@article {69138, title = {Connectomic reconstruction predicts visual features used for navigation.}, journal = {Nature}, volume = {634}, year = {2024}, month = {2024 Oct 02}, pages = {181-190}, abstract = {

Many animals use visual information to navigate, but how such information is encoded and integrated by the navigation system remains incompletely understood. In Drosophila melanogaster, EPG neurons in the central complex compute the heading direction by integrating visual input from ER neurons, which are part of the anterior visual pathway (AVP). Here we densely reconstruct all neurons in the AVP using electron-microscopy data. The AVP comprises four neuropils, sequentially linked by three major classes of neurons: MeTu neurons, which connect the medulla in the optic lobe to the small unit of the anterior optic tubercle (AOTUsu) in the central brain; TuBu neurons, which connect the AOTUsu to the bulb neuropil; and ER neurons, which connect the bulb to the EPG neurons. On the basis of morphologies, connectivity between neural classes and the locations of synapses, we identify distinct information channels that originate from four types of MeTu neurons, and we further divide these into ten subtypes according to the presynaptic connections in the medulla and the postsynaptic connections in the AOTUsu. Using the connectivity of the entire AVP and the dendritic fields of the MeTu neurons in the optic lobes, we infer potential visual features and the visual area from which any ER neuron receives input. We confirm some of these predictions physiologically. These results provide a strong foundation for understanding how distinct sensory features can be extracted and transformed across multiple processing stages to construct higher-order cognitive representations.

}, doi = {10.1038/s41586-024-07967-z}, url = {https://doi.org/10.1038/s41586-024-07967-z}, author = {Garner, Dustin and Kind, Emil and Yuet Ha Lai, Jennifer and Nern, Aljoscha and Zhao, Arthur and Houghton, Lucy and Sancer, Gizem and Wolff, Tanya and Rubin, Gerald M and Wernet, Mathias F and Kim, Sung Soo} } @article {65234, title = {Generation of stable heading representations in diverse visual scenes.}, journal = {Nature}, volume = {576}, year = {2019}, month = {2019 Nov 20}, pages = {126-31}, abstract = {

Many animals rely on an internal heading representation when navigating in varied environments. How this representation is linked to the sensory cues that define different surroundings is unclear. In the fly brain, heading is represented by {\textquoteright}compass{\textquoteright} neurons that innervate a ring-shaped structure known as the ellipsoid body. Each compass neuron receives inputs from {\textquoteright}ring{\textquoteright} neurons that are selective for particular visual features; this combination provides an ideal substrate for the extraction of directional information from a visual scene. Here we combine two-photon calcium imaging and optogenetics in tethered flying flies with circuit modelling, and show how the correlated activity of compass and visual neurons drives plasticity, which flexibly transforms two-dimensional visual cues into a stable heading representation. We also describe how this plasticity enables the fly to convert a partial heading representation, established from orienting within part of a novel setting, into a complete heading representation. Our results provide mechanistic insight into the memory-related computations that are essential for flexible navigation in varied surroundings.

}, issn = {1476-4687}, doi = {10.1038/s41586-019-1767-1}, author = {Kim, Sung Soo and Hermundstad, Ann M and Romani, Sandro and Abbott, L F and Jayaraman, Vivek} } @article {6719, title = {Independent optical excitation of distinct neural populations.}, journal = {Nature Methods}, volume = {11}, year = {2014}, month = {2014 Feb 9}, pages = {338-46}, abstract = {

Optogenetic tools enable examination of how specific cell types contribute to brain circuit functions. A long-standing question is whether it is possible to independently activate two distinct neural populations in mammalian brain tissue. Such a capability would enable the study of how different synapses or pathways interact to encode information in the brain. Here we describe two channelrhodopsins, Chronos and Chrimson, discovered through sequencing and physiological characterization of opsins from over 100 species of alga. Chrimson{\textquoteright}s excitation spectrum is red shifted by 45 nm relative to previous channelrhodopsins and can enable experiments in which red light is preferred. We show minimal visual system-mediated behavioral interference when using Chrimson in neurobehavioral studies in Drosophila melanogaster. Chronos has faster kinetics than previous channelrhodopsins yet is effectively more light sensitive. Together these two reagents enable two-color activation of neural spiking and downstream synaptic transmission in independent neural populations without detectable cross-talk in mouse brain slice.

}, issn = {1548-7105}, doi = {10.1038/nmeth.2836}, author = {Klapoetke, Nathan C and Murata, Yasunobu and Kim, Sung Soo and Pulver, Stefan R and Birdsey-Benson, Amanda and Cho, Yong Ku and Morimoto, Tania K and Chuong, Amy S and Carpenter, Eric J and Tian, Zhijian and Wang, Jun and Xie, Yinlong and Yan, Zhixiang and Zhang, Yong and Chow, Brian Y and Surek, Barbara and Melkonian, Michael and Jayaraman, Vivek and Constantine-Paton, Martha and Wong, Gane Ka-Shu and Boyden, Edward S} }