Gawryszewski L G, Thomaz T G, Machado-Pinheiro W, Carreiro L R
Departamento de Neurobiologia, Universidade Federal Fluminense, Niteroi, RJ, Brasil.
Braz J Med Biol Res. 1994 Jan;27(1):75-80.
Simple reaction time (RT) to a peripheral visual target (S2) is shortened when a non-informative cue (S1) is flashed at the S2 location 100-150 ms before target onset (early facilitation). Afterwards, RTs to targets appearing at the S1 location are lengthened (inhibition of return). In the present investigation we studied the spatial distribution of the inhibition elicited by the offset of S1. Twelve subjects were asked not to respond to S1 which appeared on a horizontal meridian located 5.5 degrees above the fixation point (FP), but to respond, by pressing a key, to a target (S2) occurring at 5.5 degrees to the left or to the right. S1 could appear at one of 9 locations along this meridian (5.5, 3.5, 1.5, and 0.5 degrees to the left, 0.0 and 0.5, 1.5, 3.5, and 5.5 degrees to the right) and S2 occurred only at the most eccentric positions. Each trial began with the presentation of FP. Five-hundred ms later, S1 appeared and remained on for 700 ms. One hundred or 800 ms after S1 offset, S2 appeared in the same or in the opposite hemifield. We found that the offset of S1 elicits an inhibition (OFF-inhibition) which has the following features: a) it is maximal at cue's position; b) it spreads to other positions in the cued hemifield, and c) it decreases when the time interval between S1 offset and S2 onset increases from 100 to 800 ms.
当一个非信息性线索（S1）在目标（S2）出现前100 - 150毫秒在S2位置闪现时，对周边视觉目标（S2）的简单反应时（RT）会缩短（早期易化）。之后，对出现在S1位置的目标的反应时会延长（返回抑制）。在本研究中，我们研究了S1消失所引发的抑制的空间分布。12名受试者被要求不对出现在位于注视点（FP）上方5.5度的水平子午线上的S1做出反应，而是通过按键对出现在左侧或右侧5.5度处的目标（S2）做出反应。S1可出现在这条子午线上的9个位置之一（向左5.5、3.5、1.5和0.5度，向右0.0、0.5、1.5、3.5和5.5度），且S2仅出现在最偏心的位置。每次试验开始时先呈现FP。500毫秒后，S1出现并持续700毫秒。在S1消失后100或800毫秒，S2出现在同侧或对侧视野。我们发现S1的消失会引发一种抑制（消失抑制），其具有以下特征：a）在线索位置处最大；b）扩散到线索所在半视野的其他位置；c）当S1消失与S2出现之间的时间间隔从100毫秒增加到800毫秒时，这种抑制会减弱。
