Cortical Regions Research Articles

The strength of anticipated distractors shapes EEG alpha and theta oscillations in a Working Memory task

Working Memory (WM) requires maintenance of task-relevant information and suppression of task-irrelevant/distracting information. Alpha and theta oscillations have been extensively investigated in relation to WM. However, studies that examine both theta and alpha bands in relation to distractors, encompassing not only power modulation but also connectivity modulation, remain scarce. Here, we depicted, at the EEG-source level, the increase in power and connectivity in theta and alpha bands induced by strong relative to weak distractors during a visual Sternberg-like WM task involving the encoding of verbal items. During retention, a strong or weak distractor was presented, predictable in time and nature. Analysis focused on the encoding and retention phases before distractor presentation. Theta and alpha power were computed in cortical regions of interest, and connectivity networks estimated via spectral Granger causality and synthetized using in/out degree indices. The following modulations were observed for strong vs. weak distractors. In theta band during encoding, the power in frontal regions increased, together with frontal-to-frontal and bottom-up occipital-to-temporal-to-frontal connectivity; even during retention, bottom-up theta connectivity increased. In alpha band during retention, but not during encoding, the power in temporal-occipital regions increased, together with top-down frontal-to-occipital and temporal-to-occipital connectivity. From our results, we postulate a proactive cooperation between theta and alpha mechanisms: the first would mediate enhancement of target representation both during encoding and retention, and the second would mediate increased inhibition of sensory areas during retention only, to suppress the processing of imminent distractor without interfering with the processing of ongoing target stimulus during encoding.

White matter structural bases for phase accuracy during tapping synchronization.

We determined the intersubject association between the rhythmic entrainment abilities of human subjects during a synchronization-continuation tapping task (SCT) and the macro- and microstructural properties of their superficial (SWM) and deep (DWM) white matter. Diffusion-weighted images were obtained from 32 subjects who performed the SCT with auditory or visual metronomes and five tempos ranging from 550 to 950 ms. We developed a method to determine the density of short-range fibers that run underneath the cortical mantle, interconnecting nearby cortical regions (U-fibers). Notably, individual differences in the density of U-fibers in the right audiomotor system were correlated with the degree of phase accuracy between the stimuli and taps across subjects. These correlations were specific to the synchronization epoch with auditory metronomes and tempos around 1.5 Hz. In addition, a significant association was found between phase accuracy and the density and bundle diameter of the corpus callosum (CC), forming an interval-selective map where short and long intervals were behaviorally correlated with the anterior and posterior portions of the CC. These findings suggest that the structural properties of the SWM and DWM in the audiomotor system support the tapping synchronization abilities of subjects, as cortical U-fiber density is linked to the preferred tapping tempo and the bundle properties of the CC define an interval-selective topography.

Pomegranate juice recuperates N’-Nitrosodiethylamine-induced kidney injury: evidence from biochemical and histological approaches

BackgroundPomegranate is considered as one of the oldest elixirs having various properties. Renal fibrosis is a preliminary sign of pathological degradation in most ailments related to kidney. Several efforts have been made for the discovery of cost-effective and safe therapeutics for the alleviation of renal diseases. There is a major dearth of studies on the action of pomegranate juice (PGJ) against NDEA-instigated kidney injury. This study investigates the protective and antifibrotic action of PGJ in restricting the occurrence of experimental renal fibrosis in Wistar rats. Renal injury was generated by a single intraperitoneal dose of 10 ml kg−1 b.wt. (1% NDEA stock), while fresh PGJ (i.p.) in doses of 2 ml kg−1 b.wt was administered thrice a week on alternate days for two weeks to observe amelioration. The renal function indices (blood urea, creatinine, and uric acid), SOD, CAT, LPO levels and renal anatomy (H&E, MT, Picrosirius and SEM) were investigated.ResultsThe assessment of renal function demonstrates augmented levels of blood urea, creatinine and uric acid in NDEA-administered groups in comparison with controls. SOD, CAT declined significantly in NDEA Day-7- and Day-14-treated animals, while the MDA levels raised by ~ 70.5% and ~ 76.3% in these groups, respectively. However, supplementation of PGJ provided recuperation from these elevated levels in injured groups. H&E staining of the controls exhibited normal renal structure with intact glomerulus and Bowman’s capsule, while NDEA generated congestion of glomerular tuft, convoluted tubules with cloudy swelling and multiple subsidence of the renal tissue. Noticeable presence of collagen fibers in the interstitium of cortex region of kidney was observed by MT staining along with gross ultrastructural deterioration in NDEA-administered animals by electron microscopy. PGJ supplementation exhibited restoration of renal anatomy and physiology.ConclusionsPomegranate may be considered as a potent nutraceutical to prevent NDEA-induced renal damage and may be included as a daily dietary supplement.

