Terao Y, Fukuda H, Ugawa Y, Hikosaka O, Hanajima R, Furubayashi T, Sakai K, Miyauchi S, Sasaki Y, Kanazawa I
Department of Neurology, Division of Neuroscience, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, USA.
J Neurophysiol. 1998 Aug;80(2):936-46. doi: 10.1152/jn.1998.80.2.936.
We investigated the topography of human cortical activation during an antisaccade task by focal transcranial magnetic stimulation (TMS). We used a figure-eight shaped coil, with the stimulus intensity set just above the threshold for activation of the hand motor areas but weak enough not to elicit blinks. TMS was delivered at various time intervals (80, 100, and 120 ms) after target presentation over various sites on the scalp while the subjects performed the antisaccade task. It was possible to elicit a mild but significant delay in saccade onset over 1) the frontal regions (a region 2-4 cm anterior and 2-4 cm lateral to hand motor area) and 2) posterior parietal regions (6-8 cm posterior and 0-4 cm lateral to hand motor area) regardless of which hemisphere was stimulated. The frontal regions were assumed to correspond to a cortical region including the frontal eye fields (FEFs), whereas the parietal regions were assumed to represent a wide region that includes the posterior parietal cortices (PPCs). The regions inducing the delay shifted from the posterior parietal regions at an earlier interval (80 ms) to the frontal regions at a later interval (100 ms), which suggested an information flow from posterior to anterior cortical regions during the presaccadic period. At 120 ms, the effect of TMS over the frontal regions still persisted but was greatly diminished. Erroneous prosaccades to the presented target were elicited over a wide cortical region including the frontal and posterior parietal regions, which again showed a forward shift with time. However, the distribution of effective regions exhibited a clear contralateral predominance in terms of saccade direction. Our technique provides a useful method not only for detecting the topography of cortical regions active during saccadic eye movement, but also for constructing a physiological map to visualize the temporal evolution of functional activities in the relevant cortical regions.
我们通过局灶性经颅磁刺激（TMS）研究了反扫视任务期间人类皮质激活的地形图。我们使用了一个八字形线圈，刺激强度设定在刚好高于手部运动区激活阈值之上，但又弱到不足以引起眨眼。在受试者执行反扫视任务时，在目标呈现后的不同时间间隔（80、100和120毫秒），在头皮上的不同部位施加TMS。无论刺激哪个半球，在1）额叶区域（手部运动区前方2 - 4厘米、外侧2 - 4厘米的区域）和2）顶叶后部区域（手部运动区后方6 - 8厘米、外侧0 - 4厘米的区域）都有可能引起扫视起始的轻度但显著延迟。额叶区域被认为对应于包括额叶眼区（FEFs）的皮质区域，而顶叶区域被认为代表包括顶叶后皮质（PPCs）的广泛区域。引起延迟的区域从较早时间间隔（80毫秒）的顶叶后部区域转移到较晚时间间隔（100毫秒）的额叶区域，这表明在扫视前阶段信息从后皮质区域向前皮质区域流动。在120毫秒时，额叶区域的TMS效应仍然存在，但大大减弱。在包括额叶和顶叶后部区域的广泛皮质区域引发了对呈现目标的错误顺向扫视，并且随着时间推移再次出现向前转移。然而，就扫视方向而言，有效区域的分布表现出明显的对侧优势。我们的技术不仅为检测扫视眼动期间活跃的皮质区域地形图提供了一种有用的方法，还为构建生理图谱以可视化相关皮质区域功能活动的时间演变提供了方法。
