrate that lateralized, remapped haptic feedback modulates motor awareness in a systematic, gait-cycle dependent manner. Based on this approach, the FeetBack system was used to provide augmented sensory information pertinent to the user\'s on-going movement such that they reported high motor awareness for (re)synchronized feedback of their movements. While motor adaptation was limited in the current cohort of healthy participants, the next step will be to evaluate if individuals with a compromised peripheral nervous system, as well as those with conditions of the central nervous system such as Parkinson\'s Disease, may benefit from the FeetBack system, both for maintaining a sense of agency over their movements as well as for systematic gait-adaptation in response to the remapped, self-paced, rhythmic feedback.