Wang Gang, Ding Shan, Yunokuchi Kazutomo
Department of Bioengineering, Faculty of Engineering, Kagoshima University, Kagoshima 890-0065, USA.
J Neurophysiol. 2003 Dec;90(6):3912-20. doi: 10.1152/jn.00219.2003. Epub 2003 Aug 20.
Extensive attempts have been made to explain the neurobiological basis of the greater sensitivity of the visual system to vertically or horizontally oriented information than to information presented at oblique angles. However, investigators have largely ignored the overlap of the representation of a given angle with the representation of nearby angles. Recordings based on intrinsic optical signals were obtained in area 17 from 12 adult cats during the presentation of contours in various orientations. A method investigating both amplitude and statistical significance of changes was proposed to evaluate the orientation tuning properties for cell populations in the central area retinotopically corresponding to 0-15 degrees of visual field. Cardinal orientations were found to activate significantly greater areas in the exposed cortical area than the areas activated by oblique orientations. Areas activated by cardinal or oblique contours and those separated from them by 10 degrees were compared. A significantly lower degree of overlap was seen between areas activated by presentation of cardinal contours and areas activated by neighboring orientations compared with those for oblique orientations which overlapped more extensively with neighboring orientations. In addition, areas activated only by cardinal contours were significantly larger than areas activated only by oblique contours. These results demonstrated in cell population level that more cells prefer horizontal or vertical orientations, and these cells are tuned more sharply than oblique selective cells.
人们已经进行了大量尝试来解释视觉系统对垂直或水平方向信息的敏感性高于对以斜角呈现的信息的敏感性的神经生物学基础。然而，研究人员在很大程度上忽略了给定角度的表征与附近角度的表征之间的重叠。在12只成年猫的17区，在呈现各种方向的轮廓时，基于内在光学信号进行了记录。提出了一种研究变化的幅度和统计显著性的方法，以评估在视网膜拓扑上对应于视野0-15度的中央区域中细胞群体的方向调谐特性。发现主要方向在暴露的皮质区域中激活的区域明显大于斜向方向激活的区域。比较了由主要轮廓或斜向轮廓激活的区域以及与它们相隔10度的区域。与斜向轮廓相比，主要轮廓激活的区域与相邻方向激活的区域之间的重叠程度明显更低，斜向轮廓与相邻方向的重叠更为广泛。此外，仅由主要轮廓激活的区域明显大于仅由斜向轮廓激活的区域。这些结果在细胞群体水平上表明，更多的细胞更喜欢水平或垂直方向，并且这些细胞比斜向选择性细胞的调谐更尖锐。
