To specifically infect postsynaptic Re neurons with mCherry or hM3Dq-mCherry, AAV-Cre was injected into the vLGN/IGL. For monosynaptic tracing the inputs to Re, RV virus was injected into Re. (From BrainVTA) Pub Date: 2020-11-10,  DOI: 10.1016/j.neuron.2020.10.023  Email: [email protected]
Xiaodan Huang, Pengcheng Huang, Lu Huang, Zhengfang Hu, Xianwei Liu, Jiawei Shen, Yue Xi, Yan Yang, Yunwei Fu, Qian Tao, Song Lin, Anding Xu, Fuqiang Xu, Tian Xue, Kwok-Fai So, Haohong Li and Chaoran Ren Light exerts profound effects on cognitive functions across species, including humans. However, the neuronal mechanisms underlying the effects of light on cognitive functions are poorly understood. In this study, we show that long-term exposure to bright-light treatment promotes spatial memory through a di-synaptic visual circuit related to the nucleus reuniens (Re). Specifically, a subset of SMI-32-expressing ON-type retinal ganglion cells (RGCs) innervate CaMKIIa neurons in the thalamic ventral lateral geniculate nucleus and intergeniculate leaflet (vLGN/IGL), which in turn activate CaMKIIa neurons in the Re. Specific activation of vLGN/IGL-projecting RGCs, activation of Re-projecting vLGN/IGL neurons, or activation of postsynaptic Re neurons is sufficient to promote spatial memory. Furthermore, we demonstrate that the spatial-memory-promoting effects of light treatment are dependent on the activation of vLGN/IGL-projecting RGCs, Re-projecting vLGN/IGL neurons, and Re neurons. Our results reveal a dedicated subcortical visual circuit that mediates the spatial-memory-promoting effects of light treatment.