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This paper examines the representations of the white woman in cross-cultural marriage in Ahdaf Soueif's The Map of Love in a contemporary deconstructive theory. The paper applies Judith Butler's revolutionary theory of gender and identity constructivism and performativity to clarify how the protagonist fights the gender norms and performances by having masculinity codes as a revolting means for emancipation. The paper tends to explore how colonial hegemony can create a cultural distance which is forced against the white woman by this marriage. It investigates the sociopolitical spatial divisions through the eye of the white woman who struggles because she chooses an ethnic husband. The paper applies a feminist theoretical framework to describe the prejudice and bias that appear after this marriage. "The manly woman" is the white woman who wears masculine features to subvert and oppose the gender bias which applies to her femininity. [ABSTRACT FROM AUTHOR]

Here, we review the basis of contextual memory at a conceptual and cellular level. We begin with an overview of the philosophical foundations of traversing space, followed by theories covering the material bases of contextual representations in the hippocampus (engrams), exploring functional characteristics of the cells and subfields within. Next, we explore various methodological approaches for investigating contextual memory engrams, emphasizing plasticity mechanisms. This leads us to discuss the role of neuromodulatory inputs in governing these dynamic changes. We then outline a recent hypothesis involving noradrenergic and dopaminergic projections from the locus coeruleus (LC) to different subregions of the hippocampus, in sculpting contextual representations, giving a brief description of the neuroanatomical and physiological properties of the LC. Finally, we examine how activity in the LC influences contextual memory processes through synaptic plasticity mechanisms to alter hippocampal engrams. Overall, we find that phasic activation of the LC plays an important role in promoting new learning and altering mnemonic processes at the behavioral and cellular level through the neuromodulatory influence of NE/DA in the hippocampus. These findings may provide insight into mechanisms of hippocampal remapping and memory updating, memory processes that are potentially dysregulated in certain psychiatric and neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Introduction: Spatial representations in the entorhinal cortex (EC) and hippocampus (HPC) are fundamental to cognitive functions like navigation and memory. These representations, embodied in spatial field maps, dynamically remap in response to environmental changes. However, current methods, such as Pearson's correlation coefficient, struggle to capture the complexity of these remapping events, especially when fields do not overlap, or transformations are non-linear. This limitation hinders our understanding and quantification of remapping, a key aspect of spatial memory function. Methods: We propose a family of metrics based on the Earth Mover's Distance (EMD) as a versatile framework for characterizing remapping. Results: The EMD provides a granular, noise-resistant, and rate-robust description of remapping. This approach enables the identification of specific cell types and the characterization of remapping in various scenarios, including disease models. Furthermore, the EMD's properties can be manipulated to identify spatially tuned cell types and to explore remapping as it relates to alternate information forms such as spatiotemporal coding. Discussion: We present a feasible, lightweight approach that complements traditional methods. Our findings underscore the potential of the EMD as a powerful tool for enhancing our understanding of remapping in the brain and its implications for spatial navigation, memory studies and beyond. [ABSTRACT FROM AUTHOR]

A behavioral strategy crucial to survival is directed navigation to a goal, such as a food or home location. One potential neural substrate for supporting goal-directed navigation is the parahippocampus, which contains neurons that represent an animal’s position, orientation, and movement through the world, and that change their firing activity to encode behaviorally relevant variables such as reward. However, little prior work on the parahippocampus has considered how neurons encode variables during goal-directed navigation in environments that dynamically change. Here, we recorded single units from rat parahippocampal cortex while subjects performed a goal-directed task. The maze dynamically changed goal-locations via a visual cue on a trial-to-trial basis, requiring subjects to use cue-location associations to receive reward. We observed a mismatch-like signal, with elevated neural activity on incorrect trials, leading to rate-remapping. The strength of this remapping correlated with task performance. Recordings during open-field foraging allowed us to functionally define navigational coding for a subset of the neurons recorded in the maze. This approach revealed that head-direction coding units remapped more than other functional-defined units. Taken together, this work thus raises the possibility that during goal-directed navigation, parahippocampal neurons encode error information reflective of an animal’s behavioral performance.

