追踪偏侧化准备电位中快速视觉运动激活的连续波。
Tracing sequential waves of rapid visuomotor activation in lateralized readiness potentials.
作者信息
Vath N, Schmidt T
机构信息
University of Göttingen, Department of Psychology, Gosslerstr. 14, D-37073 Göttingen, Germany.
出版信息
Neuroscience. 2007 Mar 2;145(1):197-208. doi: 10.1016/j.neuroscience.2006.11.044. Epub 2007 Jan 29.
Feedforward activation processes are widely regarded as crucial for the automatic initiation of motor responses, whereas recurrent processes are often regarded as crucial for visual awareness. Here, we used a set of behavioral criteria to evaluate whether rapid processing in the human visuomotor system proceeds as would be expected of a feedforward system that works independent of visual awareness. We measured lateralized readiness potentials (LRPs) for key-press responses to color targets ("masks") preceded by masked color primes mapped onto the same or opposite response, and traced the time-course of motor activation as a function of different prime and mask characteristics. LRP time-courses showed that initial motor activation occurred in prime direction and was time-locked to prime onset. Response activation was then captured on-line by the mask signal, with motor activation now time-locked to the mask and proceeding in mask direction. Crucially, the time-course of early activation by the prime was independent of all mask characteristics. This invariance in early priming effects contrasted with large differences in visual awareness for the prime produced by different masks. Results suggest that primed responses to color stimuli are controlled by feedforward waves of activation sequentially elicited by prime and mask signals traveling rapidly enough to escape the recurrent processes leading to backward masking.
前馈激活过程被广泛认为对运动反应的自动启动至关重要,而循环过程通常被认为对视觉意识至关重要。在这里,我们使用了一组行为标准来评估人类视觉运动系统中的快速处理是否像一个独立于视觉意识工作的前馈系统那样进行。我们测量了对颜色目标(“掩蔽物”)按键反应的侧化准备电位(LRP),这些颜色目标之前有映射到相同或相反反应的掩蔽颜色启动刺激,并追踪了运动激活的时间进程作为不同启动刺激和掩蔽物特征的函数。LRP时间进程表明,初始运动激活发生在启动刺激方向,并与启动刺激开始时间锁定。然后,反应激活被掩蔽信号在线捕获,此时运动激活与掩蔽物时间锁定并沿掩蔽物方向进行。至关重要的是,启动刺激早期激活的时间进程与所有掩蔽物特征无关。这种早期启动效应的不变性与不同掩蔽物产生的启动刺激在视觉意识上的巨大差异形成对比。结果表明,对颜色刺激的启动反应由前馈激活波控制,这些激活波由启动刺激和掩蔽信号依次引发,传播速度足够快,能够避开导致逆向掩蔽的循环过程。