Causal association among glaucoma, cerebral cortical structures, and Alzheimer's disease: insights from genetic correlation and Mendelian randomization.

Glaucoma and Alzheimer's disease are critical degenerative neuropathies with global impact. Previous studies have indicated that glaucomatous damage could extend beyond ocular structures, leading to brain alterations potentially associated with Alzheimer's disease risk. This study aimed to explore the causal associations among glaucoma, brain alterations, and Alzheimer's disease. We conducted a comprehensive investigation into the genetic correlation and causality between glaucoma, glaucoma endophenotypes, cerebral cortical surficial area and thickness, and Alzheimer's disease (including late-onset Alzheimer's disease, cognitive performance, and reaction time) using linkage disequilibrium score regression and Mendelian randomization. This study showed suggestive genetic correlations between glaucoma, cortical structures, and Alzheimer's disease. The genetically predicted all-caused glaucoma was nominally associated with a decreased risk of Alzheimer's disease (OR = 0.96, 95% CI: 0.93-0.99, P = 0.013). We found evidence for suggestive causality between glaucoma (endophenotypes) and 20 cortical regions and between 29 cortical regions and Alzheimer's disease (endophenotypes). Four cortical regions were causally associated with cognitive performance or reaction time at a significant threshold (P < 6.2E-04). Thirteen shared cortical regions between glaucoma (endophenotypes) and Alzheimer's disease (endophenotypes) were identified. Our findings complex causal relationships among glaucoma, cerebral cortical structures, and Alzheimer's disease. More studies are required to clarify the mediation effect of cortical alterations in the relationship between glaucoma and Alzheimer's disease.

Brain structure and activity predicting cognitive maturation in adolescence.

Cognitive abilities of primates, including humans, continue to improve through adolescence 1,2. While a range of changes in brain structure and connectivity have been documented 3,4, how they affect neuronal activity that ultimately determines performance of cognitive functions remains unknown. Here, we conducted a multilevel longitudinal study of monkey adolescent neurocognitive development. The developmental trajectory of neural activity in the prefrontal cortex accounted remarkably well for working memory improvements. While complex aspects of activity changed progressively during adolescence, such as the rotation of stimulus representation in multidimensional neuronal space, which has been implicated in cognitive flexibility, even simpler attributes, such as the baseline firing rate in the period preceding a stimulus appearance had predictive power over behavior. Unexpectedly, decreases in brain volume and thickness, which are widely thought to underlie cognitive changes in humans 5 did not predict well the trajectory of neural activity or cognitive performance changes. Whole brain cortical volume in particular, exhibited an increase and reached a local maximum in late adolescence, at a time of rapid behavioral improvement. Maturation of long-distance white matter tracts linking the frontal lobe with areas of the association cortex and subcortical regions best predicted changes in neuronal activity and behavior. Our results provide evidence that optimization of neural activity depending on widely distributed circuitry effects cognitive development in adolescence.

From Cats to the Cortex: Unravelling the Hierarchical Processing System of Vision and Brain Plasticity.

