Biology subjects

Pereira, E.

Publications and source records attributed to Pereira, E..

17 recordsLinked to original sources

bioRxiv2026

SeCAT (Sequence Consensus Amplicon Trimming): a simulation-informed Nextflow pipeline for cross-study harmonisation of 16S rRNA metabarcoding datasets

Global syntheses of 16S rRNA metabarcoding data rely on combining datasets, yet amplicon sequence variants generated with different primer pairs can rarely be compared directly. Existing approaches correct batch effects statistically or aggregate taxonomically; none first establishes whether the sequences are positionally comparable. We present SeCAT (Sequence Consensus Amplicon Trimming), a Nextflow pipeline that maps every studys variants onto a 16S rRNA full-length reference alignment, determines the largest window shared across studies, and tests by simulation whether trimming to that window degrades community structure before any data are merged. Applied to thirteen marine studies sequenced with three primer sets, twelve converged on a consensus window with a median trimmed read length of 249 bp (9,582 alignment columns). Degradation tests across twelve studies and six taxonomic ranks (72 study-rank combinations) returned 31 passes, 38 cautions and three confirmed failures. Eleven studies (682 samples after filtering) were harmonised (trimmed to the window and merged), collapsing 20,891 primer-specific variants into 12,667 MetaASVs, trimmed sequences deduplicated across studies. Harmonisation preserved community structure at family level (Mantel r = 1.00; Procrustes m{superscript 2} < 0.001) without adding between-study variance (|{Delta}R{superscript 2}| < 0.001). Alpha diversity, including observed richness, was recovered across all levels (intraclass correlations 0.93-1.00), whereas sequence-level congruence was moderate (Procrustes m{superscript 2} = 0.52), as expected where between-study similarity at sequence level exists only after harmonisation. The harmonised output supports synthesis from aggregated ranks down to exact sequences. By establishing positional comparability before merging, SeCAT opens the archive of primer-fragmented 16S rRNA surveys to sequence-level synthesis.

bioinformatics↗

bioRxiv2026

Argentina Explores Its Bathyal and Abyssal Zone for the First Time Using an ROV: New Biodiversity Discoveries and Unprecedented Public Engagement

Between July 23 and August 12, 2025, members of the scientific group Grupo de Estudios del Mar Profundo de Argentina (GEMPA) and collaborators conducted the Talud Continental IV expedition in the Mar del Plata Canyon. The expedition was conducted aboard the R/V Falkor (too) in partnership with Schmidt Ocean Institute (SOI), marking the first deployment of a Remotely Operated Vehicle (ROV) in Argentinean bathyal and abyssal waters. The Mar del Plata Canyon was explored in 2012 and 2013 by CONICET researchers using bottom trawls aboard the R/V Puerto Deseado (CONICET, Argentina). This new expedition combined high-definition video surveys, acoustic seafloor mapping, and physicochemical water-column characterization, with in situ sensing and sampling of fauna (animal specimens, zooplankton, and environmental DNA), water, sediments, and rock to characterize biodiversity and habitats between 880 and 3900 m. The expedition revealed extensive Bathelia cold-water coral reefs, soft-coral gardens, and more than 40 species suspected to be new to science, six of which have already been formally described. Anthropogenic debris, including plastics and fishing gear, was recorded at multiple stations, reaching even the deepest sites, underscoring the extent of human influence on these environments. The Talud Continental IV expedition was successful both scientifically and in promoting deep-ocean literacy and engagement, with broad outreach conducted through SOIs outreach and community engagement programs. The Ship-to-Shore program connected scientists on board with students and educators through live interactive sessions, engaging over 900 students from 19 institutions across Argentina and the United States. The live ROV divestreams, broadcast through SOIs YouTube and Twitch platforms, reached record levels of public engagement, with [~]19 million total views by July 23rd. The national and international press responded with extensive coverage and interview requests, resulting in over 3,900 international stories. Scientists continued to engage with the public after the expedition through talks at schools and public institutions. The expeditions achievements promise to usher in a new era of scientific discovery in the Southwestern Atlantic and underscore the value of integrating exploration, conservation, and outreach to inspire wonder and curiosity about the deep-sea in society. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/726651v3_ufig1.gif" ALT="Figure 1"> View larger version (138K): org.highwire.dtl.DTLVardef@1457548org.highwire.dtl.DTLVardef@116f19aorg.highwire.dtl.DTLVardef@14fbb26org.highwire.dtl.DTLVardef@187c3a4_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2026

