Objective. The nervous system subconsciously estimates the state of the body as a weighted average of the information from various sensory sources, where the weights reflect the perceived reliability of each source. Loss of motor functions can be partially compensated using assistive systems (e.g. prostheses), which may also restore somatosensory feedback through tactile stimulation. Whether such artificial feedback is integrated in the neural state estimation process is not known. Approach. In this study, able-bodied subjects performed a grasp force matching task with supplementary non-invasive electrotactile stimulation with a frequency proportional to grasp force magnitude. Before the task, a brief training session taught the subjects to associate the sensation of electrotactile stimulation with the generated grasp force. In some trials, the force–frequency mapping was biased to introduce an unnoticeable mismatch between natural and electrotactile force feedback, thereby provoking the subject to subconsciously estimate the force as a compromise between the two sources of information. Main results. The outcome of this compromise revealed the weights assigned to each feedback type. The grasp forces were significantly affected by the biased mappings, as indicated by the average estimated relative weights (electrotactile: 0.69 0.29; natural: 0.31 0.29). Across subjects, this weight was correlated ) with the improvement in force matching precision when adding the unbiased electrotactile feedback to the natural force feedback, as predicted by maximum likelihood estimation. This shows that even after minimal training the nervous system adopts electrotactile stimulation as a highly reliable source of information that can improve the precision in the estimation of the grip force. Significance. This result has important implications for the restoration of sensory feedback in upper limb prostheses as it indicates that even non-invasive stimulation can be integrated naturally (i.e. subconsciously and effectively) in the motor controlloop.

客观的。神经系统下意识地将身体状态估计为来自各种感官来源的信息的加权平均值，其中权重反映了每个来源的感知可靠性。使用辅助系统（例如假肢）可以部分补偿运动功能的丧失，这也可以通过触觉刺激恢复体感反馈。这种人工反馈是否被集成到神经状态估计过程中尚不得而知。方法。在这项研究中，身体健全的受试者通过补充非侵入性电触觉刺激执行抓握力匹配任务，其频率与抓握力的大小成正比。在任务之前，一个简短的培训课程教会受试者将电触觉刺激的感觉与产生的抓握力联系起来。在一些试验中，力频率映射存在偏差，导致自然力反馈和电触觉力反馈之间存在不明显的不匹配，从而促使受试者下意识地将力估计为两种信息来源之间的折衷。主要结果。这种妥协的结果揭示了分配给每种反馈类型的权重。抓取力受到偏置映射的显着影响，如平均估计相对权重所示（电触觉：0.69 0.29；自然：0.31 0.29）。正如最大似然估计所预测的那样，在所有受试者中，当将无偏电触觉反馈添加到自然力反馈时，该权重与力匹配精度的提高相关。这表明，即使经过最少的训练，神经系统也会采用电触觉刺激作为高度可靠的信息来源，可以提高估计握力的精度。意义。 这一结果对于上肢假肢感觉反馈的恢复具有重要意义，因为它表明即使是非侵入性刺激也可以自然地（即潜意识地和有效地）整合到运动控制回路中。