Koralek K A, Killackey H P
Department of Psychobiology, University of California, Irvine 92717.
Proc Natl Acad Sci U S A. 1990 Feb;87(4):1396-400. doi: 10.1073/pnas.87.4.1396.
During the first postnatal week, the distribution of callosal projection neurons in the rat somatosensory cortex changes from a uniform to a discontinuous pattern. To determine if this change is influenced by afferent inputs to the somatosensory cortex, the effect of both early unilateral infraorbital nerve section and unilateral removal of the dorsal thalamus on the distribution of callosal projections in rat somatosensory cortex was examined. One month after either of the above manipulations at birth, the tangential distribution of callosal projections in the somatosensory cortex was examined using the combined retrograde and anterograde transport of horseradish peroxidase. Both manipulations alter the distribution of callosal projection neurons and terminations in the somatosensory cortex. After infraorbital nerve section, the distribution of callosal projections is altered in the contralateral primary somatosensory cortex. The abnormalities observed are consistent with the altered distribution of thalamocortical projections. In addition, consistent abnormalities were observed in the pattern of callosal projections of the second somatosensory area of both hemispheres. Most notably, they are absent in a portion of the region that contains the representation of the mystacial vibrissae and sinus hairs in this area. Thalamic ablation resulted in highly aberrant patterns of callosal projections in the somatosensory cortex on the operated side, where abnormal bands and clusters of callosal projections were observed in apparently random locations. These results are interpreted as evidence that both peripheral and central inputs influence the maturational changes in the distribution of callosal projection neurons.
在出生后的第一周，大鼠体感皮层中胼胝体投射神经元的分布从均匀模式转变为不连续模式。为了确定这种变化是否受体感皮层传入输入的影响，研究了早期单侧眶下神经切断和单侧丘脑背侧切除对大鼠体感皮层胼胝体投射分布的影响。在出生时进行上述任何一种操作后的一个月，使用辣根过氧化物酶的逆行和顺行联合转运来检查体感皮层中胼胝体投射的切线分布。两种操作均改变了体感皮层中胼胝体投射神经元和终末的分布。眶下神经切断后，对侧初级体感皮层中胼胝体投射的分布发生改变。观察到的异常与丘脑皮质投射的改变分布一致。此外，在两个半球的第二体感区的胼胝体投射模式中也观察到了一致的异常。最值得注意的是，在该区域中包含触须和鼻窦毛表征的部分区域中没有胼胝体投射。丘脑切除导致手术侧体感皮层中胼胝体投射的高度异常模式，在明显随机的位置观察到胼胝体投射的异常带和簇。这些结果被解释为外周和中枢输入均影响胼胝体投射神经元分布成熟变化的证据。
