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Neural Regeneration Research Feb 2025Microglia are present throughout the central nervous system and are vital in neural repair, nutrition, phagocytosis, immunological regulation, and maintaining neuronal...
Microglia are present throughout the central nervous system and are vital in neural repair, nutrition, phagocytosis, immunological regulation, and maintaining neuronal function. In a healthy spinal cord, microglia are accountable for immune surveillance, however, when a spinal cord injury occurs, the microenvironment drastically changes, leading to glial scars and failed axonal regeneration. In this context, microglia vary their gene and protein expression during activation, and proliferation in reaction to the injury, influencing injury responses both favorably and unfavorably. A dynamic and multifaceted injury response is mediated by microglia, which interact directly with neurons, astrocytes, oligodendrocytes, and neural stem/progenitor cells. Despite a clear understanding of their essential nature and origin, the mechanisms of action and new functions of microglia in spinal cord injury require extensive research. This review summarizes current studies on microglial genesis, physiological function, and pathological state, highlights their crucial roles in spinal cord injury, and proposes microglia as a therapeutic target.
PubMed: 38819048
DOI: 10.4103/NRR.NRR-D-23-02044 -
Scientific Reports May 2024Sex hormones affect structural and functional plasticity in the rodent hippocampus. However, hormone levels not only differ between males and females, but also fluctuate...
Sex hormones affect structural and functional plasticity in the rodent hippocampus. However, hormone levels not only differ between males and females, but also fluctuate across the female estrous cycle. While sex- and cycle-dependent differences in dendritic spine density and morphology have been found in the rodent CA1 region, but not in the CA3 or the dentate gyrus, comparable structural data on CA2, i.e. the hippocampal region involved in social recognition memory, is so far lacking. In this study, we, therefore, used wildtype male and female mice in diestrus or proestrus to analyze spines on dendritic segments from identified CA2 neurons. In basal stratum oriens, we found no differences in spine density, but a significant shift towards larger spine head areas in male mice compared to females. Conversely, in apical stratum radiatum diestrus females had a significantly higher spine density, and females in either cycle stage had a significant shift towards larger spine head areas as compared to males, with diestrus females showing the larger shift. Our results provide further evidence for the sexual dimorphism of hippocampal area CA2, and underscore the importance of considering not only the sex, but also the stage of the estrous cycle when interpreting morphological data.
Topics: Animals; Male; Female; Dendritic Spines; Mice; Estrous Cycle; CA2 Region, Hippocampal; Sex Characteristics; Neurons
PubMed: 38806649
DOI: 10.1038/s41598-024-62951-x -
Cureus Apr 2024Introduction ChatGPT (OpenAI Incorporated, Mission District, San Francisco, United States) is an artificial intelligence (AI) chatbot with advanced communication skills...
Introduction ChatGPT (OpenAI Incorporated, Mission District, San Francisco, United States) is an artificial intelligence (AI) chatbot with advanced communication skills and a massive knowledge database. However, its application in medicine, specifically in neurolocalization, necessitates clinical reasoning in addition to deep neuroanatomical knowledge. This article examines ChatGPT's capabilities in neurolocalization. Methods Forty-six text-based neurolocalization case scenarios were presented to ChatGPT-3.5 from November 6th, 2023, to November 16th, 2023. Seven neurosurgeons evaluated ChatGPT's responses to these cases, utilizing a 5-point scoring system recommended by ChatGPT, to score the accuracy of these responses. Results ChatGPT-3.5 achieved an accuracy score of 84.8% in generating "completely correct" and "mostly correct" responses. ANOVA analysis suggested a consistent scoring approach between different evaluators. The mean length of the case text was 69.8 tokens (SD 20.8). Conclusion While this accuracy score is promising, it is not yet reliable for routine patient care. We recommend keeping interactions with ChatGPT concise, precise, and simple to improve response accuracy. As AI continues to evolve, it will hold significant and innovative breakthroughs in medicine.
PubMed: 38803743
DOI: 10.7759/cureus.59143 -
EMBO Molecular Medicine May 2024In the injured brain, new neurons produced from endogenous neural stem cells form chains and migrate to injured areas and contribute to the regeneration of lost neurons....
In the injured brain, new neurons produced from endogenous neural stem cells form chains and migrate to injured areas and contribute to the regeneration of lost neurons. However, this endogenous regenerative capacity of the brain has not yet been leveraged for the treatment of brain injury. Here, we show that in healthy brain chains of migrating new neurons maintain unexpectedly large non-adherent areas between neighboring cells, allowing for efficient migration. In instances of brain injury, neuraminidase reduces polysialic acid levels, which negatively regulates adhesion, leading to increased cell-cell adhesion and reduced migration efficiency. The administration of zanamivir, a neuraminidase inhibitor used for influenza treatment, promotes neuronal migration toward damaged regions, fosters neuronal regeneration, and facilitates functional recovery. Together, these findings shed light on a new mechanism governing efficient neuronal migration in the adult brain under physiological conditions, pinpoint the disruption of this mechanism during brain injury, and propose a promising therapeutic avenue for brain injury through drug repositioning.
