Department of Medical and Translational Biology, Umeå University, 901 87 Umeå, Sweden.
Department of Medical and Translational Biology, Umeå University, 901 87 Umeå, Sweden.
Cell Rep. 2024 Sep 24;43(9):114699. doi: 10.1016/j.celrep.2024.114699. Epub 2024 Aug 30.
Proprioception plays a crucial role in motor coordination and self-perception. Muscle spindles are the principal receptors for proprioception. They are believed to encode muscle stretch and signal limb position and velocity. Here, we applied percutaneous pressure to a small area of extensor muscles at the forearm while recording spindle afferent responses, skeletal muscle activity, and hand kinematics. Three levels of sustained pressure were applied on the spindle-bearing muscle when the hand was relaxed and immobile ("isometric" condition) and when the participant's hand moved rhythmically at the wrist. As hypothesized to occur due to compression of the spindle capsule, we show that muscle pressure is an "adequate" stimulus for human spindles in isometric conditions and that pressure enhances spindle responses during stretch. Interestingly, release of sustained pressure in isometric conditions lowered spindle firing below baseline rates. Our findings urge a re-evaluation of muscle proprioception in sensorimotor function and various neuromuscular pathologies.
本体感觉在运动协调和自我感知中起着至关重要的作用。肌梭是本体感觉的主要感受器。它们被认为可以编码肌肉拉伸，并发出肢体位置和速度的信号。在这里，我们在手背伸肌的小区域上施加经皮压力，同时记录肌梭传入反应、骨骼肌活动和手部运动学。当手放松且不动（“等长”条件）以及当参与者的手在手腕处有节奏地移动时，在手背伸肌上施加三个级别的持续压力。正如预期的那样，由于肌梭囊的压缩，我们表明肌肉压力是等长条件下人体肌梭的“适当”刺激，并且压力会增强拉伸过程中的肌梭反应。有趣的是，在等长条件下持续压力的释放会使肌梭放电率低于基线水平。我们的发现促使人们重新评估肌肉本体感觉在感觉运动功能和各种神经肌肉疾病中的作用。
