Department of Psychology, New York University, New York, NY 10003.
Center for Neural Science, New York University, New York, NY 10003.
Proc Natl Acad Sci U S A. 2023 Mar 7;120(10):e2219635120. doi: 10.1073/pnas.2219635120. Epub 2023 Feb 28.
Covert endogenous (voluntary) attention improves visual performance. Human neuroimaging studies suggest that the putative human homolog of macaque frontal eye fields (FEF+) is critical for this improvement, whereas early visual areas are not. Yet, correlational MRI methods do not manipulate brain function. We investigated whether rFEF+ or V1/V2 plays a causal role in endogenous attention. We used transcranial magnetic stimulation (TMS) to alter activity in the visual cortex or rFEF+ when observers performed an orientation discrimination task while attention was manipulated. On every trial, they received double-pulse TMS at a predetermined site (stimulated region) around V1/V2 or rFEF+. Two cortically magnified gratings were presented, one in the stimulated region (contralateral to the stimulated area) and another in the symmetric (ipsilateral) nonstimulated region. Grating contrast was varied to measure contrast response functions (CRFs) for all attention and stimulation combinations. In experiment 1, the CRFs were similar at the stimulated and nonstimulated regions, indicating that early visual areas do not modulate endogenous attention during stimulus presentation. In contrast, occipital TMS eliminates exogenous (involuntary) attention effects on performance [A. Fernández, M. Carrasco, , 4078-4084 (2020)]. In experiment 2, rFEF+ stimulation decreased the overall attentional effect; neither benefits at the attended location nor costs at the unattended location were significant. The frequency and directionality of microsaccades mimicked this pattern: Whereas occipital stimulation did not affect microsaccades, rFEF+ stimulation caused a higher microsaccade rate directed toward the stimulated hemifield. These results provide causal evidence of the role of this frontal region for endogenous attention.
内源性（自愿）注意力掩蔽可提高视觉表现。人类神经影像学研究表明，猕猴额眼区（FEF+）的假定人类同源物对于这种改善至关重要，而早期视觉区域则不然。然而，相关的 MRI 方法不能操纵大脑功能。我们研究了 rFEF+或 V1/V2 是否在内源性注意中起因果作用。当观察者在注意力被操纵的情况下执行方向辨别任务时，我们使用经颅磁刺激（TMS）改变视觉皮层或 rFEF+的活动。在每个试验中，他们在 V1/V2 或 rFEF+周围的预定部位（刺激部位）接受双脉冲 TMS。呈现两个皮质放大的光栅，一个在刺激区域（刺激区域的对侧），另一个在对称（同侧）的非刺激区域。光栅对比度变化以测量所有注意力和刺激组合的对比度响应函数（CRF）。在实验 1 中，刺激和非刺激区域的 CRF 相似，表明在刺激呈现期间早期视觉区域不会调节内源性注意力。相比之下，枕叶 TMS 消除了对外源性（非自愿）注意力对表现的影响[A. Fernández, M. Carrasco, 4078-4084 (2020)]。在实验 2 中，rFEF+刺激降低了整体注意力效应；在注意力集中的位置没有益处，在未注意的位置也没有成本。微扫视的频率和方向性也模仿了这种模式：虽然枕叶刺激不会影响微扫视，但 rFEF+刺激会导致更多指向刺激半视野的微扫视。这些结果提供了该额区对内源性注意力作用的因果证据。
