Tommerdahl M, Favorov O, Whitsel B L, Nakhle B, Gonchar Y A
Department of Biomedical Engineering, University of North Carolina, Chapel Hill 27599.
Cereb Cortex. 1993 Sep-Oct;3(5):399-411. doi: 10.1093/cercor/3.5.399.
The distribution of stimulus-evoked 14C-2-deoxyglucose (2DG) labeling in primary somatosensory cortex (SI) of monkey (Macaca fascicularis) and cat was investigated. Reconstructions of the global pattern of labeling reveal that discrete skin stimuli evoke activity within an extensive region of SI, and that the activation pattern typically consists of multiple, elongated regions of above-background labeling ("modules," typically 0.5-1.0 mm wide, and 1-4 mm long). Evidence obtained using recently developed methods (Tommerdahl, 1989) for quantitative analysis of 2DG activity patterns is shown to be consistent with the idea (Whitsel et al., 1991) that SI modules typically are bounded by zones dominated by stimulus-evoked inhibition. The labeling pattern within individual 2DG modules in SI of both cats and monkeys is analyzed quantitatively (in the frequency domain). Within-module spatial activation patterns are demonstrated to be periodic, consisting of radially oriented profiles of above-background labeling separated from each other by less strongly labeled radial profiles. The spectral characteristics of within-module 2DG labeling change systematically with location along the module's long axis: spatial frequencies between 18 and 35 cycles/mm are prominent in the labeling that occupies both the middle and upper layers at central locations in the module, but are a less obvious component of the labeling in both the middle and upper layers at locations remote to the module center. Since the radially oriented periodic variation both (1) in 2DG labeling in regions of SI outside modules and (2) in optical density in images of Nissl-stained sections of SI consists predominantly of spatial frequencies in the range of 18-35 cycles/mm, it is concluded that the radial profiles of labeling within individual 2DG modules correspond to groupings of minicolumns distinguishable from their neighbors on the basis of labeling intensity. The findings raise the possibility that highly structured, within-module spatial patterns of SI minicolumnar activation encode information about the physical properties of tactile stimuli.
研究了刺激诱发的14C - 2 - 脱氧葡萄糖（2DG）标记在猕猴（食蟹猴）和猫的初级体感皮层（SI）中的分布。对标记的整体模式进行重建后发现，离散的皮肤刺激会在SI的广泛区域内引发活动，并且激活模式通常由多个高于背景标记的细长区域组成（“模块”，通常宽0.5 - 1.0毫米，长1 - 4毫米）。使用最近开发的方法（Tommerdahl，1989）对2DG活动模式进行定量分析所获得的证据表明，与SI模块通常由刺激诱发抑制主导的区域所界定这一观点（Whitsel等人，1991）一致。对猫和猕猴的SI中单个2DG模块内的标记模式进行了定量分析（在频域中）。模块内的空间激活模式被证明是周期性的，由高于背景标记的径向分布组成，这些分布彼此之间由标记较弱的径向分布隔开。模块内2DG标记的光谱特征会沿着模块的长轴位置系统地变化：在模块中心位置占据中层和上层的标记中，18至35周期/毫米之间的空间频率很突出，但在远离模块中心的位置，中层和上层的标记中该频率成分则不太明显。由于（1）SI模块外区域的2DG标记以及（2）SI的尼氏染色切片图像中的光密度的径向定向周期性变化主要由18 - 35周期/毫米范围内的空间频率组成，因此得出结论，单个2DG模块内的标记径向分布对应于基于标记强度可与相邻者区分开的小柱分组。这些发现提出了一种可能性，即SI小柱激活的高度结构化的模块内空间模式编码了有关触觉刺激物理特性的信息。
