Swindale N V
Physiological Laboratory, Cambridge, England.
J Comp Neurol. 1988 Jan 22;267(4):472-88. doi: 10.1002/cne.902670403.
Transneuronal autoradiography was used to study the role of visual experience in the development of ocular dominance patches in the cat. In order to assess quantitatively the effects of visual deprivation, image analysis was used to measure the profiles of grain density in layer IV. Fourier power spectra of these profiles were computed to give a measure of the amplitudes and frequencies of the fluctuations in grain density that were present. Deprivation of normal patterned vision by binocular lid suture or by rearing in total darkness from shortly after birth abolished the dominant periodicity (of about 1.1 mm) in the distribution of left and right eye afferents in layer IV of area 17. A dominant periodicity of about 2.2 mm was, however, present in area 18 of both normal and dark-reared animals. Visual deprivation was not able to reverse segregation. One animal reared normally for 6 weeks was placed in the dark for a further 28 weeks and showed normal periodicities in the distribution of geniculate inputs to area 17. Another animal given 128 hours of experience and kept in the dark for the rest of the time until it was 12 weeks old also showed normal segregation. To determine the minimum amount of visual experience necessary for segregation to occur, four animals were given 8-, 24-, 48-, and 128-hour periods of visual experience and were studied at 12 weeks of age. Eight hours of experience had no detectable effect on segregation; periodicities of intermediate amplitude were present in animals that received 24 and 48 hours of experience, while 128 hours of experience resulted in periodicities of normal amplitude. Recovery from visual deprivation was studied by rearing kittens from birth in the dark for varying periods and then returning them to the normally lit colony room for periods of 6 to 22 weeks. Recovery from 6 weeks of dark rearing was found to be complete; much less recovery occurred following periods of 8 to 25 weeks of initial deprivation, and no recovery at all occurred after 30 weeks of deprivation. It is concluded that the spontaneous activity present in the geniculocortical afferents of dark-reared and lid-sutured cats is not adequate to drive normal periodic segregation in area 17, though it can do so in area 18. Between 48 and 128 hours of visual experience, given before 8 weeks of age, appears to be necessary and sufficient for normal periodic segregation of geniculate afferents in area 17 of the cat.
跨神经元放射自显影术被用于研究视觉经验在猫视皮层眼优势柱发育中的作用。为了定量评估视觉剥夺的影响，采用图像分析来测量IV层的颗粒密度分布。计算这些分布的傅里叶功率谱，以衡量颗粒密度波动的幅度和频率。通过双眼睑缝合或从出生后不久就在完全黑暗中饲养来剥夺正常的模式视觉，消除了17区IV层左右眼传入纤维分布中的主导周期性（约1.1毫米）。然而，在正常饲养和黑暗饲养的动物的18区中都存在约2.2毫米的主导周期性。视觉剥夺并不能逆转分离现象。一只正常饲养6周的动物再在黑暗中饲养28周，其外侧膝状体输入到17区的分布显示出正常的周期性。另一只动物有128小时的视觉经验，其余时间都饲养在黑暗中，直到12周龄时也显示出正常的分离现象。为了确定发生分离所需的最小视觉经验量，对四只动物分别给予8小时、24小时、48小时和128小时的视觉经验，并在12周龄时进行研究。8小时的经验对分离没有可检测到的影响；接受24小时和48小时经验的动物中存在中等幅度的周期性，而128小时的经验导致正常幅度的周期性。通过将小猫从出生开始在黑暗中饲养不同时间段，然后将它们放回正常光照的群体饲养室6至22周，来研究从视觉剥夺中恢复的情况。发现从6周黑暗饲养中恢复是完全的；在最初剥夺8至25周后恢复程度要小得多，而在剥夺30周后则完全没有恢复。结论是，黑暗饲养和眼睑缝合的猫的外侧膝状体 - 皮层传入纤维中存在的自发活动不足以驱动17区正常的周期性分离，尽管它可以在18区做到这一点。在8周龄之前给予48至128小时的视觉经验，似乎是猫17区外侧膝状体传入纤维正常周期性分离所必需且充分的。
