School of Psychology, Cardiff University, Tower Building, Park place, Cardiff, CF10 3AT, UK.
Exp Brain Res. 2010 Oct;206(4):441-8. doi: 10.1007/s00221-010-2417-x. Epub 2010 Sep 25.
It is widely accepted that regions within the dorsal medial frontal cortex are involved in the control of voluntary action. However, recent evidence suggests that a subset of these regions may also be important for unconscious and involuntary motor processes. Indeed, Sumner et al. (Neuron 54:697-711, 2007) showed that two patients with micro-lesions of the supplementary motor area (SMA) and supplementary eye field (SEF) demonstrated an absence of unconscious inhibition as evoked by masked-prime stimuli, while pre-SMA damage had no such effect. Here, we employ fMRI and a similar masked-prime task to test whether SMA and pre-SMA are similarly dissociated in healthy volunteers. Reaction times (RT) revealed that responses to compatible trials were slower than those to incompatible trials (negative compatibility effect, NCE), indicating automatic inhibition in every participant. BOLD signals in the SMA were modulated by prime compatibility, showing greater signal for compatible trials, but there was no change in pre-SMA. There was also no modulation in the hand motor cortex (HMC). These findings imply that the SMA is involved in automatic suppression of manual motor plans.
人们普遍认为，背内侧额前皮质内的区域参与了对随意运动的控制。然而，最近的证据表明，这些区域中的一部分可能对无意识和非自愿的运动过程也很重要。事实上，Sumner 等人（神经元 54：697-711，2007）表明，两名补充运动区（SMA）和补充眼区（SEF）微损伤的患者表现出缺乏由掩蔽启动刺激引起的无意识抑制，而前 SMA 损伤则没有这种影响。在这里，我们使用 fMRI 和类似的掩蔽启动任务来测试 SMA 和前 SMA 是否在健康志愿者中同样分离。反应时间（RT）表明，相容试验的反应比不相容试验慢（负相容性效应，NCE），表明每个参与者都存在自动抑制。SMA 的 BOLD 信号受启动相容性的调节，相容试验的信号更大，但前 SMA 没有变化。手部运动皮层（HMC）也没有变化。这些发现表明，SMA 参与了对手动运动计划的自动抑制。
