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1. Drosophila larvae form appetitive and aversive associative memory in response to thermal conditioning

   https://doi.org/10.1371/journal.pone.0303955  

   Polizos, Nikolaos T; Dancausse, Stephanie; Rios, Consuelo; Klein, Mason (September 2024, PLOS ONE)

   Skoulakis, Efthimios_M C (Ed.)

   Organisms have evolved the ability to detect, process, and respond to many different surrounding stimuli in order to successfully navigate their environments. Sensory experiences can also be stored and referenced in the form of memory. TheDrosophilalarva is a simple model organism that can store associative memories during classical conditioning, and is well-suited for studying learning and memory at a fundamental level. Much progress has been made in understanding larval learning behavior and the associated neural circuitry for olfactory conditioning, but other sensory systems are relatively unexplored. Here, we investigate memory formation in larvae treated with a temperature-based associative conditioning protocol, pairing normally neutral temperatures with appetitive (fructose, FRU) or aversive (salt, NaCl) stimuli. We test associative memory using thermal gradient geometries, and quantify navigation strength towards or away from conditioned temperatures. We find that larvae demonstrate short-term associative learning. They navigate towards warmer or cooler temperatures paired with FRU, and away from warmer or cooler temperatures paired with NaCl. These results, especially when combined with future investigations of thermal memory circuitry in larvae, should provide broader insight into how sensory stimuli are encoded and retrieved in insects and more complex systems. 

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2. Bioinspired Model for Drosophila Larva Crawling Locomotion

   https://doi.org/10.1109/DCAS65331.2025.11045489  

   Perera, Dulanjana M; Byrd, Nathan; Huang, Yuhan; Le, Xuan Tung; Arachchige, Dimuthu_D K; Wang, Zhaosen; Zarin, Aref A; Godage, Isuru S (April 2025, IEEE)

   Fruit flies or Drosophila larvae exhibit a diverse range of locomotion gaits enabled by their soft, segmented bodies and intricate muscle arrangements. Their bodies, composed of multiple segments, are synchronously activated to propel forward through a combination of muscle elongation and contraction. Soft robotic systems, inspired by such biological marvels, face significant challenges in replicating these complex behaviors due to the intricate interplay between muscle activation, soft body dynamics, and frictional forces. To address these challenges, we propose a reduced-order model that captures the essential features of larval crawling. By modeling segments as a combination of prismatic and revolute joints, we can simulate the nonlinear motion resulting from muscle activation and body deformation. Our model demonstrates the potential of this approach to accurately describe larval movement, as validated by comparisons with actual larval trajectories. This research offers valuable insights into the design and control of soft robots and provides a framework for biologists to investigate the complex mechanisms of neuromuscular coordination in larvae. 

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3. Efficient and accurate extraction of in vivo calcium signals from microendoscopic video data

   https://doi.org/10.7554/eLife.28728  

   Zhou, Pengcheng; Resendez, Shanna L; Rodriguez-Romaguera, Jose; Jimenez, Jessica C; Neufeld, Shay Q; Giovannucci, Andrea; Friedrich, Johannes; Pnevmatikakis, Eftychios A; Stuber, Garret D; Hen, Rene; et al (February 2018, eLife)

   In vivo calcium imaging through microendoscopic lenses enables imaging of previously inaccessible neuronal populations deep within the brains of freely moving animals. However, it is computationally challenging to extract single-neuronal activity from microendoscopic data, because of the very large background fluctuations and high spatial overlaps intrinsic to this recording modality. Here, we describe a new constrained matrix factorization approach to accurately separate the background and then demix and denoise the neuronal signals of interest. We compared the proposed method against previous independent components analysis and constrained nonnegative matrix factorization approaches. On both simulated and experimental data recorded from mice, our method substantially improved the quality of extracted cellular signals and detected more well-isolated neural signals, especially in noisy data regimes. These advances can in turn significantly enhance the statistical power of downstream analyses, and ultimately improve scientific conclusions derived from microendoscopic data. 

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4. Correcting motion induced fluorescence artifacts in two-channel neural imaging

   https://doi.org/10.1371/journal.pcbi.1010421  

   Creamer, Matthew S.; Chen, Kevin S.; Leifer, Andrew M.; Pillow, Jonathan W. (September 2022, PLOS Computational Biology)

   Louis, Matthieu (Ed.)

   Imaging neural activity in a behaving animal presents unique challenges in part because motion from an animal’s movement creates artifacts in fluorescence intensity time-series that are difficult to distinguish from neural signals of interest. One approach to mitigating these artifacts is to image two channels simultaneously: one that captures an activity-dependent fluorophore, such as GCaMP, and another that captures an activity-independent fluorophore such as RFP. Because the activity-independent channel contains the same motion artifacts as the activity-dependent channel, but no neural signals, the two together can be used to identify and remove the artifacts. However, existing approaches for this correction, such as taking the ratio of the two channels, do not account for channel-independent noise in the measured fluorescence. Here, we present Two-channel Motion Artifact Correction (TMAC), a method which seeks to remove artifacts by specifying a generative model of the two channel fluorescence that incorporates motion artifact, neural activity, and noise. We use Bayesian inference to infer latent neural activity under this model, thus reducing the motion artifact present in the measured fluorescence traces. We further present a novel method for evaluating ground-truth performance of motion correction algorithms by comparing the decodability of behavior from two types of neural recordings; a recording that had both an activity-dependent fluorophore and an activity-independent fluorophore (GCaMP and RFP) and a recording where both fluorophores were activity-independent (GFP and RFP). A successful motion correction method should decode behavior from the first type of recording, but not the second. We use this metric to systematically compare five models for removing motion artifacts from fluorescent time traces. We decode locomotion from a GCaMP expressing animal 20x more accurately on average than from control when using TMAC inferred activity and outperforms all other methods of motion correction tested, the best of which were ~8x more accurate than control. 

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5. Transplantation and Noninvasive Longitudinal In Vivo Imaging of Parathyroid Cells: A Proof-of-Concept Study

   https://doi.org/10.1177/09636897241241995  

   Bränström, Robert; van_Krieken, Pim P; Fröbom, Robin; Juhlin, C Christofer; Shabo, Ivan; Leibiger, Barbara; Leibiger, Ingo B; Berggren, Per-Olof; Aspinwall, Craig A (January 2024, Cell Transplantation)

   The parathyroid cell is a vital regulator of extracellular calcium levels, operating through the secretion of parathyroid hormone (PTH). Despite its importance, the regulation of PTH secretion remains complex and not fully understood, representing a unique interplay between extracellular and intracellular calcium, and hormone secretion. One significant challenge in parathyroid research has been the difficulty in maintaining cells ex vivo for in-depth cellular investigations. To address this issue, we introduce a novel platform for parathyroid cell transplantation and noninvasive in vivo imaging using the anterior chamber of the eye as a transplantation site. We found that parathyroid adenoma tissue transplanted into the mouse eye engrafted onto the iris, became vascularized, and retained cellular composition. Transplanted animals exhibited elevated PTH levels, indicating a functional graft. With in vivo confocal microscopy, we were able to repetitively monitor parathyroid graft morphology and vascularization. In summary, there is a pressing need for new methods to study complex cellular processes in parathyroid cells. Our study provides a novel approach for noninvasive in vivo investigations that can be applied to understand parathyroid physiology and pathology under physiological and pathological conditions. This innovative strategy can deepen our knowledge on parathyroid function and disease. 

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