ISSN:
1432-1106
Keywords:
Cat LGN
;
Monocular Deprivation
;
Visual Acuity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The visual acuity (spatial resolving power) and the relative incidence of X- and Y-cells in laminae A and A1 of the dorsal lateral geniculate nucleus (LGN) with receptive fields within 10 ° visual angle to the area centralis have been determined in normal and monocularly deprived cats, using a square-wave grating with logarithmically varying spatial frequencies (0.05–8 c/deg). In the normal cat's LGN the incidence of Y-cells is 1.6 times higher in A1 (48% of the relay-cells) than in A (29%). The mean spatial resolution of all cells is 1.3 times higher in A (2.5 ± 1.2 c/deg) than in A1 (1.8 ± 1.0 c/deg). Mean acuity of Y-cells is equal in both laminae (1.1 ± 0.5 c/deg), but for X-cells it is higher in lamina A (2.9 ± 1.0 c/deg in A, vs. 2.5 ± 0.7 c/deg in A1). After early monocular deprivation, visual acuity is reduced in the deprived lamina A1 (X-cells: 1.7 ± 0.9 c/deg in A1 vs. 2.6 ± 0.7 c/deg in A; Y-cells: 0.9 ± 0.4 c/deg in A1 vs. 1.3 ± 0.4 c/deg in A). This confirms the results of Maffei and Fiorentini (1976). However, visual acuity of X-cells is still higher in the deprived lamina A (3.1 ± 1.0 c/deg) than in the non-deprived lamina A1 (2.7 ± 0.7 c/deg). For Y-cells, visual acuity is equal in both laminae (1.3 ± 0.5 c/deg). Thus the loss of visual acuity is only significant in lamina A1. This loss was equally strong in the area centralis and up to 10 ° eccentricity. Ipsilateral to the early deprived eye only 37% of all recorded Y-cells were located in the deprived lamina A1 (this is 1.7 times less than in the normal A1). Contralateral to the deprived eye 29% of the Y-cells were recorded in the deprived lamina A (1.3 times less than in the normal A). In conclusion, both the impairment of mean visual acuity and the reduction in the recording probability of Y-cells were more pronounced in lamina A1 (receiving uncrossed inputs from the deprived eye) than in lamina A (crossed inputs).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00239151
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