Masterson Sean P, Govindaiah Govin, Guido William, Bickford Martha E
bioRxiv. 2024 Jul 16:2024.07.12.603141. doi: 10.1101/2024.07.12.603141.
Projections from each eye are segregated in separate domains within the dorsal lateral geniculate nucleus (dLGN). Yet, studies indicate that the activity of single dLGN neurons can be influenced by visual stimuli presented to either eye. In this study we explored whether intrinsic circuits mediate binocular interactions in the mouse dLGN. We employed dual color optogenetics to selectively activate input from each eye and recorded synaptic responses in thalamocortical (relay) cells as well as inhibitory interneurons, which have extensive dendritic arbors that are not confined to eye specific domains. While most relay cells received monocular retinal input, most interneurons received binocular retinal input; consequently, the majority of dLGN relay cells received binocular retinogeniculate-evoked inhibition. Moreover, in recordings from adjacent pairs of relay cells and interneurons, the most common relationship observed was binocular excitation of interneurons paired with binocular inhibition of adjacent relay cells. Finally, we found that dLGN interneurons are interconnected, displaying both monocular and binocular inhibition in response to retinal activation. In sum, our results indicate that geniculate interneurons provide one of the first locations where signals from the two eyes can be compared, integrated, and adjusted before being transmitted to cortex, shedding new light on the role of the thalamus in binocular vision.
In vitro dual color optogenetics examined convergence of eye-specific retinal inputs to thalamocortical (relay) cells and interneurons in the dLGNThe majority of relay cells receive monocular excitatory retinogeniculate input while the majority of interneurons receive binocular inputBinocular relay cells are located in and around the ipsilateral patch whereas binocular interneurons are distributed throughout the dLGNThe majority of relay cells receive binocular retinogeniculate-evoked inhibitiondLGN interneurons are interconnected, receiving both monocular and binocular retinogeniculate-evoked inhibition.
每只眼睛的投射在背外侧膝状核（dLGN）内的不同区域中是分开的。然而，研究表明，单个dLGN神经元的活动可受到呈现给任一只眼睛的视觉刺激的影响。在本研究中，我们探究了内在回路是否介导小鼠dLGN中的双眼相互作用。我们采用双色光遗传学来选择性激活来自每只眼睛的输入，并记录丘脑皮质（中继）细胞以及抑制性中间神经元中的突触反应，这些中间神经元具有广泛的树突分支，并不局限于眼睛特异性区域。虽然大多数中继细胞接受单眼视网膜输入，但大多数中间神经元接受双眼视网膜输入；因此，大多数dLGN中继细胞接受双眼视网膜膝状体诱发的抑制。此外，在相邻的中继细胞和中间神经元对的记录中，观察到的最常见关系是中间神经元的双眼兴奋与相邻中继细胞的双眼抑制配对。最后，我们发现dLGN中间神经元相互连接，在视网膜激活时表现出单眼和双眼抑制。总之，我们的结果表明，膝状体中间神经元提供了最早可对来自两只眼睛的信号进行比较、整合和调整的位置之一，然后再将其传输到皮层，这为丘脑在双眼视觉中的作用提供了新的见解。
体外双色光遗传学研究了眼睛特异性视网膜输入到dLGN中的丘脑皮质（中继）细胞和中间神经元的汇聚情况大多数中继细胞接受单眼兴奋性视网膜膝状体输入，而大多数中间神经元接受双眼输入双眼中继细胞位于同侧斑块及其周围，而双眼中间神经元分布在整个dLGN中大多数中继细胞接受双眼视网膜膝状体诱发的抑制dLGN中间神经元相互连接，接受单眼和双眼视网膜膝状体诱发的抑制
