Di Russo Francesco, Pitzalis Sabrina, Aprile Teresa, Spitoni Grazia, Patria Fabiana, Stella Alessandra, Spinelli Donatella, Hillyard Steven A
Department of Education in Sports and Human Movement, University of Motor Sciences (IUSM), Rome, Italy.
Hum Brain Mapp. 2007 Apr;28(4):323-34. doi: 10.1002/hbm.20276.
This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874-886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing.
本研究旨在表征对重复的6Hz模式反转刺激产生的稳态视觉诱发电位（SSVEP）的神经发生器。将SSVEPs的多通道头皮记录和偶极子建模技术与功能磁共振成像（fMRI）和视网膜定位映射相结合，以估计由模式反转诱发的SSVEP的皮层源位置。随时间变化的SSVEP头皮地形图表明有两个主要皮层源的贡献，它们分别位于对侧半球的枕叶内侧和颞叶中部区域。偶极子位置与fMRI激活位点的共定位表明，SSVEP的这两个主要源分别位于初级视觉皮层（V1）和运动敏感区（MT/V5）。还考虑了枕叶中部（V3A）和枕叶腹侧（V4/V8）区域的较小贡献。将SSVEP相位信息与先前一项瞬态VEP研究（Di Russo等人，[2005]《神经影像学》24:874 - 886）中收集的时间信息进行比较，结果表明，稳态刺激和瞬态刺激的皮层激活顺序相似。这些结果提供了SSVEP皮层起源的详细时空概况，这应会增强其作为评估视觉皮层功能障碍的有效临床工具以及视觉感知处理皮层机制研究探针的用途。
