Cornette L, Dupont P, Spileers W, Sunaert S, Michiels J, Van Hecke P, Mortelmans L, Orban G A
Laboratorium voor Neuro- en Psychofysiologie, KU Leuven, Medical School, Belgium.
Brain. 1998 Jan;121 ( Pt 1):143-57. doi: 10.1093/brain/121.1.143.
In this PET study, we have investigated the human brain activity evoked by a visual motion paradigm commonly used to measure motion-related visual evoked potentials (VEPs). Because standard PET activation studies have been performed with motion along four axes, we first determined the pattern of brain activation when motion was restricted to a single axis. Motion back and forward along a single horizontal axis compared with a static condition revealed weak differential activations in the cuneus and the parietal cortex. Human area MT/V5 (middle temporal area) was hardly activated at all in this subtraction. Additional functional MRI experiments proved that MT/V5 activity is significantly higher for motion along four axes than for motion along a single axis. Secondly, we attempted to isolate the pattern of brain activity related to the reversal of motion direction and to the onset of motion, i.e. two transient motion components commonly used in measuring motion-related VEPs. To that end, we added a continuous linear contrast modulation, that reached maximum contrast at reversal or onset of motion, and compared both conditions with a contrast-modulated static or continuous motion condition. Subtraction of the static random dot pattern condition from the single-axis motion reversal condition, both contrast-modulated, revealed three significant activations: the anterior parieto-occipital sulcus, the lateral sulcus and the anterior claustrum. Additional analysis showed that these activations were not due to motion appearance or disappearance, but were due to the combination of motion reversal and contrast modulation. Hence, these activations do not reflect the motion reversal transient per se. In order to isolate a metabolic response to the reversal transient per se, we used a conjunction analysis, which suggests that activity in human MT/V5, the cuneus and a parietal insular region could underlie the motion reversal VEP in our experiments. Subtraction of the static random dot pattern condition from the single-axis motion onset condition, both contrast-modulated, revealed a single significant activation in the posterior cingulate cortex. Although the significance of this activation is unclear, it adds further evidence for the visual function of this region.
在这项正电子发射断层扫描（PET）研究中，我们调查了由一种常用于测量与运动相关的视觉诱发电位（VEP）的视觉运动范式所诱发的人脑活动。由于标准的PET激活研究是沿着四个轴进行运动的，我们首先确定了运动限制在单个轴上时的脑激活模式。与静态条件相比，沿着单个水平轴前后运动在楔叶和顶叶皮层显示出微弱的差异激活。在这种减法运算中，人类的MT/V5区（颞中区）几乎未被激活。额外的功能磁共振成像（fMRI）实验证明，沿着四个轴运动时MT/V5区的活动明显高于沿着单个轴运动时的活动。其次，我们试图分离与运动方向反转和运动起始相关的脑活动模式，即测量与运动相关的VEP时常用的两个瞬态运动成分。为此，我们添加了一种连续的线性对比度调制，该调制在运动反转或起始时达到最大对比度，并将这两种条件与对比度调制的静态或连续运动条件进行比较。从单轴运动反转条件（两者均为对比度调制）中减去静态随机点模式条件，揭示出三个显著激活区域：顶枕前沟、外侧沟和前屏状核。进一步分析表明，这些激活并非由于运动的出现或消失，而是由于运动反转和对比度调制的组合。因此，这些激活并不反映运动反转瞬态本身。为了分离对反转瞬态本身的代谢反应，我们使用了联合分析，这表明在我们的实验中，人类MT/V5区、楔叶和顶叶岛叶区域的活动可能是运动反转VEP的基础。从单轴运动起始条件（两者均为对比度调制）中减去静态随机点模式条件，在后扣带回皮层发现了一个显著激活。尽管这种激活的意义尚不清楚，但它进一步证明了该区域的视觉功能。
