Beyvers Marie C, Fraser Lindsey E, Fiehler Katja
Department of Psychology, Justus Liebig University Giessen, Giessen, Germany.
Center for Vision Research, York University, Toronto, ON, Canada.
Front Hum Neurosci. 2022 Feb 24;16:795886. doi: 10.3389/fnhum.2022.795886. eCollection 2022.
Predictable somatosensory feedback leads to a reduction in tactile sensitivity. This phenomenon, called , relies on a mechanism that uses an efference copy of motor commands to help select relevant aspects of incoming sensory signals. We investigated whether tactile suppression is modulated by (a) the task-relevancy of the predicted consequences of movement and (b) the intensity of related somatosensory feedback signals. Participants reached to a target region in the air in front of a screen; visual or tactile feedback indicated the reach was successful. Furthermore, tactile feedback intensity (strong vs. weak) varied across two groups of participants. We measured tactile suppression by comparing detection thresholds for a probing vibration applied to the finger either early or late during reach and at rest. As expected, we found an overall decrease in late-reach suppression, as no touch was involved at the end of the reach. We observed an increase in the degree of tactile suppression when strong tactile feedback was given at the end of the reach, compared to when weak tactile feedback or visual feedback was given. Our results suggest that the extent of tactile suppression can be adapted to different demands of somatosensory processing. Downregulation of this mechanism is invoked only when the consequences of missing a weak movement sequence are severe for the task. The decisive factor for the presence of tactile suppression seems not to be the predicted action effect as such, but the need to detect and process anticipated feedback signals occurring during movement.
可预测的体感反馈会导致触觉敏感性降低。这种现象被称为 ，它依赖于一种机制，该机制利用运动指令的传出副本，以帮助选择传入感觉信号的相关方面。我们研究了触觉抑制是否受以下因素调节：（a）运动预期后果的任务相关性；（b）相关体感反馈信号的强度。参与者伸手触摸屏幕前方空气中的目标区域；视觉或触觉反馈表明伸手动作成功。此外，两组参与者的触觉反馈强度（强与弱）有所不同。我们通过比较在伸手过程中和静止时早期或晚期施加于手指的探测振动的检测阈值来测量触觉抑制。正如预期的那样，我们发现伸手动作后期的抑制总体上有所降低，因为在伸手动作结束时没有涉及触摸。与给予弱触觉反馈或视觉反馈相比，当在伸手动作结束时给予强触觉反馈时，我们观察到触觉抑制程度增加。我们的结果表明，触觉抑制的程度可以适应体感处理的不同需求。只有当错过一个弱运动序列的后果对任务来说很严重时，才会调用这种机制的下调。触觉抑制存在的决定性因素似乎不是预期的动作效果本身，而是检测和处理运动过程中预期反馈信号的需求。
