Linear Self-Motion Cues Support the Spatial Distribution and Stability of Hippocampal Place Cells

The vestibular system provides a crucial component of place-cell and head-direction cell activity [1-7]. Otolith signals are necessary for head-direction signal stability and associated behavior [8, 9], and the head-direction signal's contribution to parahippocampal spatial representations [10-14] suggests that place cells may also require otolithic information. Here, we demonstrate that self-movement information from the otolith organs is necessary for the development of stable place fields within and across sessions. Place cells in otoconia-deficient tilted mice showed reduced spatial coherence and formed place fields that were located closer to environmental boundaries, relative to those of control mice. These differences reveal an important otolithic contribution to place-cell functioning and provide insight into the cognitive deficits associated with otolith dysfunction

Acetylcholine Contributes to Head Direction Cell Stability During Path Integration and Landmark Navigation

Perceived directional heading is represented in the brain by head direction (HD) cells, which fire rapidly when the head is pointed in one direction and become virtually silent when the head is pointed in all other directions. The HD signal is dominantly controlled by the position of visual landmarks, but can be maintained by path integration when familiar landmarks are not available. The neural mechanism(s) that allow path integration to maintain the HD signal have not been investigated, but a possible component of this mechanism is acetylcholine, given that selective cholinergic lesions impair path integration-based navigation. To test this, we recorded HD cell activity from the anterodorsal thalamus while rats foraged for food within a cylinder, or navigated within a dual chamber apparatus, after systemic injection of saline or atropine sulfate. In the cylinder, a prominent cue card served as the sole landmark for a standard session, after which the cue was removed for a no-cue session. Saline or atropine sulfate was then injected, and a second no-cue session was conducted, followed by standard, 90° cue rotation, standard, and no-cue sessions. During the first no-cue session after injection, some cells in atropine-treated rats showed slightly more drift in preferred firing direction (PFD) than control cells, but otherwise appeared to be unaffected by atropine. With the cue rotated 90º, 10 of the 19 (53%) cells in atropine-treated rats and 12 of the 17 (71%) control cells shifted within ± 30° of 90º. In the dual chamber apparatus, rats walked from a familiar cylinder to a novel rectangle via an alleyway, and then returned to the familiar cylinder. Control HD cells (n = 7) showed a slight PFD shift as the rat entered the novel rectangle (mean absolute shift = 17.14 ± 3.80°, range = -30 to 12°), suggesting the HD signal was maintained relatively well between arenas by path integration; upon return, the PFD returned to that of the first session (mean absolute shift = 5.14 ± 1.56°, range = -12 to 6°). In contrast, 7 of the 9 HD cells in atropine-treated rats (78%) showed greater PFD shifts between the familiar cylinder and novel rectangle (mean absolute shift = 86.00 ± 12.17°, angular shift range = -102 to 114°) and between the first and last sessions in the familiar cylinder (mean absolute shift = 24.00 ± 10.16°, angular shift range = 0 to -72°); 2 of the 9 cells (22%) showed considerable PFD drift during the novel rectangle or return cylinder sessions. Thus, acetylcholine is not critical for normal HD cell activity within a familiar environment, but facilitates the stability of the HD signal during both path integration and landmark navigation

Anxiety and Its Impact on Memory

From influences on our memories of common words to even eyewitness testimonies, anxiety can shape our view of the world (Amir et al., 1996). Our research attempted to show a relationship between anxiety and its effects as an impact on memory as is supported by the Theory of Attentional Control (Eysenck & Calvo, 1992). A video from Simons’ and Chabris’ (1999) study on Inattentional Blindness was used to assess whether anxiety is adaptive or maladaptive to functions of our memory. Our study did not find significance regarding the impact of anxiety on memory. However, the relevance and interest of studies on memory and arousal continues to escalate through the years

Climatic versus biotic constraints on carbon and water fluxes in seasonally drought-affected ponderosa pine ecosystems

