Lange J J, Wijers A A, Mulder L J, Mulder G
Experimental and Work Psychology, University of Groningen, The Netherlands.
Biol Psychol. 1999 Jul;50(3):203-33. doi: 10.1016/s0301-0511(99)00009-5.
Two experiments were performed in which the effects of selective spatial attention on the ERPs elicited by unilateral and bilateral stimulus arrays were compared. In Experiment 1, subjects received a series of grating patterns. In the unilateral condition these gratings were presented one at a time, randomly to the right or left of fixation. In the bilateral condition, gratings were presented in pairs, one to each side of fixation. In the unilateral condition standard ERP effects of visual spatial attention were observed. However, in the bilateral condition we failed to observe an attention related posterior contralateral positivity (overlapping the P1 and N1 components, latency interval about 100-250 ms), as reported in several previous studies. In Experiment 2, we investigated whether attention related ERP lateralizations are affected by the task requirement to search among multiple objects in the visual field. We employed a task paradigm identical to that used by Luck et al. (Luck, S.J., Heinze, H.J., Mangun, G.R., Hillyard, S.A., 1990. Visual event-related potentials index focused attention within bilateral stimulus arrays. II. Functional dissociation of P1 and N1 components. Electroencephalogr. Clin. Neurophysiol. 75, 528-542). Four letters were presented to a visual hemifield, simultaneously to both the attended and unattended hemifields in the bilateral conditions, and to one hemifield only in the unilateral conditions. In a focused attention condition, subjects searched for a target letter at a fixed position, whereas they searched for the target letter among all four letters in the divided attention condition (as in the experiment of Luck et al., 1990). In the bilateral focused attention condition, only the contralateral P1 was enhanced. In the bilateral divided attention condition a prolonged posterior positivity was observed over the hemisphere contralateral to the attended hemifield, comparable to the results of Luck et al. (1990). A comparison of the ERPs elicited in the focused and divided attention conditions revealed a prolonged 'search related negativity'. We discuss possible interactions between this negativity and attention related lateralizations. The display search negativity consisted of two phases, one phase comprised a midline occipital negativity, developing first over the ipsilateral scalp, while the second phase involved two symmetrical occipitotemporal negativities, strongly resembling the N1 in their topography. The display search effect could be modelled with a dipole in a medial occipital (possibly striate) region and two symmetrical dipoles in occipitotemporal brain areas. We hypothesize that this effect reflects a process of rechecking the decaying information of iconic memory in the occipitotemporal object recognition pathway.
进行了两项实验，比较了选择性空间注意对单侧和双侧刺激阵列诱发的事件相关电位（ERP）的影响。在实验1中，受试者接收一系列光栅图案。在单侧条件下，这些光栅一次呈现一个，随机出现在注视点的右侧或左侧。在双侧条件下，光栅成对呈现，分别位于注视点的两侧。在单侧条件下，观察到了视觉空间注意的标准ERP效应。然而，在双侧条件下，我们未能观察到先前几项研究中报道的与注意相关的对侧后正波（与P1和N1成分重叠，潜伏期约为100 - 250毫秒）。在实验2中，我们研究了在视野中多个物体间进行搜索的任务要求是否会影响与注意相关的ERP侧化。我们采用了与Luck等人（Luck, S.J., Heinze, H.J., Mangun, G.R., Hillyard, S.A., 1990. 视觉事件相关电位在双侧刺激阵列中指示集中注意。II. P1和N1成分的功能分离。《脑电图学与临床神经生理学》75, 528 - 542）使用的相同任务范式。在双侧条件下，四个字母同时呈现给视觉半视野，包括被注意和未被注意的半视野，而在单侧条件下只呈现给一个半视野。在集中注意条件下，受试者在固定位置搜索目标字母，而在分散注意条件下（如Luck等人1990年的实验），他们在所有四个字母中搜索目标字母。在双侧集中注意条件下，只有对侧P1增强。在双侧分散注意条件下，在被注意半视野对侧的半球上观察到一个延长的后正波，与Luck等人（1990年）的结果相似。对集中注意和分散注意条件下诱发的ERP进行比较，发现了一个延长的“与搜索相关的负波”。我们讨论了这个负波与注意相关侧化之间可能的相互作用。显示搜索负波由两个阶段组成，一个阶段包括中线枕部负波，首先在同侧头皮上出现，而第二个阶段涉及两个对称的枕颞部负波，其地形图与N1非常相似。显示搜索效应可以用枕部内侧（可能是纹状区）的一个偶极子和枕颞脑区的两个对称偶极子来模拟。我们假设这种效应反映了在枕颞物体识别通路中对表象记忆衰减信息进行重新检查的过程。