Direct effector recognition by a tandem kinase triggers non-canonical immunity in wheat

Tandem kinase proteins (TKPs) are an important class of disease resistance genes in cereal crops alongside nucleotide-binding (NB-ARC) leucine-rich repeat (LRR) (NLR) receptors. Here, we cloned the wheat (Triticum aestivum) resistance gene Lr41, which encodes a TKP with a C-terminal fusion, and its paired effector gene AvrLr41 from the rust pathogen Puccinia triticina. AvrLr41 is unusually large and highly divergent from most fungal effectors and is directly recognized by Lr41 through its pseudokinase domain. Immune activation mediated by Lr41 require auxiliary helper proteins, including either a minimal coiled-coil (CC) helper protein or its full-length NLR ortholog. These findings reveal a non-canonical immune system in which a kinase-type receptor directly recognizes an effector and recruits either CC or NLR helpers, demonstrating that full-length NLRs are not strictly required for NLR-linked immune execution and expanding the functional repertoire of disease resistance proteins in crops.

plant biology↗

bioRxiv2025

Post-Inhibitory Rebound by δ-Cells Transforms Inhibition into Excitationand Redefines Islet Plasticity.

The coordination of hormone secretion within the pancreatic islet remains incompletely understood. Here we identify post-inhibitory rebound (PIR), a transient excitatory overshoot of glucoregulatory hormones following inhibitory signaling, as a fundamental and previously unrecognized feature of islet physiology. Human islets from donors with type 2 diabetes displayed concomitantly elevated insulin and somatostatin secretion with tightly correlated dynamics, a pattern reproduced in islets from high-fat-diet-fed mice. Using a combination of cell-type-specific chemogenetic and optogenetic approaches, high-resolution triple-hormone perifusion, Ca{superscript 2} imaging, in vivo islet grafts, and physiological ligands, we demonstrate that transient {delta}-cell activation or inhibition consistently triggers rebound excitation of {beta}- and -cells. These responses generate glucose-dependent, synchronized oscillations of insulin and glucagon secretion that are partially mediated by somatostatin receptor signaling. Mechanistic insights obtained in mouse islets were recapitulated using translatable approaches in human islets, establishing the relevance of this dynamic signaling framework across species. In vivo, selective {delta}-cell modulation bidirectionally regulated systemic glucose tolerance, confirming {delta}-cell control over endocrine output. These findings support a model in which somatostatin signaling encodes hormone output through temporal dynamics rather than tonic inhibition. By reframing somatostatin as a dynamic regulator of excitability, we identify {delta}-cell-driven rebound as a mechanism that converts inhibition into coordinated endocrine output. Together, this work establishes a revised framework for intra-islet paracrine crosstalk in which temporal dynamics, rather than static inhibition, govern endocrine coordination. Significance StatementHormone secretion in the pancreatic islet has long been explained by inhibitory feedback loops, with somatostatin viewed as a static suppressor of insulin and glucagon release. Our study overturns this paradigm by identifying post-inhibitory rebound (PIR) as a dynamic property of intra-islet signaling. {delta}-cell-driven PIR synchronizes - and {beta}-cell activity, enabling adaptive, glucose-dependent hormone release and revealing that somatostatin confers system plasticity when needed. This work establishes a revised model of intra-islet paracrine crosstalk in which {delta}-cell-driven rebound dynamics, rather than static inhibition, determine endocrine coordination and system plasticity. Our discovery reframes inhibition as a rhythmic and regenerative force, positioning PIR as a potentially generalizable mechanism of excitability across biological systems. HighlightsO_LI{delta}-cells convert inhibition into excitation. Transient somatostatin signals trigger post-inhibitory rebound (PIR) in {beta}- and -cells, generating glucose-dependent synchronized hormone oscillations. C_LIO_LIProvides a mechanistic explanation for a long-standing paradox in human type 2 diabetes. Elevated basal insulin and somatostatin secretion are positively correlated; PIR explains this co-hypersecretion. C_LIO_LIAsymmetric {delta}-cell control confers islet plasticity. Stronger inhibition of -cells versus {beta}-cells enables balanced insulin/glucagon output during feeding or glucagon-skewed surges for hypoglycemia protection. C_LIO_LIMulti-scale validation across species. Chemogenetics, optogenetics, native ligands, Ca{superscript 2} imaging, in vivo grafts, and a data-informed phenomenological model demonstrate conservation from mouse to human islets. C_LIO_LIInhibition is instructive. A revised model of intra-islet paracrine crosstalk in which cell-type-specific temporal dynamics encode hormone output through rebound. C_LI Graphical AbstractSomatostatin, long considered a static inhibitor of growth and secretion, instead acts as a dynamic modulator that transforms inhibition into robust, context-dependent excitation. In the islet, amplified SST pulses drive rebound excitation to promote balanced insulin and glucagon output during anabolic demand, while dampening produces glucagon-skewed surges for protection against hypoglycemia. Inhibition in the islet is not merely suppressive but instructive, encoding future hormone output through rebound dynamics. The same pulse-rebound principle may operate in SST-rich systems such as the brain, gut, and tumors, where dynamic modulation of SST signaling confers adaptability and robustness rather than tonic suppression. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/687745v2_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1a88336org.highwire.dtl.DTLVardef@3e618aorg.highwire.dtl.DTLVardef@175d94forg.highwire.dtl.DTLVardef@decf4_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2025