We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE

Task demands influence search strategy selection in otoconia-deficient mice

Introduction: The vestibular system plays a crucial role in visual and non-visual navigation. Our recent study found that signals from the otolith organs are necessary for mice’s use of distal visual cues to guide navigation to an invisible goal. Somewhat surprisingly, however, performance was not significantly impaired on some spatial tasks (e.g., Barnes maze reference memory task), questioning the role of otolith signals in visual navigation. Methods: We report the results of several additional tests of reference memory performance and search strategy use on two versions of the Barnes maze, in an attempt to establish further understanding of the otolithic contribution to visual navigation. Results: On a small Barnes maze, control mice preferentially used the efficient “spatial” search strategy by the last (8th) day of training, whereas otoconia-deficient tilted mice failed to show this preference. On the subsequent probe trial, both groups showed a preference for the former goal location, suggesting otolith signals are not necessary for the use of distal cues to triangulate the animal’s position, relative to distal cues. On a large Barnes maze, both control and tilted mice used a spatial search strategy most frequently by the last (4th) day of training and showed a preference for the former goal location on the subsequent probe trial. Discussion: Overall, these results suggest that otolith dysfunction in mice is associated with subtle navigational deficits that became apparent on the small maze but that were less apparent on the large maze. It is possible that these navigational differences resulted from the greater distance between start and goal locations of the large maze, relative to the small maze. Alternatively, the large maze’s greater distance between the goal and potential alternatives may have facilitated more accurate place recognition. This article was published Open Access through the CCU Libraries Transformative Agreement Program. The article was first published in Frontiers in Neurology: 10.3389/fneur.2025.153170

Supplementary data for article: Ruan, Y.; Taha, H. A.; Yoder, R. J.; Maslak, V.; Hadad, C. M.; Bađić, J. D. The Prospect of Selective Recognition of Nerve Agents with Modular Basket-like Hosts. A Structure-Activity Study of the Entrapment of a Series of Organophosphonates in Aqueous Media. Journal of Physical Chemistry. Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophys 2013, 117 (11), 3240–3249. https://doi.org/10.1021/jp401841w

Supporting information for: [https://doi.org/10.1021/jp401841w]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1619

Outcomes After Definitive Treatment for Cutaneous Angiosarcomas of the Face and Scalp: Reevaluating the Role of Surgery and Radiation Therapy

INTRODUCTION: We investigated outcomes and prognostic factors for patients treated for cutaneous angiosarcoma (CA). METHODS: We conducted a retrospective review of patients treated for CA of the face and scalp from 1962 to 2019. All received definitive treatment with surgery, radiation (RT), or a combination (S-XRT). The Kaplan-Meier method was used to estimate outcomes. Multivariable analyses were conducted using the Cox proportional hazards model. RESULTS: For the 143 patients evaluated median follow-up was 33 months. Five-year LC was 51% and worse in patients with tumors \u3e5 cm, multifocal tumors, those treated pre-2000, and with single modality therapy (SMT). These remained associated with worse LC on multivariable analysis. The 5-year disease-specific survival (DSS) for the cohort was 56%. Tumor size \u3e5 cm, non-scalp primary site, treatment pre-2000, and SMT were associated with worse DSS. CONCLUSION: Large or multifocal tumors are negative prognostic factors in patients with head and neck CA. S-XRT improved outcomes

Supplementary data for article: Ruan, Y.; Taha, H. A.; Yoder, R. J.; Maslak, V.; Hadad, C. M.; Bađić, J. D. The Prospect of Selective Recognition of Nerve Agents with Modular Basket-like Hosts. A Structure-Activity Study of the Entrapment of a Series of Organophosphonates in Aqueous Media. Journal of Physical Chemistry. Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophys 2013, 117 (11), 3240–3249. https://doi.org/10.1021/jp401841w

Supporting information for: [https://doi.org/10.1021/jp401841w]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1619

Molecular Phylogeny and Biogeography of the Native Rodents of Madagascar (Muridae: Nesomyinae): A Test of the Single-Origin Hypothesis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72349/1/j.1096-0031.1999.tb00267.x.pd