Frontiers in Neuroanatomy最新文献

The extracellular matrix (ECM) is a non-cellular and gelatinous component of tissues, rich in proteins and proteoglycans, that provides information about the environment, forms a reservoir of trophic factors and regulates cell behavior by binding and activating cell surface receptors. This important network acts as a scaffold for tissues and organs throughout the body, playing an essential role in their structural and functional integrity. It is essential for cells to connect and communicate with each other and play an active role in intracellular signaling. Due to these properties, in recent decades the potential of the extracellular matrix in tissue engineering has begun to be explored with the aim of developing innovative biomaterials to be used in regenerative medicine. This review will first outline the components of the extracellular matrix in the peripheral nerve, followed by an exploration of its role in the regeneration process after injury, with a focus on the mechanisms underlying its interactions with nerve cells. Qualitative and quantitative methods used for extracellular matrix analysis will be described, and finally an overview will be given of recent advances in nerve repair strategies that exploit the potential of the extracellular matrix to enhance regeneration, highlighting the critical issues of extracellular matrix molecule use and proposing new directions for future research.

Introduction: Identifying long-term changes in retinal structure and vasculature is essential for interpreting in vivo imaging techniques such as optical coherence tomography (OCT) and OCT angiography (OCTA) in retinal diseases. We characterized long-term alterations in vasculature, retinal structure, and glial cells by combining immunohistochemistry (IHC) with OCT and OCTA in a murine model of retinitis pigmentosa.

Methods: Transversal retinal sections and wholemount retinas from C57BL/6J and rd10 mice, aged P20 to 24 months, were immunostained to evaluate retinal structure, glial cells, retinal pigment epithelium (RPE), and the vascular network. OCT and OCTA images from the central retina were also analyzed.

Results: Significant retinal remodeling in the inner retina occurs over time and was detectable from 4 months using IHC and from 6 months using OCT. Remodeling was characterized by glial activation (reactive gliosis) and the formation of hyperreflective columns, which contain Müller cells, activated microglia, RPE, and choroidal vessels in the late stages. No significant differences were observed between OCTA and IHC vascular density of the superficial vascular plexus (SVP) and deep capillary plexus (DCP) in rd10 mice at any time points, except at 2 months (SVP, p = 0.009; DCP, p = 0.001). This seems a critical stage, suggesting differing rates of blood flow reduction and structural vessel loss. A peak of vascular degeneration in the SVP of rd10 mice was detected by OCTA between 2 and 6 months (p = 0.003), but not by IHC. Vascular degeneration peak of DCP in rd10 was observed between P20 and 2 months using OCTA (p < 0.0001), and between 2 and 6 months using IHC (p = 0.003).

Conclusion: Overall, OCTA and IHC yielded comparable long-term vascular density results, supporting OCTA as a reliable, non-invasive tool for studying vessel degeneration in animal models. Therefore, longitudinal in vivo evaluation of retinal remodeling through OCT and OCTA constitutes a valuable methodology for investigating disease mechanisms and guiding therapeutic development.

Santiago Ramón y Cajal's pioneering work laid the foundations for modern neuroscience and continues to impact the development of artificial intelligence, particularly deep learning. His neuron theory, the principle of dynamic polarization, and his insights into brain plasticity and network organization have significantly influenced both our understanding of the nervous system and the design of artificial neural networks. This article reviews Cajal's key contributions, explores their role in the evolution of AI, and emphasizes the enduring links between neuroscience and machine learning in the digital era.

Introduction: The olfactory system acts as an interface between the environment and the brain. Its direct neural connection makes it a target for xenobiotics and a suitable model for studying olfactory dysfunction and related neurotoxic effects. This study aimed to characterize an animal model of olfactory dysfunction induced by nose-to-brain (NTB) delivery of vanadium pentoxide (V₂O₅).

Methods: Rats received 182 or 273 μg intranasally, thrice weekly over 4 weeks, followed by behavioral, histological, and biochemical analysis of the olfactory epithelium (OE), olfactory bulbs (OBs), and hippocampus.

