Effects of early monocular eyelid suture upon development of relay cell classes in the cat's lateral geniculate nucleus
Authors: Lin Chia‐Sheng , Murray Sherman S. 
Published: January 2005

Horseradish peroxidase (HRP) was injected into visual cortex of four normal cats and five cats raised with monocular lid suture, and retrograde labelling was assessed in cells of the lateral geniculate nucleus. In all but one of the sutured cats (noted below) focal injections were carefully limited to area 17 or 18 and analysis of labelling focused on laminae A and A1. The effects of deprivation were indistinguishable whether lamina A or A1 was deprived, and in all cases, the nondeprived laminae had labelling essentially identical to that seen in normal cats.

After area 17 injections (bilateral in one normal cat and unilateral in 3 deprived cats), roughly 77% of the cells in nondeprived laminae were labelled and they were mostly small to medium in size. Deprived laminae, when compared to nondeprived laminae, had two abnormalities: (1) cells, both labelled and unlabelled, were smaller; and (2) roughly 11% fewer cells (i.e., 66%) were labelled, and this represents a small but statistically significant difference for each cat. After area 18 injections (bilateral in one normal cat plus unilateral in 3 other normal and 3 deprived cats), roughly 15% of the cells in nondeprived laminae were labelled, and they tended to be large in size. Deprived laminae, when compared to nondeprived laminae, had three abnormalities: (1) only 5–6% of the cells were labelled, and these tended to be quite faintly labelled; (2) the volume occupied by labelled cells was small; and (3) both labelled and unlabelled cells were reduced in size. Finally, large bilateral injections were made throughout occipitotemporal cortex in one lid sutured cat in an effort to label completely the terminal zones of cells in the medial interlaminar nucleus (MIN), a division of the lateral geniculate nucleus; this cat also had a prior intraocular injection of tritiated proline to provide through subsequent autoradiography a delineation of deprived and nondeprived portions of MIN. Roughly 78% of the cells in nondeprived portions of MIN were labelled in this cat. In the deprived portions, only about 51% of the cells were labelled, and these tended to be faintly labelled. Also, labelled cells were smaller, and unlabelled cells were larger in deprived than they were in nondeprived portions.

Since prior studies have shown that, within the A laminae, X‐cells project exclusively to area 17 whereas the Y‐cell population projects to areas 17 and 18, these data are taken as further support of the conclusion that geniculate Y‐cells are more seriously affected by the early deprivation than are geniculate X‐cell. That is, these data are consistent with the suggestion that a similar population of Y‐cells in deprived laminae (roughly 10% of the overall cell total) fail to transport HRP from area 17 or area 18 injections. This can be extended to the MIN, which seems to be comprised nearly exclusively of Y‐cells. However, these conclusions must be considered tentative, since interpretation of HRP data can be difficult as evidenced by discrepancies in the literature.