Seasonal dynamics and thermal vulnerability of marine microbial communities in Uruguayan coastal waters

In an era of accelerating ocean warming, understanding the drivers of microbial community composition is more urgent than ever. Long-term time-series studies are particularly powerful for this purpose. However, most previous work remains confined to the Northern Hemisphere and focuses solely on taxonomy, leaving the Southern Hemisphere underrepresented and microorganisms functional dimensions underexplored. Moreover, phenomena such as current-driven community shifts and microbial vulnerability to warming remain poorly understood. Here, we address these gaps by analyzing microbial communities over two years at the South Atlantic Microbial Observatory (SAMO), located off the coast of Uruguay within a Marine Protected Area. SAMO, situated under the contrasting influences of the Brazil and Malvinas currents and recognized as a global-warming hotspot, provides an ideal setting to study the temporal dynamics of marine microbial communities. Using shotgun metagenomics and 16S rRNA amplicon sequencing, we revealed strong seasonal shifts driven by environmental variability and the influence of these two ocean currents, resulting in two community states (summer-autumn vs winter-spring). These states exhibited contrasting composition, diversity, and assembly mechanisms. Further, our results show that taxonomic and functional diversity trends diverge between these periods. Crucially, our work suggests that the predicted tropicalization of Uruguays coast is likely to boost taxonomic richness but erode functional repertoires, while also increasing vulnerability to ocean warming, potentially undermining biogeochemical functioning.

microbiology↗

bioRxiv2025

Microvascular homeostasis is compromised in pancreatic islets in a mouse model of beta cell loss and low-grade inflammation