PubMed: 38789599
DOI: 10.1038/s44321-024-00073-7 -
Biomolecules May 2024During the first and second stages of postnatal development, neocortical neurons exhibit a wide range of spontaneous synchronous activity (SSA). Towards the end of the...
During the first and second stages of postnatal development, neocortical neurons exhibit a wide range of spontaneous synchronous activity (SSA). Towards the end of the second postnatal week, the SSA is replaced by a more sparse and desynchronized firing pattern. The developmental desynchronization of neocortical spontaneous neuronal activity is thought to be intrinsically generated, since sensory deprivation from the periphery does not affect the time course of this transition. The extracellular protein reelin controls various aspects of neuronal development through multimodular signaling. However, so far it is unclear whether reelin contributes to the developmental desynchronization transition of neocortical neurons. The present study aims to investigate the role of reelin in postnatal cortical developmental desynchronization using a conditional reelin knockout (Reln) mouse model. Conditional reelin deficiency was induced during early postnatal development, and Ca recordings were conducted from organotypic cultures (OTCs) of the somatosensory cortex. Our results show that both wild type (wt) and Reln exhibited an SSA pattern during the early postnatal week. However, at the end of the second postnatal week, wt OTCs underwent a transition to a desynchronized network activity pattern, while Reln activity remained synchronous. This changing activity pattern suggests that reelin is involved in regulating the developmental desynchronization of cortical neuronal network activity. Moreover, the developmental desynchronization impairment observed in Reln was rescued when Reln OTCs were co-cultured with wt OTCs. Finally, we show that the developmental transition to a desynchronized state at the end of the second postnatal week is not dependent on glutamatergic signaling. Instead, the transition is dependent on GABAR and GABAR signaling. The results suggest that reelin controls developmental desynchronization through GABAR and GABAR signaling.
Topics: Reelin Protein; Animals; Mice; Neocortex; Mice, Knockout; Nerve Tissue Proteins; Serine Endopeptidases; Extracellular Matrix Proteins; Cell Adhesion Molecules, Neuronal; Neurons; Nerve Net; Somatosensory Cortex
PubMed: 38786001
DOI: 10.3390/biom14050593 -
Biomolecules Apr 2024In the present study, we conducted a scoping review to provide an overview of the existing literature on the carbocyanine dye DiI, in human neuroanatomical tract... (Review)
Review
In the present study, we conducted a scoping review to provide an overview of the existing literature on the carbocyanine dye DiI, in human neuroanatomical tract tracing. The PubMed, Scopus, and Web of Science databases were systematically searched. We identified 61 studies published during the last three decades. While studies incorporated specimens across human life from the embryonic stage onwards, the majority of studies focused on adult human tissue. Studies that utilized peripheral nervous system (PNS) tissue were a minority, with the majority of studies focusing on the central nervous system (CNS). The most common topic of interest in previous tract tracing investigations was the connectivity of the visual pathway. DiI crystals were more commonly applied. Nevertheless, several studies utilized DiI in a paste or dissolved form. The maximum tracing distance and tracing speed achieved was, respectively, 70 mm and 1 mm/h. We identified studies that focused on optimizing tracing efficacy by varying parameters such as fixation, incubation temperature, dye re-application, or the application of electric fields. Additional studies aimed at broadening the scope of DiI use by assessing the utility of archival tissue and compatibility of tissue clearing in DiI applications. A combination of DiI tracing and immunohistochemistry in double-labeling studies have been shown to provide the means for assessing connectivity of phenotypically defined human CNS and PNS neuronal populations.
Topics: Humans; Neuroanatomical Tract-Tracing Techniques; Carbocyanines; Central Nervous System; Peripheral Nervous System; Fluorescent Dyes
PubMed: 38785943
DOI: 10.3390/biom14050536 -
Journal of Veterinary Internal Medicine May 2024Neurocandidiasis is systemic candidiasis with central nervous system involvement. This case report describes the clinical presentation, diagnostic test results, and...
Neurocandidiasis is systemic candidiasis with central nervous system involvement. This case report describes the clinical presentation, diagnostic test results, and histopathology of a dog with neurocandidiasis. A 3-year-old German shepherd dog was presented for a 3-day history of abnormal mentation, neck pain, and ataxia. Magnetic resonance imaging (MRI) scan of the brain revealed multifocal, small, round, intra-axial lesions within the forebrain. Examination of the cerebrospinal fluid revealed severe neutrophilic inflammation. Extensive testing for infectious diseases was negative. The dog was administered immunosuppressive doses of corticosteroids. The dog's clinical signs improved transiently but got worse 12 days after starting the treatment. Repeat MRI scan revealed multiple, intra-axial, target-like nodular lesions scattered throughout the brain parenchyma. In the temporal muscles, nodules were seen. Cytology of the fine needle aspirates of the nodules in the temporal muscles revealed a neutrophilic inflammation with hyalohyphomycosis. Postmortem examination was compatible with a severe systemic fungal infection. Candida albicans was isolated from the brain, kidney, and heart.
