Hodos W, Miller R F, Ghim M M, Fitzgerald M E, Toledo C, Reiner A
Department of Psychology, University of Maryland at College Park, USA.
Vis Neurosci. 1998 Mar-Apr;15(2):273-87. doi: 10.1017/s0952523898152070.
Choroidal blood flow (ChBF) in birds is regulated by a neural circuit whose components are the retina, the suprachiasmatic nucleus, the medial division of the Edinger-Westphal nucleus (EWM), the ciliary ganglion, and the choriod. We have previously shown that lesions of EWM appear to result in pathological alterations in the retina. To determine whether EWM lesions also lead to altered visual functions, we have examined the effects of EWM lesions on visual acuity in pigeons. Bilateral lesions of EWM were made electrolytically, and visual acuity for high-contrast, square-wave gratings was determined behaviorally about 1 year later and compared to that of a group of pigeons that had received sham lesions of EW about 1 year prior to acuity testing. Because lesions targeting EWM invariably resulted in damage to the adjoining lateral part of the Edinger-Westphal nucleus (EWL), which controls pupillary constriction and accommodation, two additional control groups were studied. In one such control group, bilateral lesions in the area pretectalis (AP), which innervates the pupillary control part of EWL and thereby controls pupillary constriction, were made and the effects on visual acuity determined about 1 year later. In the second such control group, the effects of acute accommodative and pupillary dysfunction on acuity were studied in pigeons made cycloplegic. The accuracy of all lesions was later confirmed histologically. The mean acuities of birds with AP lesions (9.1+/-1.4 cycles/deg) and sham lesions (7.1+/-1.5 cycles/deg) were not significantly different from normal, based on published normative data on pigeons. In contrast, pigeons with lesions that completely destroyed EW bilaterally showed visual acuity (2.7+/-0.1 cycles/deg) that was well below the acuity of the sham and AP-lesion control groups. The acuity of the cycloplegic pigeons (4.8+/-0.3 cycles/deg) and one pigeon with a nearly complete bilateral EWL but a unilateral EWM lesion (6.4 cycles/deg) indicated that only about half of the loss with a bilateral EW lesion could be attributed to accommodative dysfunction. Thus, bilateral destruction of EWM appears to have led to a loss in visual acuity. This conclusion suggests that disruption of adaptive neural regulation of ChBF may impair visual function. Destruction of EWM was, however, associated with damage to the somatic components of the oculomotor and trochlear nuclei. The possibility cannot be excluded that such damage also contributed to the acuity loss.
鸟类的脉络膜血流量（ChBF）由一个神经回路调节，该神经回路的组成部分包括视网膜、视交叉上核、动眼神经副核内侧部（EWM）、睫状神经节和脉络膜。我们之前已经表明，EWM损伤似乎会导致视网膜发生病理改变。为了确定EWM损伤是否也会导致视觉功能改变，我们研究了EWM损伤对鸽子视力的影响。通过电解法进行EWM双侧损伤，约1年后通过行为学方法测定高对比度方波光栅的视力，并与一组在视力测试前约1年接受EW假损伤的鸽子进行比较。由于针对EWM的损伤总是会导致相邻的动眼神经副核外侧部（EWL）受损，而EWL控制瞳孔收缩和调节，因此研究了另外两个对照组。在其中一个对照组中，对顶盖前区（AP）进行双侧损伤，AP支配EWL的瞳孔控制部分从而控制瞳孔收缩，约1年后测定对视力的影响。在第二个对照组中，研究了在使用睫状肌麻痹剂的鸽子中急性调节和瞳孔功能障碍对视力的影响。所有损伤的准确性随后通过组织学方法得到证实。根据已发表的鸽子标准数据，AP损伤组（9.1±1.4周/度）和假损伤组（7.1±1.5周/度）鸟类的平均视力与正常情况无显著差异。相比之下，双侧EW完全损毁的鸽子视力（2.7±0.1周/度）远低于假损伤组和AP损伤对照组。使用睫状肌麻痹剂的鸽子（4.8±0.3周/度）以及一只双侧EWL几乎完全损毁但单侧EWM损伤鸽子的视力（6.4周/度）表明，双侧EW损伤导致的视力损失中只有约一半可归因于调节功能障碍。因此，双侧EWM损毁似乎导致了视力下降。这一结论表明，ChBF适应性神经调节的破坏可能会损害视觉功能。然而，EWM的损毁与动眼神经核和滑车神经核的躯体成分受损有关。不能排除这种损伤也导致视力下降的可能性。
