Heider Barbara, Siegel Ralph M
Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ, 07102, USA,
Brain Struct Funct. 2014 Mar;219(2):495-509. doi: 10.1007/s00429-013-0513-y. Epub 2013 Feb 8.
Sensorimotor transformation for reaching movements in primates requires a large network of visual, parietal, and frontal cortical areas. We performed intrinsic optical imaging over posterior parietal cortex including areas 7a and the dorsal perilunate in macaque monkeys during visually guided hand movements. Reaching was performed while foveating one of nine static reach targets; thus eye-position-varied concurrently with reach position. The hemodynamic reflectance signal was analyzed during specific phases of the task including pre-reach, reach, and touch epochs. The eye position maps changed substantially as the task progressed: First, direction of spatial tuning shifted from a weak preference close to the center to the lower eye positions in both cortical areas. Overall tuning strength was greater in area 7a. Second, strength of spatial tuning increased from the early pre-reach to the later touch epoch. These consistent temporal changes suggest that dynamic properties of the reflectance signal were modulated by task parameters. The peak amplitude and peak delay of the reflectance signal showed considerable differences between eye position but were similar between areas. Compared with a detection task using a lever response, the reach task yielded higher amplitudes and longer delays. These findings demonstrate a spatially tuned topographical representation for reaching in both areas and suggest a strong synergistic combination of various feedback signals that result in a spatially tuned amplification of the hemodynamic response in posterior parietal cortex.
灵长类动物伸手动作的感觉运动转换需要一个由视觉、顶叶和额叶皮质区域组成的庞大网络。我们在猕猴进行视觉引导的手部动作时，对包括7a区和背侧月状沟周围区域在内的后顶叶皮质进行了内在光学成像。在注视九个静态伸手目标之一的同时进行伸手动作；因此，眼睛位置与伸手位置同时变化。在任务的特定阶段，包括伸手前、伸手和触摸阶段分析血流动力学反射信号。随着任务的进行，眼睛位置图发生了显著变化：首先，在两个皮质区域中，空间调谐方向从靠近中心的微弱偏好转移到较低的眼睛位置。7a区的整体调谐强度更大。其次，空间调谐强度从伸手前早期到触摸后期增加。这些一致的时间变化表明，反射信号的动态特性受任务参数调制。反射信号的峰值幅度和峰值延迟在眼睛位置之间存在显著差异，但在区域之间相似。与使用杠杆反应的检测任务相比，伸手任务产生更高的幅度和更长的延迟。这些发现表明，在这两个区域中存在用于伸手动作的空间调谐地形图表示，并表明各种反馈信号的强烈协同组合导致后顶叶皮质中血流动力学反应的空间调谐放大。