IntroductionSpatial representations in the entorhinal cortex (EC) and hippocampus (HPC) are fundamental to cognitive functions like navigation and memory. These representations, embodied in spatial field maps, dynamically remap in response to environmental changes. However, current methods, such as Pearson's correlation coefficient, struggle to capture the complexity of these remapping events, especially when fields do not overlap, or transformations are non-linear. This limitation hinders our understanding and quantification of remapping, a key aspect of spatial memory function.MethodsWe propose a family of metrics based on the Earth Mover's Distance (EMD) as a versatile framework for characterizing remapping.ResultsThe EMD provides a granular, noise-resistant, and rate-robust description of remapping. This approach enables the identification of specific cell types and the characterization of remapping in various scenarios, including disease models. Furthermore, the EMD's properties can be manipulated to identify spatially tuned cell types and to explore remapping as it relates to alternate information forms such as spatiotemporal coding.DiscussionWe present a feasible, lightweight approach that complements traditional methods. Our findings underscore the potential of the EMD as a powerful tool for enhancing our understanding of remapping in the brain and its implications for spatial navigation, memory studies and beyond.

Representation of the environment by hippocampal populations is known to drift even within a familiar environment, which could reflect gradual changes in single-cell activity or result from averaging across discrete switches of single neurons. Disambiguating these possibilities is crucial, as they each imply distinct mechanisms. Leveraging change point detection and model comparison, we find that CA1 population vectors decorrelate gradually within a session. In contrast, individual neurons exhibit predominantly step-like emergence and disappearance of place fields or sustained changes in within-field firing. The changes are not restricted to particular parts of the maze or trials and do not require apparent behavioral changes. The same place fields emerge, disappear, and reappear across days, suggesting that the hippocampus reuses pre-existing assemblies, rather than forming new fields de novo. Our results suggest an internally driven perpetual step-like reorganization of the neuronal assemblies. [Display omitted] • Hippocampal neurons exhibit representational drift within a session • Step-like switches in individual firing rates underlie gradual population drift • Pre-existing assemblies bias spontaneous (dis)appearance of fields across days Zheng et al. systematically analyze drift in hippocampal place fields and show that, while the population-level representation gradually drifts, the peak firing rates of individual place fields are better described by abrupt changes. The step-like changes are not driven by measured behavioral variables and are biased by the pre-existing assemblies. [ABSTRACT FROM AUTHOR]

Predictive remapping of receptive fields (RFs) is thought to be one of the critical mechanisms for enforcing perceptual stability during eye movements. While RF remapping has been observed in several cortical areas, its role in early visual cortex and its consequences on the tuning properties of neurons have been poorly understood. Here, we track remapping RFs in hundreds of neurons from visual area V2 while subjects perform a cued saccade task. We find that remapping is widespread in area V2 across neurons from all recorded cortical layers and cell types. Furthermore, our results suggest that remapping RFs not only maintain but also transiently enhance their feature selectivity due to untuned suppression. Taken together, these findings shed light on the dynamics and prevalence of remapping in the early visual cortex, forcing us to revise current models of perceptual stability during saccadic eye movements. [Display omitted] • Pre-saccadic remapping is widespread in primate visual area V2 • 70% of neurons remap around 30 ms before saccade onset • Entire cortical columns exhibit remapping • Remapping is accompanied by a transient increase in orientation selectivity Denagamage et al. investigate peri-saccadic receptive field dynamics in primate visual area V2 and find evidence of cortical column-wide predictive remapping. Remapping is accompanied by a transient increase in orientation selectivity. [ABSTRACT FROM AUTHOR]

Environmental enrichment (EE) improves memory, particularly the ability to discriminate similar past experiences. 1,2,3,4,5,6 The hippocampus supports this ability via pattern separation, the encoding of similar events using dissimilar memory representations. 7 This is carried out in the dentate gyrus (DG) and CA3 subfields. 8,9,10,11,12 Upregulation of adult neurogenesis in the DG improves memory through enhanced pattern separation. 1,2,3,4,5,6,11,13,14,15,16 Adult-born granule cells (abGCs) in DG are suggested to contribute to pattern separation by driving inhibition in regions such as CA3, 13,14,15,16,17,18 leading to sparser, nonoverlapping representations of similar events (although a role for abGCs in driving excitation in the hippocampus has also been reported 16). Place cells in the hippocampus contribute to pattern separation by remapping to spatial and contextual alterations to the environment. 19,20,21,22,23,24,25,26,27 How spatial responses in CA3 are affected by EE and input from increased numbers of abGCs in DG is, however, unknown. Here, we investigate the neural mechanisms facilitating improved memory following EE using associative recognition memory tasks that model the automatic and integrative nature of episodic memory. We find that EE-dependent improvements in difficult discriminations are related to increased neurogenesis and sparser memory representations across the hippocampus. Additionally, we report for the first time that EE changes how CA3 place cells discriminate similar contexts. CA3 place cells of enriched rats show greater spatial tuning, increased firing rates, and enhanced remapping to contextual changes. These findings point to more precise and flexible CA3 memory representations in enriched rats, which provides a putative mechanism for EE-dependent improvements in fine memory discrimination. • Environmental enrichment improves discrimination of similar associative memories • EE-dependent memory improvements are related to increased adult neurogenesis • EE results in sparser hippocampal activity • EE increases spatial tuning, firing, and remapping of CA3 place cells Ventura et al. demonstrate that enrichment-dependent increases in adult hippocampal neurogenesis are associated with improved pattern separation in episodic-like memory in rats. Enrichment also results in sparser hippocampal neuronal activity as well as finer spatial tuning and increased remapping in CA3 place cells. [ABSTRACT FROM AUTHOR]

