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Visual System

開催日 2014/9/13
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Roles of the extrageniculate pathway in properties of higher visual cortices of mice

  • P3-116
  • 任海 学 / Manavu Tohmi:1 目黒 玲子 / Reiko Meguro:2 塚野 浩明 / Hiroaki Tsukano:1 菱田 竜一 / Ryuichi Hishida:1 車田 正男 / Masao Norita:2 澁木 克栄 / Katsuei Shibuki:1 
  • 1:新潟大学脳研究所 / Brain Res.Inst., Niigata Univ. 2:新潟大学 大学院・医歯学総合研究科 / Dept Neurobiol Anat, Sch Med, Niigata Univ, Niigata, Japan 

Visual information is conveyed through the extrageniculate visual pathway, which runs from the retina via the superior colliculus (SC) and the lateral posterior nucleus (LPN) of the thalamus to the higher visual cortex. Although this pathway plays a critical role in the visual capabilities of many mammalian species, its functional role in the higher visual cortex remains unclear. Here, we investigated visual cortical areas in anesthetized mice to evaluate the role of the extrageniculate visual pathway for determining their specialized properties. We identified higher visual areas of mice, such as LM, AL, AM, and RL areas, and examined their tuning profiles for stimulus speed using flavoprotein fluorescence imaging. The preferred stimulus speeds of neurons in the higher visual areas were higher than those of the primary visual cortex (V1), and the speed-tuning properties of the higher visual areas were different from each other. V1-ablated mice exhibited response patterns that were similar to those observed in normal mice, and the differences in the visual properties were preserved. After SC destruction, these preferences for high-speeds disappeared, and their tuning profiles became similar to that of the V1, whereas the tuning profile of the V1 was relatively normal. To determine the routes via which the SC sends visual information to the higher visual areas, tracers labeled with red or green fluorescence, were injected into 2 visual areas. It was revealed that each of visual cortical area has reciprocal connections with specific subregions of the LPN, and that these regions were distinct from each other with small overlaps. Double injection into two regions corresponding to different retinotopic field in the same visual cortical area revealed that these subregions of the LPN have retinotopic architecture. These results suggest that visual properties of higher visual areas in mice depend on inputs from the SC via specific thalamic nuclei, rather than those from the V1.

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