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1. Effects of social context manipulation on dorsal and ventral hippocampal neuronal responses

   https://doi.org/10.1002/hipo.23507  

   Wu, Wen‐Yi ; Yiu, Eunice ; Ophir, Alexander G. ; Smith, David M. ( February 2023 , Hippocampus)

   The hippocampus is critical for contextual memory and has recently been implicated in various kinds of social memory. Traditionally, studies of hippocampal context coding have manipulated elements of the background environment, such as the shape and color of the apparatus. These manipulations produce large shifts in the spatial firing patterns, a phenomenon known as remapping. These findings suggest that the hippocampus encodes and differentiates contexts by generating unique spatial firing patterns for each environment a subject encounters. However, we do not know whether the hippocampus encodes social contexts defined by the presence of particular conspecifics. We examined this by exposing rats to a series of manipulations of the social context, including the presence of familiar male, unfamiliar male and female conspecifics, in order to determine whether remapping is a plausible mechanism for encoding socially‐defined contexts. Because the dorsal and ventral regions of the hippocampus are thought to play different roles in spatial and social cognition, we recorded neurons in both regions. Surprisingly, we found little evidence of remapping in response to manipulation of the social context in either the dorsal or ventral hippocampus, although we saw typical remapping in response to changing the background color. This result suggests that remapping is not the primary mechanism for encoding different social contexts. However, we found that a subset of hippocampal neurons fired selectively near the cages that contained the conspecifics, and these responses were most prevalent in the ventral hippocampus. We also found a striking increase in the spatial information content of ventral hippocampal firing patterns. These results indicate that the ventral hippocampus is sensitive to changes in the social context and neurons that respond selectively near the conspecific cages could play an important, if not fully understood role in encoding the conjunction of conspecifics, their location and the environment.

    

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2. A Hierarchical View of Gecko Locomotion: Photic Environment, Physiological Optics, and Locomotor Performance

   https://doi.org/10.1093/icb/icz092  

   Higham, Timothy E. ; Schmitz, Lars ( June 2019 , Integrative and Comparative Biology)

   Terrestrial animals move in complex habitats that vary over space and time. The characteristics of these habitats are not only defined by the physical environment, but also by the photic environment, even though the latter has largely been overlooked. For example, numerous studies of have examined the role of habitat structure, such as incline, perch diameter, and compliance, on running performance. However, running performance likely depends heavily on light level. Geckos are an exceptional group for analyzing the role of the photic environment on locomotion as they exhibit several independent shifts to diurnality from a nocturnal ancestor, they are visually-guided predators, and they are extremely diverse. Our initial goal is to discuss the range of photic environments that can be encountered in terrestrial habitats, such as day versus night, canopy cover in a forest, fog, and clouds. We then review the physiological optics of gecko vision with some new information about retina structures, the role of vision in motor-driven behaviors, and what is known about gecko locomotion under different light conditions, before demonstrating the effect of light levels on gecko locomotor performance. Overall, we highlight the importance of integrating sensory and motor information and establish a conceptual framework as guide for future research. Several future directions, such as understanding the role of pupil dynamics, are dependent on an integrative framework. This general framework can be extended to any motor system that relies on sensory information, and can be used to explore the impact of performance features on diversification and evolution.

    

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3. A CONTRASTIVE LEARNING-BASED APPROACH TO MEASURE SPATIAL COUPLING AMONG BRAIN NETWORKS: A SCHIZOPHRENIA STUDY

   https://doi.org/10.1109/ISBI52829.2022.9761466  

   Hassanzadeh, Reihaneh ; Calhoun, Vince ( January 2022 , IEEE International Symposium on Biomedical Imaging (ISBI))

   Resting-state functional magnetic resonance imaging (rsfMRI) has become a widely used approach for detecting subtle differences in functional brain fluctuations in various studies of the healthy and disordered brain. Such studies are often based on temporal functional connectivity (i.e., the correlation between time courses derived from regions or networks within the fMRI data). While being successful for a number of tasks, temporal connectivity does not fully leverage the available spatial information. In this research study, we present a new perspective on spatial functional connectivity, which involves learning patterns of spatial coupling among brain networks by utilizing recent advances in deep learning as well as the contrastive learning framework. We show that we can learn domain-specific mappings of brain networks that can, in turn, be used to characterize differences between schizophrenia patients and control. Furthermore, we show that the coupling of intradomain networks in the controls is stronger than in patients suffering from the disorder. We also evaluate the coupling among networks of different domains and find various patterns of stronger or weaker coupling among certain domains, which provide additional insights about the brain. 

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4. Evolutionary and cardio‐respiratory physiology of air‐breathing and amphibious fishes

   https://doi.org/10.1111/apha.13406  

   Damsgaard, Christian ; Baliga, Vikram B. ; Bates, Eric ; Burggren, Warren ; McKenzie, David J. ; Taylor, Edwin ; Wright, Patricia A. ( November 2019 , Acta Physiologica)

   Air‐breathing and amphibious fishes are essential study organisms to shed insight into the required physiological shifts that supported the full transition from aquatic water‐breathing fishes to terrestrial air‐breathing tetrapods. While the origin of air‐breathing in the evolutionary history of the tetrapods has received considerable focus, much less is known about the evolutionary physiology of air‐breathing among fishes. This review summarizes recent advances within the field with specific emphasis on the cardiorespiratory regulation associated with air‐breathing and terrestrial excursions, and how respiratory physiology of these living transitional forms are affected by development and personality. Finally, we provide a detailed and re‐evaluated model of the evolution of air‐breathing among fishes that serves as a framework for addressing new questions on the cardiorespiratory changes associated with it. This review highlights the importance of combining detailed studies on piscine air‐breathing model species with comparative multi‐species studies, to add an additional dimension to our understanding of the evolutionary physiology of air‐breathing in vertebrates.

    

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5. A multivariate approach reveals diversity of ontogenetic niche shifts across taxonomic and functional groups

   https://doi.org/10.1111/fwb.13463  

   Rudolf, Volker H. W. ( December 2019 , Freshwater Biology)

   Shifts in the fundamental and realised niche of individuals during their ontogeny are ubiquitous in nature, but we know little about what aspects of the niche change and how these changes vary across species within communities. However, this knowledge is essential to predict the dynamics of populations and communities and how they respond to environmental change.

   Here I introduce a range of metrics to describe different aspects of shifts in the realised trophic niche of individuals based on stable isotopes. Applying this multi‐variate approach to 2,272 individuals from 13 taxonomic and functional distinct species (Amphibia, Hemiptera, Coleoptera, Odonata) sampled in natural pond communities allowed me to: (1) describe and quantify the diversity of trophic niche shift patterns over ontogeny in multi‐dimensional space, and (2) identify what aspects of ontogenetic shifts vary across taxa, and functional groups.

   Results revealed that species can differ substantially in which aspects of the trophic niche change and how they change over ontogeny. Interestingly, patterns of ontogenetic niche shifts grouped in distinct taxonomic clusters in multi‐variate space, including two distinct groups of predators (Hemiptera versus Odonata). Given the differences in traits (especially feeding mode) across groups, this suggests that differences in ontogenetic niche shifts across species could at least partially be explained by variation in traits and functional roles of species.

   These results emphasise the importance of a multivariate approach to capture the large diversity of trophic niche shifts patterns possible in natural communities and suggest that differences in ontogenetic niche shifts follow general patterns.

    

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