Komenda J K, Fite K V
Behav Neurosci. 1983 Dec;97(6):928-36. doi: 10.1037//0735-7044.97.6.928.
Optokinetic nystagmus (OKN) was studied in both normally pigmented and delayed amelanotic (DAM) strains of domestic chicken. The DAM line is characterized by postnatal feather and ocular depigmentation accompanied by progressive retinal degeneration that occurs, initially and most severely, in the central retina. A close association exists between the extent of ocular pigment loss and relative reduction in OKN responsiveness in DAMs. The directional asymmetry of OKN responses, which normally occurs with monocular temporal-to-nasal (T-N) but not to nasal-to-temporal (N-T) stimulation, was altered in relation to the extent of ocular amelanosis among DAMs. In particular, T-N OKN responses were progressively reduced as amelanosis of the central retina increased in severity. In DAMs with moderate to severe reductions in T-N responsiveness, relatively little reduction occurred in N-T responsiveness. The central retina, therefore, appears to play a major role in mediating responses to T-N stimulation, whereas the peripheral retina mediates both directions of response. Optokinetic nystagmus also provides a useful index of the extent of retinal degeneration and the progressive loss of retinal pigment epithelium and photoreceptors which occurs in this mutant strain.
在家鸡的正常色素沉着和延迟无黑色素（DAM）品系中研究了视动性眼震（OKN）。DAM品系的特征是出生后羽毛和眼部色素脱失，伴有进行性视网膜变性，最初且最严重地发生在中央视网膜。在DAM品系中，眼部色素丧失的程度与OKN反应性的相对降低之间存在密切关联。OKN反应的方向不对称性，通常在单眼从颞侧到鼻侧（T-N）而非从鼻侧到颞侧（N-T）刺激时出现，在DAM品系中随眼部无黑色素沉着的程度而改变。特别是，随着中央视网膜无黑色素沉着严重程度的增加，T-N OKN反应逐渐降低。在T-N反应性中度至重度降低的DAM品系中，N-T反应性相对降低较少。因此，中央视网膜似乎在介导对T-N刺激的反应中起主要作用，而周边视网膜介导两个方向的反应。视动性眼震也为该突变品系中发生的视网膜变性程度以及视网膜色素上皮和光感受器的逐渐丧失提供了一个有用的指标。