The groundbreaking research conducted by neurophysiologists David Hubel and Torsten Wiesel during the late 1950s and 1960s revolutionized the field of visual neuroscience. Through single-unit recordings in the visual cortex of cats, they made several key discoveries that fundamentally changed our understanding of visual processing. Their work introduced the concept of orientation selectivity, revealing that neurons in the visual cortex are specifically tuned to line orientations, thereby illustrating how the brain constructs visual representations through edge detection. Additionally, they discovered ocular dominance columns, the specialized cortical regions that respond preferentially to input from one eye, providing crucial insights into the organization of visual processing and the importance of binocular vision. Hubel and Wiesel's research also established the concept of a critical period in visual development, demonstrating that early visual experiences are essential for the proper maturation of the visual system. This discovery has had significant implications for understanding neural plasticity and the role of sensory input in neural development. The impact of their work goes beyond theoretical knowledge, contributing to the development of therapeutic strategies for some visual disorders and guiding current research into brain plasticity and visual processing. This review synthesizes the monumental contributions of Hubel and Wiesel, evaluating how their key discoveries have shaped subsequent research in visual neuroscience. It traces the evolution of knowledge related to visual pathways, feature detection, and brain plasticity, highlighting the enduring influence of their foundational work on contemporary studies. By exploring the progression from their pioneering findings to modern advancements, this review emphasizes the legacy of Hubel and Wiesel's contributions to our understanding of vision and neural function.

Disturbances of thalamus and prefrontal cortex contribute to cognitive aging: A structure-function coupling analysis based on KL divergence

Normal aging is accompanied by changes in brain structure and function associated with cognitive decline. Structural and functional abnormalities, particularly the prefrontal cortex (PFC) and subcortical regions, contributed to cognitive aging. However, it remains unclear how the synchronized changes in structure and function of individual brain regions affect the cognition in aging. Using 3D T1-weighted structural data and movie watching functional magnetic resonance imaging data in a sample of 422 healthy individuals (ages from 18 to 87 years), we constructed regional structure–function coupling (SFC) of cortical and subcortical regions by quantifying the distribution similarity of gray matter volume (GMV) and amplitude of low-frequency fluctuation (ALFF). Further, we investigated age-related changes in SFC and its relationship with cognition. With aging, increased SFC localized in PFC, thalamus and caudate nucleus, decreased SFC in temporal cortex, lateral occipital cortex and putamen. Moreover, the SFC in the PFC was associated with executive function and thalamus was associated with the fluid intelligence, and partially mediated age-related cognitive decline. Collectively, our results highlight that tighter structure–function synchron of the PFC and thalamus might contribute to age-related cognitive decline, and provide insight into the substrate of the thalamo-prefrontal pathway with cognitive aging.

Adaptive closed-loop modulation of cortical theta oscillations: Insights into the neural dynamics of navigational decision-making

Navigational decision-making tasks, such as spatial working memory (SWM), rely highly on information integration from several cortical and sub-cortical regions. Performance in SWM tasks is associated with theta rhythm, including low-frequency oscillations related to movement and memory. The interaction of the ventral hippocampus (vHPC) and medial prefrontal cortex (mPFC), reflected in theta synchrony, is essential in various steps of information processing during SWM. We used a closed-loop neurofeedback (CLNF) system to upregulate theta power in the mPFC and investigate its effects on circuit dynamics and behavior in animal models. Specifically, we hypothesized that enhancing the power of the theta rhythm in the mPFC might improve SWM performance. Animals were divided into three groups: closed-loop (CL), random-loop (RL), and OFF (without stimulation). We recorded local field potential (LFP) in the mPFC while electrical reward stimulation contingent on cortical theta activity was delivered to the lateral hypothalamus (LH), which is considered one of the central reward-associated regions. We also recorded LFP in the vHPC to evaluate the related subcortical neural changes. Results revealed a sustained increase in the theta power in both mPFC and vHPC for the CL group. Our analysis also revealed an increase in mPFC-vHPC synchronization in the theta range over the stimulation sessions in the CL group, as measured by coherence and cross-correlation in the theta frequency band. The reinforcement of this circuit improved spatial decision-making performance in the subsequent behavioral results. Our findings provide direct evidence of the relationship between specific theta upregulation and SWM performance and suggest that theta oscillations are integral to cognitive processes. Overall, this study highlights the potential of adaptive CLNF systems in investigating neural dynamics in various brain circuits.

Neural processing of sweet taste in reward regions is reduced following bariatric surgery.