PubMed: 38769641
DOI: 10.1111/jvim.17093 -
PLoS Biology May 2024Neurons responding during action execution and action observation were discovered in the ventral premotor cortex 3 decades ago. However, the visual features that drive...
Neurons responding during action execution and action observation were discovered in the ventral premotor cortex 3 decades ago. However, the visual features that drive the responses of action observation/execution neurons (AOENs) have not been revealed at present. We investigated the neural responses of AOENs in ventral premotor area F5c of 4 macaques during the observation of action videos and crucial control stimuli. The large majority of AOENs showed highly phasic responses during the action videos, with a preference for the moment that the hand made contact with the object. They also responded to an abstract shape moving towards but not interacting with an object, even when the shape moved on a scrambled background, implying that most AOENs in F5c do not require the perception of causality or a meaningful action. Additionally, the majority of AOENs responded to static frames of the videos. Our findings show that very elementary stimuli, even without a grasping context, are sufficient to drive responses in F5c AOENs.
Topics: Animals; Motor Cortex; Photic Stimulation; Neurons; Male; Macaca mulatta; Visual Perception; Macaca
PubMed: 38768251
DOI: 10.1371/journal.pbio.3002358 -
European Journal of Histochemistry : EJH May 2024Previous studies on the granular layer of the cerebellar cortex have revealed a wide distribution of different subpopulations of less-known large neuron types, called... (Review)
Review
Previous studies on the granular layer of the cerebellar cortex have revealed a wide distribution of different subpopulations of less-known large neuron types, called "non-traditional large neurons", which are distributed in three different zones of the granular layer. These neuron types are mainly involved in the formation of intrinsiccircuits inside the cerebellar cortex. A subpopulation of these neuron types is represented by the synarmotic neuron, which could play a projective role within the cerebellar circuitry. The synarmotic neuron cell body map within the internal zone of the granular layer or in the subjacent white substance. Furthermore, the axon crosses the granular layer and runs in the subcortical white substance, to reenter in an adjacent granular layer, associating two cortico-cerebellar regions of the same folium or of different folia, or could project to the intrinsic cerebellar nuclei. Therefore, along with the Purkinje neuron, the traditional projective neuron type of the cerebellar cortex, the synarmotic neuron is candidate to represent the second projective neuron type of the cerebellar cortex. Studies of chemical neuroanatomy evidenced a predominant inhibitory GABAergic nature of the synarmotic neuron, suggesting that it may mediate an inhibitory GABAergic output of cerebellar cortex within cortico-cortical interconnections or in projections towards intrinsic cerebellar nuclei. On this basis, the present minireview mainly focuses on the morphofunctional and neurochemical data of the synarmotic neuron, and explores its potential involvement in some forms of cerebellar ataxias.
Topics: Cerebellar Cortex; Animals; Humans; Neurons; GABAergic Neurons
PubMed: 38766720
DOI: 10.4081/ejh.2024.3954 -
Parkinson's Disease 2024Heightened trait impulsivity in both subclinical and pathological senses is becoming increasingly recognised in Parkinson's disease (PD). Impulsive behaviours and... (Review)
Review
Heightened trait impulsivity in both subclinical and pathological senses is becoming increasingly recognised in Parkinson's disease (PD). Impulsive behaviours and impulse control disorders (ICDs) are a consequence of perturbation to the rewards pathway leading individuals to conduct activities in a repetitive, excessive, and maladaptive fashion. Commonly linked to PD, heightened trait impulsivity has been found to primarily manifest in the forms of hypersexuality, pathological gambling, compulsive shopping, and binge eating, all of which may significantly impact social and financial standing. Subsequent burden to quality of life for both individuals with PD and caregivers are common. Although risk factors and indicators for ICDs in PD are currently lacking, it is recognised that the condition is often precipitated by dopamine replacement therapies, primarily dopamine agonist administration. While this nonmotor symptom is being increasingly diagnosed in PD populations, it remains relatively elusive in comparison to its motor counterparts. Through discussion of impulsivity characteristics, neuroanatomy, and neurochemistry, in addition to reviewing existing research on the potential contributing factors to impulsivity in PD, this review highlights impulsivity as a significant and detrimental PD symptom. Thus, emphasising the imperative need to establish efficacious diagnostic tools and treatments.
PubMed: 38766569
DOI: 10.1155/2024/8770997