Vascular dysfunction is considered a consequence of diabetes. However, in pancreatic islets, some haemodynamic changes occur before the onset of symptoms. The underlying mechanisms driving islet vascular abnormalities have not been fully characterized, but islet pericyte dysfunction appears to be an early event in the pathogenesis of human type 1 diabetes (T1D). It remains to be investigated, however, how abnormal pericyte physiology affects their ability to regulate islet blood flow and vascular permeability. To address this issue, we treated mice with multiple subdiabetogenic doses of the beta cell toxin streptozotocin (STZ; 50mg/kg) and recorded islet vascular responses when animals developed glucose intolerance but were still not diabetic (average fed glycemia <200 mg/dL). At this stage, accompanying increased macrophage density, islet pericytes adopted a myofibroblast-like appearance and interacted closely with endothelial cells expressing high levels of the adhesion molecule ICAM-1. This phenotypical switch of pericytes in STZ-treated mice had functional repercussions: it impacted glucose-induced vasomotor responses ex vivo in living pancreas slices and hyperglycemia-stimulated increases in islet blood flow recorded in vivo in the exteriorized pancreas. Impaired vasomotor responses were accompanied by enhanced extravazation of a fluorescent dextran (500 kDa) from vessels and accumulation in the interstitial space surrounding islets in STZ-treated mice. Our study indicates that abnormal pericyte function, and compromised capacity to regulate blood flow and vascular integrity, are part of a pathogenic process occurring in islets before diabetes onset, associated with a loss of functional beta cell mass and inflammation. Article highlightsO_LIFunctional and morphological alterations of islet capillaries occur in mice early after multiple low dose STZ treatment; C_LIO_LIIslet pericytes remodel and express higher levels of the myofibroblast marker periostin upon STZ treatment; C_LIO_LIIslet pericyte cytosolic Ca2+ and vasomotor responses to high glucose are impaired in living pancreas slices from mice treated with STZ; C_LIO_LIIslet hyperemic responses to increases in glycemia recorded in the exteriorized pancreas are abolished in STZ-treated mice; C_LIO_LIVascular alterations are associated with a pro-inflammatory environment as islets from STZ-treated mice have more macrophages, an inflamed and leaky endothelium. C_LI

physiology↗

bioRxiv2025

Beyond beta: Aperiodic broadband power reflects Parkinson's disease severity - a multicenter study

Parkinsons disease is linked to increased beta oscillations in the subthalamic nucleus, which correlate with motor symptoms. However, findings across studies have varied. Our standardized analysis of multicenter datasets shows that small sample sizes contributed to these discrepancies--a challenge we address by pooling datasets into one large cohort (n=119). Moving beyond beta power, we disentangled spectral components reflecting distinct neural processes. Combining aperiodic offset, low beta, and low gamma oscillations explained significantly more variance in symptom severity than beta alone. Moreover, interhemispheric within-patient analyses showed that, unlike beta oscillations, aperiodic broadband power-likely reflecting spiking activity-was increased in the more affected hemisphere. These findings identify aperiodic broadband power as a potential biomarker for adaptive deep brain stimulation and provide novel insights into the relationship between subthalamic hyperactivity and motor symptoms in human Parkinsons disease.

neuroscience↗

bioRxiv2024

Evoked resonant neural activity outperforms spectral markers in decoding sleep from the subthalamic nucleus

BackgroundDeep brain stimulation is a treatment for advanced Parkinsons disease and currently tuned to target motor symptoms during daytime. Parkinsons disease is associated with multiple nocturnal symptoms such as akinesia, insomnia and sleep fragmentation which may require adjustments of stimulation during sleep for best treatment outcome. ObjectivesThere is a need for a robust biomarker to guide stimulation titration across sleep stages. This study aimed to investigate whether evoked resonant neural activity (ERNA) is modulated during sleep. MethodsWe recorded local field potentials from the subthalamic nucleus of four Parkinsons patients with externalised electrodes while applying single stimulation pulses to investigate the effect of sleep on ERNA. ResultsWe found that ERNA features change with wakefulness and sleep stages, and are correlated with canonical frequency bands and heart rate. We further evaluated the performance of machine learning models in classifying non-REM sleep versus wakefulness and found that ERNA amplitude outperforms all spectral markers. ConclusionsGiven the heterogeneity of spectral features during sleep, their susceptibility to movement artefacts and superior classification accuracy of models using ERNA features, this study paves the way for ERNA as a marker for automatic stimulation titration during sleep and improved patient care.

