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Visual System

開催日 2014/9/11
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Response selectivity of thalamocortical axons in mouse primary visual cortex

  • P1-171
  • 根東 覚 / Satoru Kondo:1 大木 研一 / Kenichi Ohki:1,2 
  • 1:九州大学大学院 / Department of Molecular Physiology, Graduate School of Medical Sciences, Kyushu University 2:CREST, JST / CREST, JST 

The prominent aspect of primary visual cortex (V1) is the response selectivity to visual stimulus features. Layer 4, the major entrance layer of V1, receives visual input from lateral geniculate nucleus (LGN) of thalamus. Layer 4 excitatory neurons in mouse V1 possess high selectivity for stimulus orientation. Recent studies indicated that thalamocortical axons targeting layer 1, another recipient layer of thalamic input, had sharp orientation selectivity (Cruz-Martin et al., 2014). However, it is still unknown whether thalamocortical axons arborizing in layer 4 also carry sharp orientation tuning. To answer this question, we performed in vivo two-photon calcium imaging of thalamocortical axons in mouse V1 and investigated their response selectivity to visual stimuli. For axonal calcium imaging, GCaMP6s, genetically encoded calcium indicator, was locally expressed in LGN neurons by AAV-mediated method. Boutons of thalamocortical axon expressing GCaMP6s were clearly visible in layers 1 and 4 of primary visual cortex and we could record their response selectivity to visual stimuli. We found thalamocortical axons arborizing in layer 4 had broad orientation selectivity, while axons in layer 1 had mixture of sharp and broad orientation tuning. These results suggest that layer 4 neurons receive largely untuned input from LGN, although they have sharp orientation selectivity.

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