Bariatric surgery reduces sweet-liking, but mechanisms remain unclear. We examined related brain responses. A total of 24 nondiabetic bariatric surgery and 21 control participants with normal weight to overweight were recruited for an observational controlled cohort study. They underwent sucrose taste testing outside the scanner followed by stimulation with 0.40M and 0.10M sucrose compared with water during functional magnetic resonance imaging. A total of 21 bariatric participants repeated these procedures after surgery. Perceived sweet intensity was not different among the control, presurgery, or postsurgery groups. Bariatric participants' preferred sweet concentration decreased after surgery (0.52M to 0.29M; p = 0.008). Brain reward system (ventral tegmental area, ventral striatum, and orbitofrontal cortex) region of interest analysis showed that 0.40M sucrose activation (but not 0.10M) decreased after surgery. Sensory region (primary somatosensory and primary taste cortex) 0.40M sucrose activation was unchanged by surgery and did not differ between control and bariatric participants. Primary taste cortex activation to 0.10M sucrose solution was greater in postsurgical bariatric participants compared with control participants. Bariatric surgery reduces the reward system response to sweet taste in women with obesity without affecting activity in sensory regions, which is consistent with reduced drive to consume sweet foods.

State-specific Regulation of Electrical Stimulation in the Intralaminar Thalamus of Macaque Monkeys: Network and Transcriptional Insights into Arousal.

Long-range thalamocortical communication is central to anesthesia-induced loss of consciousness and its reversal. However, isolating the specific neural networks connecting thalamic nuclei with various cortical regions for state-specific anesthesia regulation is challenging, with the biological underpinnings still largely unknown. Here, simultaneous electroencephalogram-fuctional magnetic resonance imaging(EEG-fMRI) and deep brain stimulation are applied to the intralaminar thalamus in macaques under finely-tuned propofol anesthesia. This approach led to the identification of an intralaminar-driven network responsible for rapid arousal during slow-wave oscillations. A network-based RNA-sequencing analysis is conducted of region-, layer-, and cell-specific gene expression data from independent transcriptomic atlases and identifies 2489 genes preferentially expressed within this arousal network, notably enriched in potassium channels and excitatory, parvalbumin-expressing neurons, and oligodendrocytes. Comparison with human RNA-sequencing data highlights conserved molecular and cellular architectures that enable the matching of homologous genes, protein interactions, and cell types across primates, providing novel insight into network-focused transcriptional signatures of arousal.

The Neural and Computational Architecture of Feedback Dynamics in Mouse Cortex during Stimulus Report.

Conscious reportability of visual input is associated with a bimodal neural response in the primary visual cortex (V1): an early-latency response coupled to stimulus features and a late-latency response coupled to stimulus report or detection. This late wave of activity, central to major theories of consciousness, is thought to be driven by the prefrontal cortex (PFC), responsible for "igniting" it. Here we analyzed two electrophysiological studies in mice performing different stimulus detection tasks and characterized neural activity profiles in three key cortical regions: V1, posterior parietal cortex (PPC), and PFC. We then developed a minimal network model, constrained by known connectivity between these regions, reproducing the spatiotemporal propagation of visual- and report-related activity. Remarkably, while PFC was indeed necessary to generate report-related activity in V1, this occurred only through the mediation of PPC. PPC, and not PFC, had the final veto in enabling the report-related late wave of V1 activity.

Cerebral Synchronization Between Mothers and Their Newborns During Breastfeeding.

Introduction: Breastfeeding is a fundamental biological function in mammals, allowing the progeny to develop in a physiological way. A physical and emotional dialog between mothers and offspring during breastfeeding has been described as part of the attachment relationship, and a synchronicity between maternal and neonatal brains can be hypothesized. This study aimed to assess if neonatal and maternal cortical areas activated during breastfeeding are functionally synchronized since the second day of life. Materials and Methods: Twenty mothers and their term newborns were enrolled. Cortical activation during breastfeeding was identified by multichannel near-infrared spectroscopy, which detects changes in haemoglobin concentration from multiple cortical regions. Functional activity was simultaneously detected (hyperscanning) in mothers and newborns' frontal and motor/primary somatosensory cortical areas during the first 5 minutes of breastfeeding. Cluster analysis and Student's t test were used to detect oxygenated haemoglobin increase, as cortical activation estimate. Wavelet transform coherence (WTC) analysis was used to identify a possible synchronization between maternal and neonatal activated cortical regions. Results: Mothers showed an activation of the central motor/primary somatosensory cortex, above the sagittal fissure. In newborns, the bilateral frontal cortex was activated. WTC analysis revealed two different cyclical synchronizations between mothers and infants' activated cortical regions. Conclusions: Such evidence may reflect a very early common sharing of experiences, possibly associated with reciprocal dynamic motor adjustments, hormonal coregulation, and somatic stimulations and sensations. The observed cyclical neural synchronization, between the mother and her newborn's cortex during breastfeeding, may play an important role in promoting their bonding.