neuroscience↗

bioRxiv2022

Breast cancer progression and metastasis to lymph nodes reveals cancer cell plasticity and MHC class II-mediated immune regulation

Tumor-draining lymph nodes are critical sites for generating tumor antigen-specific T cells and are associated with durable immune responses. However, lymph nodes are often the first site of metastasis and lymph node metastases portend worse outcomes. Through cross-species single cell gene expression analysis of breast cancer progression and metastasis to lymph nodes, we uncovered features that define the heterogeneity, plasticity, and immune evasion of cancer cells. Notably, a subpopulation of metastatic cancer cells in the lymph node were marked by high levels of MHC class II (MHC-II) gene expression both in mice and humans. Mechanistically, the IFN-{gamma} and JAK/STAT signaling pathways mediate MHC-II expression in cancer cells. Ablation of IFNGR1/2 or CIITA, the transactivator of MHC-II, in cancer cells prevented tumor progression. Interestingly, MHC-II+ cancer cells lacked co-stimulatory molecule expression, engendered the expansion of regulatory T cells and blunted CD4+ effector T cells in the tumor-draining lymph nodes and favor tumor progression. Overall, our data suggests that cancer cell plasticity during breast cancer progression and metastasis to lymph nodes endows metastatic cells with the ability to avoid immune surveillance. These data provide the basis for new opportunities to therapeutically stimulate anti-cancer immune responses against local and systemic metastases.

cancer biology↗

bioRxiv2022

The aperiodic exponent of subthalamic field potentials reflects excitation/inhibition balance in Parkinsonism: a cross-species study in vivo

AO_SCPLOWBSTRACTC_SCPLOWPeriodic features of neural time series data, such as local field potentials (LFP), are often quantified using power spectra. While the aperiodic exponent of spectra is typically disregarded, it is nevertheless modulated in a physiologically-relevant manner and was recently hypothesised to reflect excitation/inhibition (E/I) balance in neuronal populations. Here, we used a cross-species in vivo electrophysiological approach to test the E/I hypothesis in the context of experimental and idiopathic Parkinsonism. We demonstrate in dopamine-depleted rats that aperiodic exponents and power at 30-100 Hz in subthalamic nucleus (STN) LFPs reflect defined changes in basal ganglia network activity; higher aperiodic exponents tally with lower levels of STN neuron firing and a balance tipped towards inhibition. Using STN-LFPs recorded from awake Parkinsons patients, we show that higher exponents accompany dopaminergic medication and deep brain stimulation (DBS) of STN, consistent with untreated Parkinsons manifesting as reduced inhibition and hyperactivity of STN. These results suggest that the aperiodic exponent of STN-LFPs in Parkinsonism reflects E/I balance, and might be a candidate biomarker for adaptive DBS.

neuroscience↗

bioRxiv2022

First Record of Aedes (Stegomyia) albopictus (Diptera: Culicidae) in the state of Acre, Brazil

IntroductionAedes (Stegomyia) albopictus (Skuse, 1854) was reported in Brazil for the first time in 1986, and has displayed successful expansion throughout the Brazilian territory. MethodsDuring a routine activity to control dengue conducted by the Division of Entomology of the Municipal Health Department in Rio Branco, adults and immatures of Culicidae were collected in a peri-urban area. ResultsThe Culicidae forms identified indicated that they belonged to the species Ae. albopictus. ConclusionsThis is the first official record of the presence of Ae. albopictus in the state of Acre, confirming its current presence in all Brazilian states.

