| 摘要: | 本計畫書的重點在於使用穿顱磁刺激做為研究工具，探討大腦在處理視覺搜尋時，腦中各相關部位(例如: 額葉眼動區; 頂葉後區; 初級視覺皮質區) 對於視覺搜尋的必要性，以及這些部位彼此在處理此項功能的時間上及功能上的交互作用。要瞭解大腦是如何執行運作認知功能，研究者不只需要有相關性的證據(如: 腦造影技術; 腦電波偵測技術提供的訊息)，還需要釐清各個腦部位對於這個認知功能的必要性。這種認知功能與大腦部位之間的必然律與因果律，過去只能藉由研究腦傷病人來獲得證實，然而這方面的研究已漸由穿顱磁刺激的研究取代。穿顱磁刺激是一項不具侵犯性且已廣泛運用在人腦科學研究的新興實驗工具，這項工具最大的特點是可以瞬間干擾 (小於10 毫秒) 特定腦部區域，以驗證這區域在特定時間點對認知功能執行的必要性。相較於腦傷病人的研究，穿顱磁刺激具有優越的時間上與空間上的定位能力，更重要的是它的干擾效果是完全可逆轉的。本子計畫將使用各類的穿顱磁刺激實驗方法與視覺搜尋實驗典範，來探討腦中有關部位在視覺搜尋知覺促發; 視覺搜尋動作促發; 視覺搜尋知覺學習以及視覺搜尋辨識能力的必要性，以及各相關部位在時間上及功能上的交互作用，以驗證視覺搜尋的理論與其大腦運作的神經機制。 The goals of the application are to investigate the sensory and executive role of the frontal eye fields (FEF, Brodmann』s area 8) and the posterior parietal cortex (PPC, Brodmann』s area 7) and primary visual cortex (V1, Brodmann』s area 17) in visual cognition and to integrate the findings with comparable data from studies of these three cortical areas I have studied: the posterior parietal cortex (Juan and Walsh 2000; Juan et al., 2001), cortical visual area V1 (Juan and Walsh, 2003; Juan et al., 2004) and frontal eye fields (Muggleton et al., 2003). Parietal cortex has long been implicated in spatial attention and neglect and one of the main projection areas of the parietal cortex is to the frontal eye fields. The pattern of these projections suggest that FEF receives information about both visual attributes of features and spatial information about the location of objects that can be used to direct saccades (e.g. Schall et al., 1995) and FEF is commonly thought to be the final stage of cortical processing for the generation of visually-guided saccades (Collin & Cowey,. 1980; Collin et al., 1982; Bruce & Goldberg, 1985; Seagraves & Goldberg, 1987; Schall, 1991; Dawsonville et al., 1992; Seagraves, 1992). Partly because of this view of the role of FEF, the single unit recordings that report saccade-related activity that increases linearly 100-200 msec prior to a saccade (Goldberg & Bushnell, 1981) have received more emphasis than recordings of units in FEF that show them to be essentially sensory in their responses (Carpenter, 1988, 1998, 2000). Many brain imaging techniques, such as fMRI, ERPs and MEG, correlate brain activation and cognitive processes. To investigate the mechanisms of cognitive processes we need to go beyond the correlation evidence and determine the link of cause and necessity between brain activation and cognition. The causality and necessity between brain and behavior has conventionally been established by lesion studies. Transcranial magnetic stimulation (TMS), a noninvasive technique, offers some solutions to many limitations of lesion experiments. The very first TMS work on cognition was in fact done with a visual cognition task by Amassian et al (1989). As the modern TMS technique did not become available until 1985 and its application to research in cognitive neuroscience only became prevalent in recent years, together with my previous findings in brain stimulation and visual cognition (Juan and Walsh, 2003; Muggleton et al., 2003; Juan et al., 2004; Juan, 2002; Juan and Walsh, 2000; Juan and Walsh, 2001; Juan et al., 2003; Shorter-Jacobi et al., 2003), I have a solid grounding with which to explore the conclusive necessity and temporal involvement of FEF, PPC and V1 in visual search and related issues. 研究期間：9308 ~ 9407 |
