Precision and variability of hindlimb representation in cat dorsal horn and implications for tactile localization.
Precision and variability of hindlimb representation in cat dorsal horn and implications for tactile localization.
复制标题
猫背角后肢表征的精度和变异性以及对触觉定位的影响。
DOI：
10.1152/jn.1993.70.6.2489
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发表时间：
1993
影响因子：
2.5
通讯作者：
Brown,PB
中科院分区：
文献类型：
--
作者：
Koerber,HR;Hobbs,G;Brown,PB
1.在6只麻醉猫的L5-S1节段的节段边界和中段，记录了158个细胞在细胞外跨越左右背角的一排排轨迹。对于每个细胞的低阈值皮肤机械感受野确定与使用手持探头，并记录网站标记有一个微损伤。重建记录位点，并记录每个细胞的内外侧（ML）和吻尾侧（RC）位置沿着细胞感受野的位置，表示为距脚趾尖的距离（D）。2.在同一只动物的双侧对称位置（+/- 10%）记录到的细胞对中，95%的细胞对在对侧腿上具有镜像对称的感受野。只有42%的细胞对偏离双边对称约+/- 240微米的感受野重叠的组件。这表明，有一个实质性的双边对称性，这不仅仅是由于大的感受野。3.在一个单一的轨道行中的细胞的感受野的轨迹绘制的顺序，从内侧到外侧记录网站，结合两侧。这些轨迹在腿上遵循远近端路线。在用于绘制这些轨迹的144个相邻细胞中，平均间距约为120 μ m，在动物体内仅观察到6次远端近端梯度极性反转。4.将来自个体动物的数据向吻侧和尾侧移动，以获得与样本中其他动物的组合数据的中外侧躯体位置梯度的最佳一致性。最佳的协议是从0.3节段头侧到0.4节段尾侧，平均绝对值移动0.22节段。5.通过比较同一背角内、同一动物的相对侧以及不同动物之间的细胞对，可以计算出给定平均图和感受野的细胞位置的变异性。动物间变异性和双侧不对称性约为+/- 60微米，背角内变异性约为+/- 35微米。动物间变异性相当于腿上远端近端感受野位置的变异性为+/-13 mm，高放大率区域的变异性较小（例如，脚趾），以及在具有小放大率的区域中的较大可变性（例如，大腿）。这种变异程度与背柱横断动物以正常精确度定位触觉刺激的能力一致。
1. One hundred fifty-eight cells were recorded extracellularly in rows of tracks spanning both left and right dorsal horns, at segmental boundaries and midsegment in segments L5-S1, in six anesthetized cats. For each cell the low-threshold cutaneous mechano-receptive field was determined with the use of hand-held probes, and the recording site was marked with a microlesion. Recording sites were reconstructed, and the mediolateral (ML) and rostrocaudal (RC) locations of each cell were recorded along with the location of the cell's receptive field, expressed as distance from tips of toes (D). 2. Ninety-five percent of pairs of cells recorded from bilaterally symmetric locations (+/- 10%) in the same animal had receptive fields on opposite legs that had components that were mirror symmetric. Only 42% of cell pairs deviating from bilateral symmetry by approximately +/- 240 microns had receptive fields with overlapping components. This indicated that there was a substantial bilateral symmetry that was not simply due to large receptive fields. 3. The trajectories of receptive fields of cells in a single row of tracks were plotted in order of mediolateral recording site, going from medial to lateral, combining both sides. These trajectories followed a distoproximal course on the leg. Of 144 adjacent cells used to plot these trajectories, with an average spacing of approximately 120 microns, only 6 reversals of the distoproximal gradient polarity were observed within animals. 4. Data from individual animals were shifted rostrally and caudally, to obtain best agreement of mediolateral somatotopic gradients with the combined data from the other animals in the sample. Best agreement was obtained with shifts ranging from 0.3 segment rostral to 0.4 segment caudal, with an average absolute value shift of 0.22 segment. 5. By comparing cell pairs within the same dorsal horn, on opposite sides of the same animal, and across animals, variability in cell placement given the average map and the receptive field could be calculated. Interanimal variability and bilateral asymmetry were approximately +/- 60 microns, and within-dorsal horn variability was approximately +/- 35 microns. The interanimal variability is equivalent to a variability of distoproximal receptive-field location on the leg of +/- 13 mm, with a smaller variability in areas of high magnification (e.g., the toes), and a larger variability in areas with small magnification (e.g., the thigh). This degree of variability is consistent with the ability of animals with transected dorsal columns to localize tactile stimuli with a normal degree of precision.