Results: Behavioral tests showed significant olfactory deficits, longer latencies, and reduced investigation times in exposed groups. Histological analysis revealed coagulative necrosis in the OE, disrupted cellular organization, reduced number and size of OB glomeruli, and hippocampal neuronal loss with gliosis. Immunohistochemistry revealed increased proliferating cell nuclear antigen (PCNA) expression in the OE, dopaminergic neuron loss and astroglial proliferation in the OB, and hippocampal astroglial proliferation at the highest dose. Myelin basic protein (MBP) expression remained unchanged. Oxidative stress markers were largely unaltered, except for increased superoxide dismutase (SOD) in OBs and glutathione S-transferase (GST) in the hippocampus, especially at the high dose.

Discussion: The results reveal dose-dependent vanadium-induced neurotoxicity in the olfactory system. The higher dose induced pronounced structural damage, neuroinflammation, and oxidative stress, resulting in olfactory and cognitive impairments relevant to advanced olfactory dysfunction and neurodegeneration. The lower dose induced milder yet significant effects, supporting its use in early-stage dysfunction studies. This NTB-based model offers a valuable tool for investigating olfactory dysfunction mechanisms in toxicological and neurodegenerative contexts.

This article explores the complex and ultimately unsuccessful Nobel Prize trajectories of Oskar (1870-1959) and Cécile Vogt (1875-1962), as well as their ongoing scientific legacy. Their legacy sheds light on the background to the decision from different perspectives. Despite multiple nominations, the couple never received the Nobel Prize in Physiology or Medicine. Drawing upon archival sources from the Nobel Forum and the Vogt Archive in Düsseldorf, we reconstruct the history of their candidacies, the reasons why they were proposed, and those behind the committee's repeated rejections. Their work on cyto- and myeloarchitectonics, the functional anatomy of the basal ganglia, and structure-function relationships in the cerebral cortex earned them international recognition. However, the Nobel Committee remained unconvinced, often citing issues of scientific priority, insufficient novelty, and the controversial nature of some of their claims. Despite their exclusion from the prize, the Vogts' research shaped the development of brain science across Europe and beyond, influencing later Nobel laureates and contributing to foundational concepts in neuroanatomy and -physiology. Their case invites reflection on the historical contingencies of scientific recognition and the shifting criteria for what counts as a "discovery" worthy of the Nobel Prize.

Comparative studies on the forebrain across different model organisms are necessary to investigate the origin and degree of evolutionary conservation of this brain region and its derivatives. The catshark Scyliorhinus canicula has become a reliable model representative of cartilaginous fishes (Chondrichthyans), the oldest divergent lineage of extant gnathostomes (jawed vertebrates). Previous studies on the chemoarchitecture, connectivity, and development of the subpallium of S. canicula revealed the existence of subdivisions with an embryological origin and genetic specification similar to those of tetrapods, supporting homology with their basal ganglia and certain amygdaloid components. To better understand the evolutionary origin of these subpallial components, we present here a summary of the main neuroanatomical, chemoarchitectural, and developmental features of the area superficialis basalis of S. canicula, a nuclear aggrupation of the basal forebrain of all Chondrichthyans that has been related to the basal ganglia and the amygdala. Particular emphasis has been placed on characterizing the tyrosine hydroxylase-positive components of the subpallium to discern their involvement in the structural organization of putative basal ganglia homologs in the catshark. We propose a new interpretation that considers the area superficialis basalis as the central part of a subpallial complex formed also by its neighboring territories, where the basic components of the basal ganglia and the amygdala of gnathostomes would be integrated.

