Blasdel G, Obermayer K, Kiorpes L
Department of Physiology, University of Calgary, Alberta, Canada.
Vis Neurosci. 1995 May-Jun;12(3):589-603. doi: 10.1017/s0952523800008476.
Previous work has shown that small, stimulus-dependent changes in light absorption can be used to monitor cortical activity, and to provide detailed maps of ocular dominance and optimal stimulus orientation in the striate cortex of adult macaque monkeys (Blasdel & Salama, 1986; Ts'o et al., 1990). We now extend this approach to infant animals, in which we find many of the organizational features described previously in adults, including patch-like linear zones, singularities, and fractures (Blasdel, 1992b), in animals as young as 3 1/2 weeks of age. Indeed, the similarities between infant and adult patterns are more compelling than expected. Patterns of ocular dominance and orientation, for example, show many of the correlations described previously in adults, including a tendency for orientation specificity to decrease in the centers of ocular dominance columns, and for iso-orientation contours to cross the borders of ocular dominance columns at angles of 90 deg. In spite of these similarities, there are differences, one of which entails the strength of ocular dominance signals, which appear weaker in the younger animals and which increase steadily with age. Another, more striking, difference concerns the widths of ocular dominance columns, which increase by 20% during the first 3 months of life. Since the cortical surface area increases by a comparable amount, during the same time, this 20% expansion implies that growth occurs anisotropically, perpendicular to the ocular dominance columns, as the cortical surface expands. Since the observed patterns of orientation preference expand more slowly, at approximately half this rate, these results also imply that ocular dominance and orientation patterns change their relationship, and may even drift past one another, as young animals mature.
先前的研究表明，光吸收中与刺激相关的微小变化可用于监测皮层活动，并绘制成年猕猴纹状皮层中眼优势和最佳刺激方向的详细图谱（布拉斯德尔和萨拉马，1986年；曹等人，1990年）。我们现在将这种方法扩展到幼小动物身上，发现3.5周龄的幼小动物就具备了许多先前在成年动物中描述的组织特征，包括斑块状线性区域、奇点和裂缝（布拉斯德尔，1992b）。事实上，幼年和成年模式之间的相似性比预期的更引人注目。例如，眼优势和方向模式显示出许多先前在成年动物中描述的相关性，包括在眼优势柱中心方向特异性降低的趋势，以及等方向轮廓以90度角穿过眼优势柱边界的趋势。尽管存在这些相似性，但也存在差异，其中之一涉及眼优势信号的强度，在幼小动物中眼优势信号显得较弱，并随年龄稳步增加。另一个更显著的差异涉及眼优势柱的宽度，在生命的前3个月中增加了20%。由于同期皮层表面积增加了相当的量，这种20%的扩张意味着随着皮层表面扩张，生长是各向异性的，垂直于眼优势柱。由于观察到的方向偏好模式扩张得更慢，大约是这个速度的一半，这些结果还意味着随着幼小动物成熟，眼优势和方向模式会改变它们之间的关系，甚至可能相互漂移。
