| 摘要: | 利用腦部干擾與造影技術分離在自然環境和3D刺激的誘發之視覺搜尋相關的腦部功能搜尋是視覺行為中一項重要能力，讓我們得以從眾多視覺干擾刺激的環境中，定位出重要的目標。從過去相關性造影研究(如功能性腦造影，例如Donner等人，2002)和干擾技術(如：跨顱磁刺激)的研究都顯示出許多腦區與視覺搜尋能力有關，尤其當目標和干擾物擁有數種特徵相較於單純特徵搜尋，顯示出這些腦區對於搜尋歷程執行的必要性(Walsh et al., 1998; Muggleton et al., 2003; Juan et al., 2008)。儘管過去研究中認為雙側後頂葉皮質負責廣泛的注意力負荷之處理，而額葉眼動區在傳統上被視為只與眼動控制能力相關，然而有研究顯示這些腦區與成功的搜尋歷程有重要的關聯，因此這些腦區的作用仍尚待釐清。近期研究比較雙側後頂葉皮質和前額眼動區在時間序列上的差異，研究結果顯示額葉眼動區相對於頂葉區較早處理視覺搜尋相關訊息(PPC, Kalla et al., 2008; O'Shea et al., 2004; Ashbridge et al., 1997)，除此之外，當目標誘發眼動，只有施於額葉眼動區的跨顱磁刺激才觀察到干擾效果。因此，可能是額葉眼動區對於視覺刺激處理非常重要，而後頂葉皮質則是用於視覺與動作的訊號轉換，尤其在需要手部反應的情況下。在此計畫中將利用跨顱磁刺激、跨顱微電流刺激、腦造影等技術研究視覺及動作相關腦區之作用，其中包括了額葉眼動區與後頂葉皮質區。此系列實驗的首要目的為建立該區域的在視覺搜尋表現上的功能定位，同時並探討"學習"如何影響這些區域的作用(過去研究指出施予後頂葉皮質磁刺激時，並不會影響已習得且難度較高的視覺搜尋表現)。此外，我們將更進一步研究這些區域在真實自然的情境搜尋下的作用，其中包括在自然環境或是立體刺激中的搜尋作業，以增進學界對於這些腦區在自然環境中的視覺搜尋所扮演的角色之瞭解。 Dissociating functional contributions of brain areas to search performance in natural scenes and in three dimensional stimuli, using brain stimulation and imaging techniques. Search comprises an essential element of our visual behaviour, enabling us to locate objects (targets) against the background of the rest of the environment (distractors). A number of brain areas have been implicated in the success of this, particularly when the target element shares attributes with distracters (i.e. conjunction search performance) in contrast with feature search (e.g. a target defined by one attribute such as colour), by use of correlational imaging techniques (such as fMRI, e.g. Donner et al 2002). Disruptive stimulation techniques, such as transcranial magnetic stimulation (TMS), have illustrated the necessity of a number of these areas (Walsh et al 1998, Muggleton et al 2003, Juan et al 2008). While both posterior parietal cortex, an area implicated in a wide range of attentionally demanding processes, and frontal eye fields, an area traditionally associated with eye movements, have been shown to be important for successful search performance, the contribution of these, and other areas, remains to be clarified in functional terms. Recently the timing of the involvement of these areas in search performance has been compared directly, with that of frontal eye fields (FEF) preceding that of parietal cortex (PPC, Kalla et al 2008, see also O’Shea et al 2004, Ashbridge et al 1997). Additionally, when the presence of a target is indicated with an eye movement, disruption was seen with TMS stimulation of FEF, but not PPC (Muggleton et al, in press). One possibility, therefore, is that FEF is important for the visual processing of the stimuli and that PPC is important for visuomotor transformation specifically when a manual response is required. We propose to start by investigating the relative contributions of areas including FEF and PPC to search in terms of their visual and motor functions using TMS, tDCS, and magnetic resonance imaging. The aims of this series of experiments will be to initially establish the relative functional roles of these areas in visual search performance as well as investigating the effects of learning on the functions of these areas in search performance (TMS delivered over PPC does not affect performance for a learned difficult search, Walsh et al 1998). In addition to this we will further investigate the contribution of these areas to more realistic search, including detecting targets in natural scenes and in three dimensional stimuli, improving the ecological validity of the functional characterization of the areas investigated 研究期間：10008 ~ 10107 |