Kappa opioid receptor availability predicts severity of anhedonia in schizophrenia.

The kappa opioid receptor (KOR) and its endogenous agonist dynorphin have been implicated in multiple psychiatric conditions including psychotic disorders. We tested the hypotheses that kappa expression is elevated and associated with psychotic symptoms in schizophrenia. We measured kappa expression in unmedicated patients with schizophrenia (7 female, 6 male) and matched controls (7 female, 6 male) with positron emission tomography (PET). We also acquired a measurement of cumulative dopamine activity over the life span in the same subjects using neuromelanin sensitive MRI. We hypothesized that neuromelanin accumulation would be higher in patients than controls and that in patients there would be a positive association between KOR availability and neuromelanin accumulation. Fourteen patients and thirteen controls were enrolled. Whole brain dynamic PET imaging data using the KOR selective tracer [18F]LY245998 were acquired. Distribution volume (VT) was measured with region of interest analysis in 14 brain regions. Neuromelanin accumulation in midbrain dopaminergic nuclei was assessed in the same subjects. Positive and negative symptoms were measured by a clinical psychologist. We did not observe group level differences in KOR expression, neuromelanin accumulation or relationships of these to positive symptoms. Unexpectedly, we did observe strong positive associations between KOR expression and symptoms of anhedonia in the patients (Pearson r > 0.7, uncorrected p < 0.01 in 8 cortical brain regions). We also observed moderate associations between KOR expression and neuromelanin levels in patients. In conclusion, we did not observe a relationship between kappa and symptoms of psychosis but the observed relationship to the negative symptom of anhedonia is in line with recent work testing kappa antagonism as a therapy for anhedonia in depression.

The uniqueness of human vulnerability to brain aging in great ape evolution.

Aging is associated with progressive gray matter loss in the brain. This spatially specific, morphological change over the life span in humans is also found in chimpanzees, and the comparison between these great ape species provides a unique evolutionary perspective on human brain aging. Here, we present a data-driven, comparative framework to explore the relationship between gray matter atrophy with age and recent cerebral expansion in the phylogeny of chimpanzees and humans. In humans, we show a positive relationship between cerebral aging and cortical expansion, whereas no such relationship was found in chimpanzees. This human-specific association between strong aging effects and large relative cortical expansion is particularly present in higher-order cognitive regions of the ventral prefrontal cortex and supports the "last-in-first-out" hypothesis for brain maturation in recent evolutionary development of human faculties.

Longitudinal mapping of cortical change during early adolescence associated with prenatal tobacco and/or alcohol exposure in the Adolescent Brain Cognitive Development Study.

The effects of prenatal alcohol (PAE) and tobacco exposure (PTE) on adolescent neuroanatomical development are typically evaluated cross-sectionally. It is unclear if observed effects persist throughout life or reflect different developmental trajectories. To determine how PAE and PTE are associated with cortical structure and development across two timepoints in early adolescence. Observational, longitudinal analyses of data within the Adolescent Brain Cognitive Development Study. 21 study sites in the United States. 5,417 youth participants, aged ~9-12 years old. PAE and PTE based on caregiver (self) reports of alcohol/tobacco use during pregnancy, before and after pregnancy recognition. Cortical thickness (mm) and cortical surface area (mm2) measured approximately 2 years apart in early adolescence, across 68 bilateral cortical regions. At baseline data collection, youth participants were ~9.9 years old (SD=0.6). At the second neuroimaging appointment, youth participants were ~11.9 years old (SD=0.6). When modelling cortical thickness, we controlled for individuals' whole-brain volume; when modelling cortical surface area, individuals' total surface area. Cortical thickness generally declined with age. Cortical surface area either expanded or contracted with age, depending on region. PAE had minimal effects on cortical structure (main effects) and development (PAE×Age interactions). PTE had robust effects on cortical thickness and was associated with faster rates of cortical thinning in several regions within the frontal lobe. Post hoc analyses on (1) the effects of PTE for those who continued tobacco use after pregnancy recognition and (2) the effects of PTE in those who did not also use alcohol revealed weaker effects. PTE had robust effects on neuroanatomical structure and longitudinal development, particularly cortical thickness. Analyzing developmental cortical trajectories informs how PTE and/or PAE not only affects cortical structure but how it develops long after those prenatal exposures occurred. Future analyses involving cotinine biomarkers of PTE would enhance the temporal resolution of the ABCD Study®'s PTE-related queries of tobacco use before and after learning of the pregnancy.

