自1980年代中期開始，跨顱磁刺激(transcranial magnetic stimulation; TMS)在實驗心理學及神經科學領域已廣泛的被應用在大腦不同層次功能的探討。這項技術可藉由暫時干擾健康受試者的腦區以探討特定腦區對於認知歷程的影響，不再只是依靠特定腦區意外損壞或進行手術的病人來進行研究。當前跨顱磁刺激技術被應用於許多的實驗典範，包括在認知實驗中的虛擬病變技術或給予刺激以探討神經運動系統，並且有研究發現跨顱磁刺激係為神經精神疾病潛在的治療方法，例如治療憂鬱症及思覺失調症。儘管如此，許多刺激方法的採用並不是基於跨顱磁刺激對於神經系統的影響的背景知識，這意味著我們目前對於不同腦區受磁刺激干擾後的性質變異並不清楚。然而，這個問題在許多的情形中並不重要，特別是若只想探究在特定的作業中是否包含特定腦區的運作或是此腦區的活化時間點為何，但若是想探討在作業中所活化的腦區其性質為何，效果的解釋則臆測成分居多。例如，在聯合視覺搜尋的作業中，受試者需找尋包含兩個特徵的目標物，過去研究發現在此作業中包含了許多腦區的運作，並且也發現不同腦區在不同時間點作用，然而對於這些腦區作用的性質為何尚存有很多的臆測。因此，本計畫旨在探討跨顱磁刺激對認知作業表現的影響並結合擴散漂移模型分析方法以提供磁刺激影響的內在性質訊息。計畫目標為(1)了解跨顱磁刺激對於認知表現的影響是否能藉由擴散漂移模型分析而更清楚的被量測；(2)判定不同磁刺激方法作用於不同腦區在認知作業表現上是否能揭露出不同神經運作的機制；(3)結合跨顱磁刺激及腦電波以了解磁刺激對腦區影響內在性質的解讀；(4)檢測跨顱磁刺激對認知表現的影響效果是否單純為刺激神經所造成;或者只是由於跨顱磁刺激進行時所引起可能的不適或雜訊造成。本研究計畫成果的可能貢獻在於:能不增加實驗設計的複雜性且大大擴展跨顱磁刺激在認知研究中的實用性，進而逐步幫助且應用於臨床醫學的治療。 ;The use of transcranial magnetic stimulation (TMS) has expanded rapidly since its application became possible in a meaningful way in the experimental psychology/neuroscience environment in the mid-1980s. This reflects this technique allowing the contribution of different brain areas to a range of processes to be investigated by disruption in healthy individuals, rather than requiring a patient with a lesion in an ‘appropriate’ cortical area (either as the result of an accident or surgery) to be available. It is now employed experimentally in a variety of paradigms, including as a ‘virtual-lesion’ technique in cognitive experiments, or to deliver stimulation to investigate the neuro-motor system. It has also been investigated as a potential treatment in neuropsychiatric disorders such as depression and schizophrenia. Despite this, many of the stimulation approaches are not particularly based around knowledge of the effects of TMS on neural systems (but see theta-burst TMS, Huang et al., 2005), meaning the nature of disruption of any stimulated area is unclear. While in many cases this is not important, particularly if the experiment is simply trying to determine whether a brain area is involved in a task (or what the timing of such involvement is), when the nature of the contribution of the area is of interest then interpretation of effects is more speculative. An example of this is in the case of search for a visual target defined by a combination of attributes (conjunction visual search). While several brain areas have been shown to be involved in performing this task, and with different times of involvement, the differences in the nature of their contribution is much less clear. Here it is proposed to investigate TMS effects on task performance in combination with drift diffusion model (DDM) based analysis, which, by analysis of response time and accuracy data, can provide more detailed measures that can be related to neurophysiological data and potentially provide insight into the nature of effects. This project therefore aims to assess whether the effects of TMS on task performance can be more clearly assessed using DDM analysis; to determine if such an approach can inform about any differences in the contribution to different brain areas to performance of tasks where multiple areas have been shown to be involved (such as visual search); to see if this can strengthen (and be strengthened by) combined EEG-TMS investigations; and assess whether such an approach can help with determining whether a TMS-induced effect is cognitive in nature, rather than due to ‘side-effects’, such as discomfort or noise associated with TMS delivery. Should this approach be successful it has the potential to greatly expand the utility of TMS in cognitive investigations without a significant increase in complexity of the experimental design.
