Melzer P, Welker E, Dörfl J, Van der Loos H
Institute of Anatomy, University of Lausanne, Switzerland.
Brain Res Dev Brain Res. 1994 Feb 18;77(2):227-50. doi: 10.1016/0165-3806(94)90199-6.
We examined functional maturation in the mouse whisker-to-barrel pathway from P2 (P0 is the day of birth) to adulthood using the autoradiographic deoxyglucose (DG) method. After intraperitoneal DG injection, left whiskers C1-3 and E1 were stimulated. Sections were cut transversely through the brainstem, and coronally or tangentially through the parietal cortex. After autoradiography, the sections were stained for Nissl or for cytochrome oxidase (CO) activity. In subnuclei caudalis and interpolaris of the spinal trigeminal nucleus ipsilateral to stimulation, DG uptake evoked by the deflection of whiskers C1-3 was present at P2; in subnucleus oralis, nucleus principalis and the contralateral nucleus ventrobasalis of the thalamus, at P4; and in the contralateral barrel cortex, at P7. The first stimulus-dependent DG uptake appeared a few days after the appearance of whisker-related patterns seen in the CO- or Nissl-stained sections. In subnuclei caudalis and interpolaris, areas of stimulus-dependent DG uptake were initially larger than the CO segments representing the stimulated whiskers. Later, areas of stimulus-dependent DG uptake and CO segments matched well. DG uptake evoked by the stimulation of whisker E1 appeared 2-3 days later than that evoked by stimulation of whiskers C1-3. In nucleus principalis, one large area of stimulus-dependent DG uptake covered the representations of the caudal whiskers of all five rows--an observation made at all ages studied. In thalamus, stimulus-dependent DG uptake was found laterally in nucleus ventrobasalis. In barrel cortex, at P7, stimulus-dependent DG uptake was restricted to layers III and IV, but covered more barrels than whiskers stimulated. At P9, a second spot of high DG uptake was seen in deep layer V in register with that in layers III and IV. From P10 onwards, stimulus-dependent DG uptake stretched from layer II to layer VI, and in layer IV, in which it was highest, it was restricted to the barrels C1-3 and E1. In all stations, stimulus-dependent DG uptake decreased in magnitude after P10. While the onset of stimulus-dependent DG uptake is the result of the establishment of functional projections up to that station, the subsequent changes in size of the responding areas may well be due to the partial elimination of terminals, the maturation of local inhibitory circuits, and/or the development of cortical projections to the nuclei of termination and to the thalamic relay.
我们使用放射自显影脱氧葡萄糖（DG）方法，研究了从出生后第2天（P0为出生日）到成年期小鼠触须到桶状皮层通路的功能成熟情况。腹腔注射DG后，刺激左侧触须C1 - 3和E1。将脑干横向切片，将顶叶皮层冠状或切向切片。放射自显影后，切片进行尼氏染色或细胞色素氧化酶（CO）活性染色。在刺激同侧的三叉神经脊束核尾侧亚核和极间亚核中，触须C1 - 3偏转引起的DG摄取在P2时出现；在口侧亚核、主核和对侧丘脑腹后核中，在P4时出现；在对侧桶状皮层中，在P7时出现。第一次刺激依赖性DG摄取出现在CO或尼氏染色切片中可见的触须相关模式出现几天后。在尾侧亚核和极间亚核中，刺激依赖性DG摄取区域最初大于代表受刺激触须的CO节段。后来，刺激依赖性DG摄取区域与CO节段很好地匹配。触须E1刺激引起的DG摄取比触须C1 - 3刺激引起的DG摄取晚2 - 3天出现。在主核中，一个大的刺激依赖性DG摄取区域覆盖了所有五排尾侧触须的代表区——这一观察结果在所有研究的年龄段都有。在丘脑中，刺激依赖性DG摄取在腹后核外侧被发现。在桶状皮层中，在P7时，刺激依赖性DG摄取局限于III层和IV层，但覆盖的桶比受刺激的触须多。在P9时，在V层深部发现第二个高DG摄取点，与III层和IV层的点对齐。从P10开始，刺激依赖性DG摄取从II层延伸到VI层，在摄取最高的IV层，它局限于C1 - 3和E1桶。在所有部位，P10后刺激依赖性DG摄取量下降。虽然刺激依赖性DG摄取的开始是到该部位的功能投射建立的结果，但随后反应区域大小的变化很可能是由于终末的部分消除、局部抑制回路的成熟和/或向终末核和丘脑中继核的皮质投射的发育。