An Integrated Hybrid Convolutional-Support Vector Machine (CSVM) Model with the CWT Method for Hearing Disorder Detection using AEP Signals

Hearing disorder is the most widespread sensory disability worldwide, impairing human communication and learning. An early and accurate hearing disorder detection system using an electroencephalogram (EEG) is the appropriate technique for dealing with this concern. The most significant modality for diagnosing hearing deficiency among EEG control signals is the auditory evoked potential (AEP), which is generated in the cortical region of the brain through auditory stimulus. This study aims to develop an efficient approach for detecting hearing disorders. For this purpose, this study has designed a hybrid model based on the convolutional operation of CNN and the SVM classifier. Initially, the CWT method was utilized to transform the raw AEP signals into time-frequency images. Then, the extracted features were classified using the proposed CSVM model. To test the robustness of the proposed model, this study also implemented a convolutional neural network (CNN) and support vector machine (SVM) with the same parameters. The experimental results with the hybrid CSVM model showed superior performance on the publicly available AEP dataset by achieving 94.48% testing accuracy, 96.40% precision, 92.96% recall, 94.65% F1 score, 88.95% Cohen Kappa score, which indicates that the proposed hybrid model could be used for early hearing disorder detection. Future enhancements will concentrate on identifying different hearing-signal-based data and the cloud-based, automated classification of AEP signals.

The "limbic network," comprising orbitofrontal and anterior temporal cortex, is part of an extended default network: Evidence from multi-echo fMRI.

Resting-state functional magnetic resonance imaging (fMRI) investigations have provided a view of the default network (DN) as composed of a specific set of frontal, parietal, and temporal cortical regions. This spatial topography is typically defined with reference to an influential network parcellation scheme that designated the DN as one of seven large-scale networks (Yeo et al., 2011). However, the precise functional organization of the DN is still under debate, with studies arguing for varying subnetwork configurations and the inclusion of subcortical regions. In this vein, the so-called limbic network-defined as a distinct large-scale network comprising the bilateral temporal poles, ventral anterior temporal lobes, and orbitofrontal cortex-is of particular interest. A large multi-modal and multi-species literature on the anatomical, functional, and cognitive properties of these regions suggests a close relationship to the DN. Notably, these regions have poor signal quality with conventional fMRI acquisition, likely obscuring their network affiliation in most studies. Here, we leverage a multi-echo fMRI dataset with high temporal signal-to-noise and whole-brain coverage, including orbitofrontal and anterior temporal regions, to examine the large-scale network resting-state functional connectivity of these regions and assess their associations with the DN. Consistent with our hypotheses, our results support the inclusion of the majority of the orbitofrontal and anterior temporal cortex as part of the DN and reveal significant heterogeneity in their functional connectivity. We observed that left-lateralized regions within the temporal poles and ventral anterior temporal lobes, as well as medial orbitofrontal regions, exhibited the greatest resting-state functional connectivity with the DN, with heterogeneity across DN subnetworks. Overall, our findings suggest that, rather than being a functionally distinct network, the orbitofrontal and anterior temporal regions comprise part of a larger, extended default network.

Neuritin Controls Axonal Branching in Serotonin Neurons: A Possible Mediator Involved in the Regulation of Depressive and Anxiety Behaviors via FGF Signaling.

