Background: Extinction of conditioned fear represents an important mechanism in the treatment of anxiety disorders. Return of fear after successful extinction or exposure therapy in patients with anxiety disorders might be linked to poor temporal or contextual generalization of extinction due to individual differences in brain structural connectivity. The goal of this magnetic resonance imaging study was therefore to investigate the association of context-dependent extinction recall with brain structural connectivity.
Methods: Diffusion-tensor imaging was used to determine the fractional anisotropy as a measure of white matter structural integrity of fiber tracts connecting central brain regions of the fear and extinction circuit (uncinate fasciculus, cingulum). Forty-five healthy men participated in a two-day fear conditioning experiment with fear acquisition in context A and extinction learning in context B on the first day. Extinction recall in the extinction context as well as renewal in the acquisition context and a novel context C took place one day later.
Results: Renewal of conditioned fear (skin conductance responses) in the acquisition context was associated with higher structural integrity of the hippocampal part of the cingulum.
Conclusions: Enhanced structural integrity of the cingulum might be related to stronger hippocampal modulation of the dorsal anterior cingulate cortex, a region important for modulating conditioned fear output by excitatory projections to the amygdala. This finding underpins the crucial role of individual differences in the structural integrity of relevant fiber tracts for context-dependent extinction recall and return of fear after exposure therapy in anxiety disorders.
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http://dx.doi.org/10.1002/hipo.22738 | DOI Listing |
AAPS PharmSciTech
January 2025
Department of Pharmaceutics, School of Pharmaceutical Science, Siksha 'O' Anusandhan University, Bhubaneswar, 751003, Odisha, India.
Transdermal drug delivery (TDD) represents a transformative paradigm in drug administration, offering advantages such as controlled drug release, enhanced patient adherence, and circumvention of hepatic first-pass metabolism. Despite these benefits, the inherent barrier function of the skin, primarily attributed to the stratum corneum, remains a significant impediment to the efficient permeation of therapeutic agents. Recent advancements have focused on macromolecular-assisted permeation enhancers, including carbohydrates, lipids, amino acids, nucleic acids, and cell-penetrating peptides, which modulate skin permeability by transiently altering its structural integrity.
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January 2025
Department of Anesthesiology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563000, China.
As one of the most commonly used general anesthetics (GAs) in surgery, numerous studies have demonstrated the detrimental effects of sevoflurane exposure on myelination in the developing and elderly brain. However, the impact of sevoflurane exposure on intact myelin structure in the adult brain is barely discovered. Here, we show that repeated sevoflurane exposure, but not single exposure, causes hypomyelination and abnormal ultrastructure of myelin sheath in the prefrontal cortex (PFC) of adult male mice, which is considered as a critical brain region for general anesthesia mediated consciousness change.
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January 2025
University of Chinese Academy of Sciences, 100049, Beijing, China.
The stability criterion based on the characterization of rock masses can be used to advance deep underground engineering projects. A key geomechanical criterion in geotechnical engineering is rock quality designation (RQD), which assesses risk for engineering design success criteria. Time, cost, and credibility constraints make it difficult to accurately estimate RQD.
View Article and Find Full Text PDFSci Bull (Beijing)
December 2024
Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. Electronic address:
Tailored design of organic linkers or metal nodes can introduce desirable functionalities into metal-organic cages (MOCs), significantly expanding their potential applications. In this study, we present a viable approach for engineering acyl-type metal nodes to create interior oxygen-rich sites within MOCs, enabling specific recognition of metal ions, including radioactive contaminants, while maintaining the structural integrity of the MOCs. A novel MOC featuring a uranyl-sealed calix[4]resorcinarene (C[4]R)-based multisite cavity, referred to as UOC, is synthesized as a prototype.
View Article and Find Full Text PDFActa Biomater
January 2025
Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States; School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, Storrs, CT, United States. Electronic address:
In this study we investigate the mechanics of type II collagen fibrils, an essential structural component in many load-bearing tissues including cartilage. Although type II collagen plays a crucial role in maintaining tissue integrity, the stress-stretch and failure response of type II collagen fibrils in tension is not established in the current mechanics literature. To address this knowledge gap, we conducted tensile tests on isolated collagen networks from articular cartilage and established a validated constitutive model for type II collagen fibril.
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