Animals use different communication modalities for social interactions, often showing sensory adaptations linked to their preferred signaling system. How such adaptations affect individual processing centers usually remains elusive due to interspecies differences. One system in which such adaptations can be investigated are Synodontis catfish. Synodontids generally use acoustic signals for social communication, but in some species, they generate electric signals. This allows to investigate adaptations of networks associated with social signal detection in closely related species. We investigated potential sensory adaptations in two Synodontis species (Synodontis grandiops - SG and Synodontis nigriventris - SN) with different communication channels. We tested their behavioral preferences toward different sensory modalities and found strong preferences for conspecifics. To investigate potential adaptations at the cellular level, we focused on the torus semicircularis (TS), a major midbrain sensory hub for auditory and electric sensory processing. We found an increase in projections from the anterior tuberal nucleus (AT) to the lateral TS (TSl, which processes electrosensory information) in SN, but no difference in the projections from the central TS (TSc) to AT in either species. An enhanced density of calcium binding proteins in the TSl was found only in SN. As electrocommunication is a derived communication channel in Synodontis, our findings suggest that a shift to electric communication may have led to (i) stronger projections to and from sensory regions, and (ii) a change in neurochemical profile, which together might facilitate social signal detection.

Introduction: The gut microbiota plays a critical role in regulating brain structure and function via the microbiota-gut-brain axis. Antibiotic-induced gut dysbiosis (AIGD) has been linked to neuroanatomical changes and cognitive deficits. However, its impact on neuronal morphology in layer II of the medial entorhinal cortex (mECII), a region central to spatial memory, remains poorly understood. This study examines how AIGD affects dendritic architecture in mECII stellate and pyramidal island cells.

Methods: Mice received a broad-spectrum oral antibiotic cocktail to induce AIGD. Gut microbiota composition was analyzed using 16S rRNA sequencing. Golgi-stained neurons in mECII were assessed for dendritic complexity via Sholl analysis. Iba1 staining evaluated microglial activation in mECII. Intestinal sections were stained with NeuN and CD8 to assess enteric neuron density and inflammation. Microbial abundance was correlated with dendritic parameters.

Results: AIGD resulted in significant dysbiosis, including depletion of butyrate-producing taxa (Roseburia, Faecalibacterium) and enrichment of proinflammatory bacteria (Clostridium, Salmonella, Enterococcus). Stellate cells showed marked dendritic atrophy, while pyramidal island cells were unaffected. Dendritic complexity positively correlated with Roseburia hominis and negatively with Enterococcus faecalis. No microglial activation was detected in mECII, but CD8 + T-cell infiltration increased in the gut without changes in NeuN-labeled enteric neurons.

Discussion: These findings suggest AIGD selectively alters mECII stellate cell morphology through peripheral immune signaling or microbial metabolites, independent of local microglial activation. This study highlights the role of gut microbiota in shaping neuronal architecture and supports microbiome-targeted strategies to counteract dysbiosis-associated neuroanatomical changes.

Even though bats are the second most speciose group of mammals, neuroanatomical studies of their hippocampus are rare, particularly of small echolocating bats. Here, we provide a qualitative and quantitative neuroanatomical analysis of the hippocampus of small echolocating bats (Phyllostomidae and Vespertilionidae). Calcium-binding proteins revealed species- and family-specific patterns for calbindin and calretinin. Interneuron staining for both proteins was very rare in phyllostomids, while calretinin marked subpopulations of CA3 pyramidal neurons in both families. Parvalbumin expression was consistent across bats and similar to other species. A unique calretinin-positive calbindin-negative zone was observed at the superficial boundary of the CA3 pyramidal cell layer in phyllostomid bats. This zone defined a gap between pyramidal cells and the zinc-positive mossy fibers. We hypothesize that this gap might either stem from calretinin-positive afferents displacing the zinc-positive mossy fiber boutons, or from a complete segregation of neurochemically distinct mossy boutons. Furthermore, we observed a distinct dorsoventral shift in the length of the upper and lower blade of the granule cell layer in all species. In terms of hippocampal neuron numbers, bats were characterized by a rather small granule cell and subicular neuron population, but a well-developed CA3. In a correspondence analysis, preferred diet segregated phyllostomids into a hilus-dominant omnivorous and frugivorous species group, and a subiculum-dominant group containing vampire bats and nectivorous species. Although the two families overlapped considerably, the cellular composition of the phyllostomid hippocampus can be described as output dominant, while in vespertilionids neuron populations on the hippocampal input side are more dominant. Neuroanatomical and ecological variability and unique traits within echolocating bats as shown here can provide a rich source for investigating structure-function relationships.