zoology↗

bioRxiv2021

Pericyte control of pancreatic islet blood flow impacts glucose homeostasis

The pancreatic islet depends on blood supply to efficiently sense plasma glucose levels and deliver insulin and glucagon into the circulation. Long thought to be passive conduits of nutrients and hormones, islet capillaries were recently found to be densely covered with contractile pericytes, suggesting local control of blood flow. Here we determined the contribution of islet pericytes to the regulation of islet blood flow, plasma insulin and glucagon levels, and glycemia. Selective optogenetic activation of pericytes in intraocular islet grafts contracted capillaries and diminished blood flow. In awake mice, acute clamping of islet blood flow by optogenetic or pharmacological activation of pericytes disrupted hormonal responses, glycemia, and glucose tolerance. Our findings indicate that pericytes mediate vascular responses in the islet that are required for adequate hormone secretion and glucose homeostasis. Vascular deficiencies commonly seen in the islets of people with type 2 diabetes may impair regulation of islet blood flow and thus precipitate islet dysfunction.

physiology↗

bioRxiv2021

Mining metagenomes for natural product biosynthetic gene clusters: unlocking new potential with ultrafast techniques

Microorganisms produce an immense variety of natural products through the expression of Biosynthetic Gene Clusters (BGCs): physically clustered genes that encode the enzymes of a specialized metabolic pathway. These natural products cover a wide range of chemical classes (e.g., aminoglycosides, lantibiotics, nonribosomal peptides, oligosaccharides, polyketides, terpenes) that are highly valuable for industrial and medical applications1. Metagenomics, as a culture-independent approach, has greatly enhanced our ability to survey the functional potential of microorganisms and is growing in popularity for the mining of BGCs. However, to effectively exploit metagenomic data to this end, it will be crucial to more efficiently identify these genomic elements in highly complex and ever-increasing volumes of data2. Here, we address this challenge by developing the ultrafast Biosynthetic Gene cluster MEtagenomic eXploration toolbox (BiG-MEx). BiG-MEx rapidly identifies a broad range of BGC protein domains, assess their diversity and novelty, and predicts the abundance profile of natural product BGC classes in metagenomic data. We show the advantages of BiG-MEx compared to standard BGC-mining approaches, and use it to explore the BGC domain and class composition of samples in the TARA Oceans3 and Human Microbiome Project datasets4. In these analyses, we demonstrate BiG-MExs applicability to study the distribution, diversity, and ecological roles of BGCs in metagenomic data, and guide the exploration of natural products with clinical applications.

bioinformatics↗

bioRxiv2020

Age and axon-specific forms of cortical remyelination by divergent populations of NG2-glia

Myelin is critical for neural circuit function and its destruction is widespread in neurodegenerative disease and aging. In these conditions, homeostatic repair mechanisms initiate oligodendrocyte replacement by resident progenitor cells called NG2-glia. To investigate the cellular dynamics of this repair we developed a novel demyelination model by combining intravital myelin imaging with a targeted single-cell ablation technique called 2Phatal. Oligodendrocyte 2Phatal activated a stereotyped degeneration cascade which triggered remyelination by local NG2-glia. Remyelination efficiency was dependent on initial myelin patterning and dynamic imaging revealed rapid repair mechanisms resulting in near-seamless transitions between myelin loss and repair. A subset of morphologically complex NG2-glia executed this remyelination, pointing towards unrecognized functional diversity within this population. Age-related demyelination mirrored the degenerative cascade observed with 2Phatal, while remyelination in aging was defective due to failed oligodendrogenesis. Thus, oligodendrocyte 2Phatal revealed cellular diversity within the oligodendrocyte lineage and uncovered novel forms of rapid remyelination.

neuroscience↗

bioRxiv2020

Whole genome comparisons reveal panmixia among fall armyworm (Spodoptera frugiperda) from diverse locations

