Normal behavioral responses to light and darkness and the pupillary light reflex are dependent upon the olivary pretectal nucleus in the diurnal Nile grass rat.
Normal behavioral responses to light and darkness and the pupillary light reflex are dependent upon the olivary pretectal nucleus in the diurnal Nile grass rat.
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DOI：
10.1016/j.neuroscience.2017.05.002
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发表时间：
2017-07-04
期刊：
影响因子：
3.3
通讯作者：
Nunez AA
中科院分区：
文献类型：
--
作者：
Gall AJ;Khacherian OS;Ledbetter B;Deats SP;Luck M;Smale L;Yan L;Nunez AA
橄榄顶盖前核(OPT)是一种中脑结构，接受双向视网膜投射，参与瞳孔光反射，并与膝间小叶(IGL)相互连接，IGL是尼罗河大鼠白天对光脉冲的行为反应(即掩蔽)的视网膜重要脑区。在这里，我们研究了OPT，并评估了草鼠对不同光照条件的行为反应，以及它们对光暴露的焦虑样反应。在12h：12h的光暗(LD)条件下，对照组大鼠保持白天活动，而OPT损伤的大鼠表现出更多的夜间活动模式。然而，当置于持续的黑暗中时，OPT损毁的草鼠在它们主观的一天中变得更加活跃，这表明对光的夸大掩蔽反应可能是OPT损毁对LD运动活动的影响的原因。为了验证这一假说，我们向对照组和有OPT损伤的草鼠提供暗脉冲和光脉冲；对照组对光的反应增加了它们的活动，而那些有OPT损伤的鼠对黑暗的反应显著增加了活动。此外，当被放置在7小时的超传统LD周期中时，OPT损伤的动物在黑暗中比对照组更活跃。OPT损伤也消除了瞳孔的光反射，但不影响焦虑样行为。最后，在有OPT损害的动物中，光不像对照组那样诱导膝状体腹外侧核Fos的表达。总之，这些结果表明，草鼠对光明和黑暗的掩蔽反应依赖于皮质下视觉外壳内的核团。
The olivary pretectal nucleus (OPT) is a midbrain structure that receives reciprocal bilateral retinal projections, is involved in the pupillary light reflex, and connects reciprocally with the intergeniculate leaflet (IGL), a retinorecipient brain region that mediates behavioral responses to light pulses (i.e., masking) in diurnal Nile grass rats. Here, we lesioned the OPT and evaluated behavioral responses in grass rats to various lighting conditions, as well as their anxiety-like responses to light exposure. While control grass rats remained diurnal, grass rats with OPT lesions exhibited a more night-active pattern under 12h:12h light-dark (LD) conditions. However, when placed in constant darkness, OPT lesioned grass rats became more active during their subjective day, suggesting that an exaggerated masking response to light may be responsible for the effect of OPT lesions on locomotor activity in LD. To test this hypothesis, we presented dark and light pulses to controls and grass rats with OPT lesions; controls increased their activity in response to light, whereas those with OPT lesions significantly increased activity in response to darkness. Further, when placed in a 7-hr ultradian LD cycle, animals with OPT lesions were more active during darkness than controls. OPT lesions also abolished the pupillary light reflex, but did not affect anxiety-like behaviors. Finally, in animals with OPT lesions, light did not induce Fos expression in the ventrolateral geniculate nucleus, as it did in controls. Altogether, these results suggest that masking responses to light and darkness are dependent upon nuclei within the subcortical visual shell in grass rats.
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