Beauchamp Michael S, Yasar Nafi E, Kishan Neel, Ro Tony
Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
J Neurosci. 2007 Aug 1;27(31):8261-7. doi: 10.1523/JNEUROSCI.0754-07.2007.
Previous reports of tactile responses in human visual area MT/V5 have used complex stimuli, such as a brush stroking the arm. These complex moving stimuli are likely to induce imagery of visual motion, which is known to be a powerful activator of MT. The area described as "MT" in previous reports consists of at least two distinct cortical areas, MT and MST. Using functional magnetic resonance imaging, we separately localized human MT and MST and measured their response to vibrotactile stimuli unlikely to induce imagery of visual motion. Strong vibrotactile responses were observed in MST but not in MT. Vibrotactile responses in MST were approximately one-half as large as the response to visual motion and were distinct from those in another visual area previously reported to respond to tactile stimulation, the lateral occipital complex. To examine somatotopic organization, we separately stimulated the left and right hand and foot. No spatial segregation between hand and foot responses was observed in MST. The average response profile of MST was similar to that of somatosensory cortex, with a strong preference for the contralateral hand. These results offer evidence for the existence of somatosensory responses in MST, but not MT, independent of imagery of visual motion.
先前关于人类视觉区域MT/V5触觉反应的报告使用了复杂刺激，比如用刷子轻刷手臂。这些复杂的移动刺激很可能诱发视觉运动的意象，而视觉运动已知是MT的一种强大激活因素。先前报告中描述为“MT”的区域至少由两个不同的皮质区域组成，即MT和MST。我们利用功能磁共振成像分别对人类的MT和MST进行定位，并测量它们对不太可能诱发视觉运动意象的振动触觉刺激的反应。在MST中观察到了强烈的振动触觉反应，但在MT中未观察到。MST中的振动触觉反应约为对视觉运动反应的一半，且与先前报告的另一个对触觉刺激有反应的视觉区域——枕外侧复合体中的反应不同。为了研究躯体定位组织，我们分别刺激左手、右手、左脚和右脚。在MST中未观察到手部和足部反应之间的空间分隔。MST的平均反应模式与躯体感觉皮层相似，对侧手的偏好很强。这些结果为MST中存在独立于视觉运动意象的躯体感觉反应提供了证据，但MT中不存在这种反应。