The fall armyworm (Spodoptera frugiperda (J.E. Smith)) is a highly polyphagous agricultural pest with long-distance migratory behavior threatening food security worldwide. This pest has a host range of >80 plant species, but two host strains are recognized based on their association with corn (C-strain) or rice and smaller grasses (R-strain). In this study, the population structure and genetic diversity in 55 S. frugiperda samples from Argentina, Brazil, Kenya, Puerto Rico and the United States (USA) were surveyed to further our understanding of whole genome nuclear diversity. Comparisons at the genomic level suggest panmixia in this population, other than a minor reduction in gene flow between the two overwintering populations in the continental USA that also corresponded to genetically distinct host strains. Two maternal lines were detected from analysis of mitochondrial genomes. We found members from the Eastern Hemisphere interspersed within both continental USA overwintering subpopulations, suggesting multiple individuals were likely introduced to Africa. Comparisons between laboratory-reared and field collected S. frugiperda support similar genomic diversity, validating the experimental use of laboratory strains. Our research is the largest diverse collection of United States S. frugiperda whole genome sequences characterized to date, covering eight continental states and a USA territory (Puerto Rico). The genomic resources presented provide foundational information to understand gene flow at the whole genome level among S. frugiperda populations.

genomics↗

bioRxiv2019

PANCREATIC ISLETS COMMUNICATE WITH THE BRAIN VIA VAGAL SENSORY NEURONS

Depleting visceral sensory nerves affects pancreatic islet function, glucose metabolism and diabetes onset, but how islet endocrine cells interact with sensory neurons has not been studied. Here we show that the pancreatic islet is innervated by vagal sensory axons expressing substance P, calcitonin-gene related peptide, and serotonin receptor 5HT3R. Vagal neurons projecting to the pancreas terminate in the commissural nucleus of the solitary tract. These neurons respond to chemical but not mechanical stimulation of the pancreas. By recording activity from nodose neurons in vivo and from sensory axons in living pancreas slices, we show that sensory nerves respond to serotonin secreted from stimulated beta cells. Serotonin is co-released with insulin and therefore conveys information about the secretory state of beta cells via vagal afferent nerves. Our study thus establishes that pancreatic islets communicate with the brain using the neural route and identifies serotonin signaling as a peripheral transduction mechanism.

neuroscience↗

bioRxiv2019

Neurofeedback linked suppression of subthalamic beta oscillations speeds up movement initialisation in Parkinsonian Patients

Enhanced beta oscillations (13-30 Hz) in the subthalamic nucleus (STN) have been associated with clinical impairment in Parkinsons disease (PD), such as rigidity and slowing of movement, with the suppression of STN beta activity through medication or deep brain stimulation correlating with improvement in these symptoms. Recent studies have also emphasized the importance of the time dynamics of the STN beta oscillations in the pathology of PD. An increased probability of prolonged beta bursts, defined as periods when beta band power exceeds a certain threshold, was more closely related to motor symptoms than average power; and the occurrence of beta bursts just before a go cue slows cued movements. Here we adopted a sequential neurofeedback-behaviour task paradigm to investigate whether patients with PD can learn to suppress pathological beta oscillations recorded from STN with neurofeedback training and whether the training improves the motor performance. Results from twelve patients showed that, compared with the control condition, the neurofeedback training led to reduced incidence and duration of beta bursts in the STN local field potential (LFP) and also reduced the synchrony between the STN LFP and cortical activities measured through EEG in the beta frequency band. The changes were accompanied by a reduced reaction time in cued movements. These results suggest that volitional suppression of beta bursts facilitated by neurofeedback training could help improve movement initialisation in Parkinsons disease.\n\nSignificance StatementOur study suggests that a neurofeedback paradigm which focuses on the time dynamics of the target neural signal can facilitate volitional suppression of pathological beta oscillations in the STN in Parkinsons disease. Neurofeedback training was accompanied by reduced reaction time in cued movements, but associated with increased tremor in tremulous patients. The results strengthen the link between subthalamic beta oscillations and motor impairment, and also suggest that different symptom-specific neural signals could be targeted to improve neuromodulation strategies, either through brain stimulation or neurofeedback training, for patients with tremor and bradykinesia-rigidity.

neuroscience↗