Dipartimento di Psicologia, Università di Palermo, Palermo, Italy.
Neuropsychologia. 2010 Mar;48(4):1003-10. doi: 10.1016/j.neuropsychologia.2009.11.024. Epub 2009 Dec 16.
In visual search tasks the optimal strategy should utilize relevant information ignoring irrelevant one. When the information at the feature and object levels are in conflict, un-necessary processing at higher level of object shape can interfere with detection of lower level orientation feature. We explored the effects of inhibitory trains of transcranial magnetic stimulation (rTMS) on the right and left parietal cortex in healthy subjects performing two visual search tasks. One task (Task A) was characterised by an object-to-feature interference. The other task (Task B) was without such interference. We found that rTMS of the right parietal cortex significantly reduced reaction times (RTs) in Task A, where object recognition interferes with detection of orientation. This significant RT reduction was present only for the first 10 trials. Interestingly, right parietal rTMS had no effect on Task B. Moreover, rTMS of the left parietal cortex did not modify subjects' RTs in either task. Subjects' accuracy was equally affected by rTMS in both tasks over time. We suggest that inhibition of the right parietal cortex by means of rTMS facilitates feature-based visual search by inhibiting the interfering feature binding and spatial attentional processes. This allows subjects to accomplish Task A faster.
在视觉搜索任务中，最优策略应该利用相关信息忽略不相关信息。当特征和对象层面的信息发生冲突时，对象形状较高层次的不必要处理会干扰较低层次方向特征的检测。我们在执行两项视觉搜索任务的健康受试者中，探索了经颅磁刺激(rTMS)对右侧和左侧顶叶皮层的抑制性训练的影响。一个任务（任务 A）的特征是存在对象到特征的干扰。另一个任务（任务 B）则没有这种干扰。我们发现，右侧顶叶皮层的 rTMS 显著降低了任务 A 中的反应时间（RT），在该任务中，对象识别会干扰方向的检测。这种显著的 RT 降低仅在最初的 10 次试验中出现。有趣的是，右侧顶叶 rTMS 对任务 B 没有影响。此外，左侧顶叶皮层的 rTMS 也没有改变受试者在两个任务中的 RT。随着时间的推移，rTMS 对两个任务中的受试者准确性都有同等影响。我们认为，通过 rTMS 抑制右侧顶叶皮层可以通过抑制干扰的特征绑定和空间注意过程来促进基于特征的视觉搜索，从而使受试者能够更快地完成任务 A。
