Gawryszewski L G, Thomaz T G, Machado-Pinheiro W, Sant'Anna A N
Departamento de Neurobiologia, Universidade Federal Fluminense, Niterói, RJ, Brasil.
Braz J Med Biol Res. 1994 Jan;27(1):67-73.
Simple reaction time (RT) to a peripheral visual target is shortened when a non-informative cue is flashed at target location 100-150 ms before target onset (early facilitation). Afterwards, RT to targets appearing at cue location is lengthened (inhibition of return). In the present study we have investigated if these effects arise from the onset and/or from the offset of the cue and the time-dependence of these effects. Twelve subjects were asked not to respond to a non-informative cue (S1) appearing on a computer screen 6 degrees to the right or to the left of a fixation point (FP), but to respond, by pressing a key, to a target (S2) occurring at 4 degrees from the FP in the same hemifield as S1 or in the opposite hemifield. There were two different types of trials. In both, a brief auditory stimulus (W) occurring 700 ms after the onset of FP warned the subject that S2 would appear 100, 200, 300, 500 or 800 ms later. Trials where the onset of S1 coincides with W and S1 remains on until the response to S2 are called ON trials. In OFF trials, S1 onset occurs at the beginning of the trial and its offset coincides with W. We found that in ON trials, RTs to S2 occurring ipsi- or contralaterally to S1 did not differ. In contrast, S1 offset elicited an inhibition of its hemifield beginning at least 100 ms after S1 offset and extending up to 800 ms.
当一个非信息性线索在目标出现前100 - 150毫秒在目标位置闪现时，对周边视觉目标的简单反应时（RT）会缩短（早期促进）。之后，对出现在线索位置的目标的反应时会延长（返回抑制）。在本研究中，我们调查了这些效应是由线索的开始和/或结束引起的，以及这些效应的时间依赖性。12名受试者被要求不对出现在电脑屏幕上固定点（FP）右侧或左侧6度的非信息性线索（S1）做出反应，而是通过按键对与S1在同一半视野或相反半视野中距离FP 4度处出现的目标（S2）做出反应。有两种不同类型的试验。在这两种试验中，在FP出现后700毫秒出现的一个简短听觉刺激（W）会提醒受试者S2将在100、200、300、500或800毫秒后出现。S1的开始与W同时出现且S1一直持续到对S2做出反应的试验称为ON试验。在OFF试验中，S1在试验开始时出现，其结束与W同时。我们发现，在ON试验中，对与S1同侧或对侧出现的S2的反应时没有差异。相比之下，S1的结束在S1结束后至少100毫秒开始引起其半视野的抑制，并持续到800毫秒。
