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1. Grid cells, border cells, and discrete complex analysis

   https://doi.org/10.3389/fncom.2023.1242300  

   Dabaghian, Yuri (October 2023, Frontiers in Computational Neuroscience)

   Wu, Si (Ed.)

   We propose a mechanism enabling the appearance of border cells—neurons firing at the boundaries of the navigated enclosures. The approach is based on the recent discovery of discrete complex analysis on a triangular lattice, which allows constructing discrete epitomes of complex-analytic functions and making use of their inherent ability to attain maximal values at the boundaries of generic lattice domains. As it turns out, certain elements of the discrete-complex framework readily appear in the oscillatory models of grid cells. We demonstrate that these models can extend further, producing cells that increase their activity toward the frontiers of the navigated environments. We also construct a network model of neurons with border-bound firing that conforms with the oscillatory models. 

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2. Neuromorphic place cells

   https://doi.org/10.1088/2634-4386/ad48b0  

   Chen, Zhaoqi; Nasrallah, Alia; Etienne-Cummings, Ralph (May 2024, Neuromorphic Computing and Engineering)

   Abstract A neuromorphic simultaneous localization and mapping (SLAM) system shows potential for more efficient implementation than its traditional counterpart. At the mean time a neuromorphic model of spatial encoding neurons in silicon could provide insights on the functionality and dynamic between each group of cells. Especially when realistic factors including variations and imperfections on the neural movement encoding are presented to challenge the existing hypothetical models for localization. We demonstrate a mixed-mode implementation for spatial encoding neurons including theta cells, egocentric place cells, and the typical allocentric place cells. Together, they form a biologically plausible network that could reproduce the localization functionality of place cells observed in rodents. The system consists of a theta chip with 128 theta cell units and an FPGA implementing 4 networks for egocentric place cells formation that provides the capability for tracking on a 11 by 11 place cell grid. Experimental results validate the robustness of our model when suffering from as much as 18% deviation, induced by parameter variations in analog circuits, from the mathematical model of theta cells. We provide a model for implementing dynamic neuromorphic SLAM systems for dynamic-scale mapping of cluttered environments, even when subject to significant errors in sensory measurements and real-time analog computation. We also suggest a robust approach for the network topology of spatial cells that can mitigate neural non-uniformity and provides a hypothesis for the function of grid cells and the existence of egocentric place cells. 

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3. Two distinct trophectoderm lineage stem cells from human pluripotent stem cells

   https://doi.org/10.1016/j.jbc.2021.100386  

   Mischler, Adam; Karakis, Victoria; Mahinthakumar, Jessica; Carberry, Celeste K.; San Miguel, Adriana; Rager, Julia E.; Fry, Rebecca C.; Rao, Balaji M. (January 2021, Journal of Biological Chemistry)

   null (Ed.)
4. CD8 + T cells and NK cells: parallel and complementary soldiers of immunotherapy

   https://doi.org/10.1016/j.coche.2017.11.006  

   Rosenberg, Jillian; Huang, Jun (March 2018, Current Opinion in Chemical Engineering)
5. Steps toward the generation of ovarian somatic cells from pluripotent stem cells

   Bothun, Alisha; Woods, Dori C (December 2020, Clinical Theriogenology Journal)

   The generation of functional gametes, both eggs and sperm, from murine pluripotent stem cell (PSC) sources, has set the stage for the eventual use of this emerging technology in other species. With the field enthusiastically embracing this eventuality, in particular for animal conservation efforts, there are a number of key factors to consider regarding the applicability of these methods across species, particularly with regard to the generation of eggs. To date, published studies point to the need for fetal somatic tissue and primitive granulosa cells to serve as a niche for the growth and maturation of oocytes generated from PSCs. In practice, the need for such tissue represents a major limitation when attempting to apply this to species in which access to fetal ovaries is limited or unethical. To circumvent this, we and others have derived methods to generate ovarian granulosa cells from PSCs, albeit with low yield. Herein we present an update on the status of generating early stage granulosa cells from PSCs, and provide evidence for improvements based on a stepwise, 2-dimensional protocol for the directed differentiation of human PSCs. 

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