Hospod Valérie, Aimonetti Jean-Marc, Roll Jean-Pierre, Ribot-Ciscar Edith
Neurobiologie Intégrative et Adaptative, Aix-Marseille Université, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6149, 13331 Marseille Cedex 03, France.
J Neurosci. 2007 May 9;27(19):5172-8. doi: 10.1523/JNEUROSCI.0572-07.2007.
The aim of the present study was to test whether fusimotor control of human muscle spindle sensitivity changed when attention was selectively directed to the recognition of an imposed two-dimensional movement in the form of a written symbol. The unitary activities of 32 muscle spindle afferents (26 Ia, 6 II) were recorded by microneurography at the level of the common peroneal nerve. The patterns of firing rate in response to passive movements of the ankle, forming different letters or numbers, were compared in two conditions: control and recognition. No visual cues were given in either condition, but subjects had to recognize and name the character in one condition compared with not paying attention in the control condition. The results showed that 58% of the tested Ia afferents presented modified responses to movements when these had to be recognized. Changes in Ia afferent responses included decreased depth of modulation, increased variability of discharge, and changes in spontaneous activity. Not all changes were evident in the same afferent. Furthermore, the percentage of correctly recognized movements amounted to 63% when changes were observed, but it was only 48% when the primary ending sensitivity was unaltered. The responses of group II afferents were only weakly changed or unchanged. It is suggested that the altered muscle spindle sensitivity is because of selective changes in fusimotor control, the consequence of which might be to feed the brain movement trajectory information that is more accurate.
本研究的目的是测试当注意力被选择性地引导到识别以书面符号形式呈现的二维运动时，人类肌梭敏感性的梭外肌运动控制是否会发生变化。通过微神经图在腓总神经水平记录了32条肌梭传入纤维（26条Ia类、6条II类）的单位活动。在两种情况下比较了对形成不同字母或数字的踝关节被动运动的放电频率模式：对照和识别。两种情况下均未给出视觉提示，但在一种情况下受试者必须识别并说出字符，而在对照情况下则无需注意。结果显示，58%的受试Ia类传入纤维在必须识别运动时对运动的反应出现改变。Ia类传入纤维反应的变化包括调制深度降低、放电变异性增加以及自发活动改变。并非所有变化在同一传入纤维中都很明显。此外，当观察到变化时，正确识别运动的百分比为63%，但当初级终末敏感性未改变时，该百分比仅为48%。II类传入纤维的反应仅略有变化或未发生变化。有人提出，肌梭敏感性的改变是由于梭外肌运动控制的选择性变化，其结果可能是向大脑提供更准确的运动轨迹信息。