Abnormal neuronal morphological features, such as dendrite branching, axonal branching, and spine density, are thought to contribute to the symptoms of depression and anxiety. However, the role and molecular mechanisms of aberrant neuronal morphology in the regulation of mood disorders remain poorly characterized. Here, we show that neuritin, an activity-dependent protein, regulates the axonal morphology of serotonin neurons. Male neuritin knock-out (KO) mice harbored impaired axonal branches of serotonin neurons in the medial prefrontal cortex and basolateral region of the amygdala (BLA), and male neuritin KO mice exhibited depressive and anxiety-like behaviors. We also observed that the expression of neuritin was decreased by unpredictable chronic stress in the male mouse brain and that decreased expression of neuritin was associated with reduced axonal branching of serotonin neurons in the brain and with depressive and anxiety behaviors in mice. Furthermore, the stress-mediated impairments in axonal branching and depressive behaviors were reversed by the overexpression of neuritin in the BLA. The ability of neuritin to increase axonal branching in serotonin neurons involves fibroblast growth factor (FGF) signaling, and neuritin contributes to FGF-2-mediated axonal branching regulation in vitro. Finally, the oral administration of an FGF inhibitor reduced the axonal branching of serotonin neurons in the brain and caused depressive and anxiety behaviors in male mice. Our results support the involvement of neuritin in models of stress-induced depression and suggest that neuronal morphological plasticity may play a role in controlling animal behavior.

Pathologic Substrates of Structural Brain Network Resilience and Topology in Parkinson Disease Decedents.

In Parkinson disease (PD), α-synuclein spreading through connected brain regions leads to neuronal loss and brain network disruptions. With diffusion-weighted imaging (DWI), it is possible to capture conventional measures of brain network organization and more advanced measures of brain network resilience. We aimed to investigate which neuropathologic processes contribute to regional network topologic changes and brain network resilience in PD. Using a combined postmortem MRI and histopathology approach, PD and control brain donors with available postmortem in situ 3D T1-weighted MRI, DWI, and brain tissue were selected from the Netherlands Brain Bank and Normal Aging Brain Collection Amsterdam. Probabilistic tractography was performed, and conventional network topologic measures of regional eigenvector centrality and clustering coefficient, and brain network resilience (change in global efficiency upon regional node failure) were calculated. PSer129 α-synuclein, phosphorylated-tau, β-amyloid, neurofilament light-chain immunoreactivity, and synaptophysin density were quantified in 8 cortical regions. Group differences and correlations were assessed with rank-based nonparametric tests, with age, sex, and postmortem delay as covariates. Nineteen clinically defined and pathology-confirmed PD (7 F/12 M, 81 ± 7 years) and 15 control (8 F/7 M, 73 ± 9 years) donors were included. With regional conventional measures, we found lower eigenvector centrality only in the parahippocampal gyrus in PD (d = -1.08, 95% CI 0.003-0.010, p = 0.021), which did not associate with underlying pathology. No differences were found in regional clustering coefficient. With the more advanced measure of brain network resilience, we found that the PD brain network was less resilient to node failure of the dorsal anterior insula compared with the control brain network (d = -1.00, 95% CI 0.0012-0.0015, p = 0.018). This change was not directly driven by neuropathologic processes within the dorsal anterior insula or in connected regions but was associated with higher Braak α-synuclein staging (rs = -0.40, p = 0.036). Although our cohort might suffer from selection bias, our results highlight that regional network disturbances are more complex to interpret than previously believed. Regional neuropathologic processes did not drive regional topologic changes, but a global increase in α-synuclein pathology had a widespread effect on brain network reorganization in PD.

The Role of Mycorrhizal Fungi in Orchids Mycobiont and Orchids.

In nature, orchid plants are obligate myco-heterotrophs, and rely on mycorrhizal nutrient resources to grow and sustain in the wild, until they become physiologically active photosynthetic plants. Their seeds lack nutrient reserves and receive the necessary carbon from symbiotic fungi during germination. A mycorrhizal fungus provides nutrients, especially sugars, as well as water to the corresponding host plant. The range and distribution of orchid mycorrhizal fungi influence the survivability of orchid populations in their natural habitats. Mycorrhizae form symbiotic connections with the parenchymatous tissues of the roots of orchid plants. The objective of this study was to examine the presence of mycorrhiza in the roots of Aerides multiflora during the vegetative phase Methods: Fresh roots were hand-sectioned, and thin sections were observed under the microscope to locate the presence of mycorrhiza. Simultaneously, to observe the expansion of mycorrhiza in the cortical region. During the vegetative phase of plant growth, a peloton-like structure forms within the cortical region of the orchid roots. Mycorrhizae was observed to be distributed throughout the cortical layer of the root. This communication reviews the role of mycorrhiza in orchid plants.