• A second order intersection-based remapping method for cell-centered quantities in two dimensional cylindrical coordinates is proposed. • The remapping method is capable to preserve spherical symmetry when the mesh and mesh moving are symmetric. • The remapping method has good properties such as conservation for mass, momentum and total energy. • The symmetry preserving property and second order accuracy are strictly proved and demonstrated by numerical tests. The importance of preserving physical symmetry in arbitrary Lagrangian-Eulerian (ALE) simulations is well recognized. In the past decades, first order spherical-symmetry-preserving Lagrangian and ALE methods in two-dimensional cylindrical coordinates were developed. And there are also several works about second order spherical-symmetry-preserving cell-centered Lagrangian schemes. The goal of this paper is to develop Second order spherical-symmetry-preserving intersection-based remapping method in two-dimensional cylindrical coordinates. The method is capable to preserve one-dimensional spherical symmetry when the old grid is equiangular polar mesh and the rezoning algorithm only moves points in the radial directions by the same amount for all points with the same spherical radius. The remapping method has second order accuracy almost uniformly (the accuracy drops to first order close to the revolution axis), has good properties such as conservation for mass, momentum and total energy. The symmetry-preserving property and second order accuracy of our new remapping method are proved mathematically and demonstrated by several numerical examples. [ABSTRACT FROM AUTHOR]

The visual system represents objects in a lateralized manner, with contralateral cortical hemispheres responsible for left and right visual hemifields. This organization extends to visual short-term memory (VSTM), as evidenced by electrophysiological indices of VSTM maintenance: contralateral delay activity (CDA) and alpha-band lateralization. However, it remains unclear if VSTM represents object locations in gaze-centered (retinotopic) or screen-centered (spatiotopic) coordinates, especially after eye movements. In two experiments, participants encoded the colors of target objects and made a lateral saccade during the maintenance interval, thereby shifting the object's location on the retina. A non-lateralized probe stimulus was then presented at the new fixation for a change detection task. The CDA maintained lateralization towards the target's original retinotopic location, unaffected by subsequent saccades, and did not invert polarity even when a saccade brought that location into the opposite hemifield. We also found conventional alpha lateralization towards the target's location before a saccade. After a saccade, however, alpha was lateralized towards the screen center regardless of the target's original location, even in a control condition without any memory requirements. This suggests that post-saccadic alpha-band lateralization reflects attentional processes unrelated to memory, while pre- and post-saccade CDA reflect VSTM maintenance in a retinotopic reference frame. • Contralateral delay activity and alpha-band lateralization track spatial locations in short-term memory. • How are these signals updated after eye-movements? • CDA reflect memory maintenance in a retinotopic reference frame. • Alpha-band lateralization reflects attentional processes unrelated to memory. [ABSTRACT FROM AUTHOR]

A behavioral strategy crucial to survival is directed navigation to a goal, such as a food or home location. One potential neural substrate for supporting goal-directed navigation is the parahippocampus, which contains neurons that represent an animal's position, orientation, and movement through the world, and that change their firing activity to encode behaviorally relevant variables such as reward. However, little prior work on the parahippocampus has considered how neurons encode variables during goal-directed navigation in environments that dynamically change. Here, we recorded single units from rat parahippocampal cortex while subjects performed a goal-directed task. The maze dynamically changed goal-locations via a visual cue on a trial-to-trial basis, requiring subjects to use cue-location associations to receive reward. We observed a mismatch-like signal, with elevated neural activity on incorrect trials, leading to rate-remapping. The strength of this remapping correlated with task performance. Recordings during open-field foraging allowed us to functionally define navigational coding for a subset of the neurons recorded in the maze. This approach revealed that head-direction coding units remapped more than other functional-defined units. Taken together, this work thus raises the possibility that during goal-directed navigation, parahippocampal neurons encode error information reflective of an animal's behavioral performance., Competing Interests: AG No competing interests declared, LG Reviewing editor, eLife, (© 2023, Gonzalez and Giocomo.)