McSorley Eugene, Haggard Patrick, Walker Robin
Department of Psychology, University of Reading, Reading, UK.
J Neurophysiol. 2006 Sep;96(3):1420-4. doi: 10.1152/jn.00315.2006. Epub 2006 Apr 19.
Selecting a stimulus as the target for a goal-directed movement involves inhibiting other competing possible responses. Both target and distractor stimuli activate populations of neurons in topographic oculomotor maps such as the superior colliculus. Local inhibitory interconnections between these populations ensure only one saccade target is selected. Suppressing saccades to distractors may additionally involve inhibiting corresponding map regions to bias the local competition. Behavioral evidence of these inhibitory processes comes from the effects of distractors on oculomotor and manual trajectories. Individual saccades may initially deviate either toward or away from a distractor, but the source of this variability has not been investigated. Here we investigate the relation between distractor-related deviation of trajectory and saccade latency. Targets were presented with, or without, distractors, and the deviation of saccade trajectories arising from the presence of distractors was measured. A fixation gap paradigm was used to manipulate latency independently of the influence of competing distractors. Shorter-latency saccades deviated toward distractors and longer-latency saccades deviated away from distractors. The transition between deviation toward or away from distractors occurred at a saccade latency of around 200 ms. This shows that the time course of the inhibitory process involved in distractor related suppression is relatively slow.
选择一个刺激作为目标导向运动的靶点涉及抑制其他竞争性的可能反应。目标刺激和干扰刺激都会激活诸如上丘等地形性眼球运动图谱中的神经元群体。这些群体之间的局部抑制性相互连接确保只选择一个扫视目标。抑制对干扰物的扫视可能还涉及抑制相应的图谱区域，以偏向局部竞争。这些抑制过程的行为证据来自干扰物对眼球运动和手动轨迹的影响。单个扫视最初可能朝着或远离干扰物偏离，但这种变异性的来源尚未得到研究。在这里，我们研究轨迹的干扰物相关偏差与扫视潜伏期之间的关系。呈现带有或不带有干扰物的目标，并测量由于干扰物的存在而产生的扫视轨迹偏差。使用注视间隙范式来独立于竞争性干扰物的影响来操纵潜伏期。潜伏期较短的扫视朝着干扰物偏离，而潜伏期较长的扫视则远离干扰物。朝着或远离干扰物的偏差转变发生在约200毫秒的扫视潜伏期。这表明干扰物相关抑制中涉及的抑制过程的时间进程相对较慢。
