Scholarly Works, School of Neuroscience

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Brain Similarity as a Protective Factor in the Longitudinal Pathway Linking Household Chaos, Parenting, and Substance Use
Kim-Spoon, Jungmeen; Lee, Tae-Ho; Clinchard, Claudia; Lindenmuth, Morgan; Brieant, Alexis; Steinberg, Laurence; Deater-Deckard, Kirby; Casas, Brooks (Elsevier, 2023-04-29)
Background: Socioecological factors such as family environment and parenting behaviors contribute to the development of substance use. While biobehavioral synchrony has been suggested as the foundation for resilience that can modulate environmental effects on development, the role of brain similarity that attenuates deleterious effects of environmental contexts has not been clearly understood. We tested whether parent-adolescent neural similarity—the level of pattern similarity between parent-adolescent functional brain connectivity representing the level of attunement within each dyad—moderates the longitudinal pathways in which household chaos (a stressor) predicts adolescent substance use directly and indirectly via parental monitoring. Methods: In a sample of 70 parent-adolescent dyads, similarity in resting-state brain activity was identified using multipattern connectivity similarity estimation. Adolescents and parents reported on household chaos and parental monitoring, and adolescent substance use was assessed at a 1-year follow-up. Results: The moderated mediation model indicated that for adolescents with low neural similarity, but not high neural similarity, greater household chaos predicted higher substance use over time directly and indirectly via lower parental monitoring. Our data also indicated differential susceptibility in the overall association between household chaos and substance use: Adolescents with low neural similarity exhibited high substance use under high household chaos but low substance use under low household chaos. Conclusions: Neural similarity acts as a protective factor such that the detrimental effects of suboptimal family environment and parenting behaviors on the development of adolescent health risk behaviors may be attenuated by neural similarity within parent-adolescent bonds.
Endovascular treatment of a ruptured pure arterial malformation and associated dysplastic middle cerebral artery dissecting aneurysm: illustrative case
Marlow, Christine; Cuoco, Joshua A.; Ravina, Kristine; Sloboda, Cole A.; Entwistle, John J. (Journal of Neurosurgery Publishing Group, 2023-05-22)
BACKGROUND Pure arterial malformations are characterized as unique cerebrovascular lesions with a dilated, coil-like appearance and tortuous arteries without early venous drainage. Historically, these lesions have been described as incidental findings with a benign natural history. However, pure arterial malformations can rarely demonstrate radiographic progression and develop associated focal aneurysms with an unclear risk of rupture. Whether radiographic progression of these lesions or the presence of an associated aneurysm warrants treatment remains controversial. OBSERVATIONS A 58-year-old male presented with sudden-onset left hemiparesis. Computed tomography revealed a large, acute, right frontotemporoparietal intraparenchymal hemorrhage with underlying irregular curvilinear calcifications. Diagnostic cerebral angiography revealed a dysplastic right middle cerebral artery dissecting aneurysm along the M2 segment associated with a pure arterial malformation, which was treated with endovascular flow diversion in a delayed fashion. LESSONS Pure arterial malformations with associated focal aneurysms may not exhibit a benign natural history as once thought. Intervention should be considered for ruptured pure arterial malformations to mitigate the risk of rerupture. Asymptomatic patients with a pure arterial malformation with an associated aneurysm should at least be followed closely with interval radiographic imaging to evaluate for malformation progression or changes in aneurysmal morphology.
Sex-differences in proteasome-dependent K48-polyubiquitin signaling in the amygdala are developmentally regulated in rats
Farrell, Kayla; Auerbach, Aubrey; Liu, Catherine; Martin, Kiley; Pareno, Myasia; Ray, W. Keith; Helm, Richard F.; Biase, Fernando; Jarome, Timothy J. (2023-11-10)
Background Sex differences have been observed in several brain regions for the molecular mechanisms involved in baseline (resting) and memory-related processes. The ubiquitin proteasome system (UPS) is a major protein degradation pathway in cells. Sex differences have been observed in lysine-48 (K48)-polyubiquitination, the canonical degradation mark of the UPS, both at baseline and during fear memory formation within the amygdala. Here, we investigated when, how, and why these baseline sex differences arise and whether both sexes require the K48-polyubiquitin mark for memory formation in the amygdala. Methods We used a combination of molecular, biochemical and proteomic approaches to examine global and protein-specific K48-polyubiquitination and DNA methylation levels at a major ubiquitin coding gene (Uba52) at baseline in the amygdala of male and female rats before and after puberty to determine if sex differences were developmentally regulated. We then used behavioral and genetic approaches to test the necessity of K48-polyubiquitination in the amygdala for fear memory formation. Results We observed developmentally regulated baseline differences in Uba52 methylation and total K48-polyubiquitination, with sexual maturity altering levels specifically in female rats. K48-polyubiquitination at specific proteins changed across development in both male and female rats, but sex differences were present regardless of age. Lastly, we found that genetic inhibition of K48-polyubiquitination in the amygdala of female, but not male, rats impaired fear memory formation. Conclusions These results suggest that K48-polyubiquitination differentially targets proteins in the amygdala in a sex-specific manner regardless of age. However, sexual maturity is important in the developmental regulation of K48-polyubiquitination levels in female rats. Consistent with these data, K48-polyubiquitin signaling in the amygdala is selectively required to form fear memories in female rats. Together, these data indicate that sex-differences in baseline K48-polyubiquitination within the amygdala are developmentally regulated, which could have important implications for better understanding sex-differences in molecular mechanisms involved in processes relevant to anxiety-related disorders such as post-traumatic stress disorder (PTSD).
Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
Soliman, Eman; Leonard, John; Basso, Erwin K. G.; Gershenson, Ilana; Ju, Jing; Mills, Jatia; de Jager, Caroline; Kaloss, Alexandra M.; Elhassanny, Mohamed; Pereira, Daniela; Chen, Michael; Wang, Xia; Theus, Michelle H. (2023-11-09)
Background Efferocytosis is a process that removes apoptotic cells and cellular debris. Clearance of these cells alleviates neuroinflammation, prevents the release of inflammatory molecules, and promotes the production of anti-inflammatory cytokines to help maintain tissue homeostasis. The underlying mechanisms by which this occurs in the brain after injury remain ill-defined. Methods We used GFP bone marrow chimeric knockout (KO) mice to demonstrate that the axon guidance molecule EphA4 receptor tyrosine kinase is involved in suppressing MERTK in the brain to restrict efferocytosis of resident microglia and peripheral-derived monocyte/macrophages. Results Single-cell RNAseq identified MERTK expression, the primary receptor involved in efferocytosis, on monocytes, microglia, and a subset of astrocytes in the damaged cortex following brain injury. Loss of EphA4 on infiltrating GFP-expressing immune cells improved functional outcome concomitant with enhanced efferocytosis and overall protein expression of p-MERTK, p-ERK, and p-Stat6. The percentage of GFP+ monocyte/macrophages and resident microglia engulfing NeuN+ or TUNEL+ cells was significantly higher in KO chimeric mice. Importantly, mRNA expression of Mertk and its cognate ligand Gas6 was significantly elevated in these mice compared to the wild-type. Analysis of cell-specific expression showed that p-ERK and p-Stat6 co-localized with MERTK-expressing GFP + cells in the peri-lesional area of the cortex following brain injury. Using an in vitro efferocytosis assay, co-culturing pHrodo-labeled apoptotic Jurkat cells and bone marrow (BM)-derived macrophages, we demonstrate that efferocytosis efficiency and mRNA expression of Mertk and Gas6 was enhanced in the absence of EphA4. Selective inhibitors of ERK and Stat6 attenuated this effect, confirming that EphA4 suppresses monocyte/macrophage efferocytosis via inhibition of the ERK/Stat6 pathway. Conclusions Our findings implicate the ERK/Stat6/MERTK axis as a novel regulator of apoptotic debris clearance in brain injury that is restricted by peripheral myeloid-derived EphA4 to prevent the resolution of inflammation.
Remdesivir increases mtDNA copy number causing mild alterations to oxidative phosphorylation
DeFoor, Nicole; Paul, Swagatika; Li, Shuang; Basso, Erwin K. Gudenschwager; Stevenson, Valentina; Browning, Jack L.; Prater, Anna K.; Brindley, Samantha; Tao, Ge; Pickrell, Alicia M. (Springer, 2023-12-01)
SARS-CoV-2 causes the severe respiratory disease COVID-19. Remdesivir (RDV) was the first fast-tracked FDA approved treatment drug for COVID-19. RDV acts as an antiviral ribonucleoside (adenosine) analogue that becomes active once it accumulates intracellularly. It then diffuses into the host cell and terminates viral RNA transcription. Previous studies have shown that certain nucleoside analogues unintentionally inhibit mitochondrial RNA or DNA polymerases or cause mutational changes to mitochondrial DNA (mtDNA). These past findings on the mitochondrial toxicity of ribonucleoside analogues motivated us to investigate what effects RDV may have on mitochondrial function. Using in vitro and in vivo rodent models treated with RDV, we observed increases in mtDNA copy number in Mv1Lu cells (35.26% increase ± 11.33%) and liver (100.27% increase ± 32.73%) upon treatment. However, these increases only resulted in mild changes to mitochondrial function. Surprisingly, skeletal muscle and heart were extremely resistant to RDV treatment, tissues that have preferentially been affected by other nucleoside analogues. Although our data suggest that RDV does not greatly impact mitochondrial function, these data are insightful for the treatment of RDV for individuals with mitochondrial disease.
Sex differences in depression: An immunological perspective
Kropp, Dawson R.; Hodes, Georgia E. (Pergamon-Elsevier, 2023-05)
Depression is a heterogenous disorder with symptoms that present differently across individuals. In a subset of people depression is associated with alterations of the immune system that may contribute to disorder onset and symptomology. Women are twice as likely to develop depression and on average have a more sensitive adaptive and innate immune system when compared to men. Sex differences in pattern recognition receptors (PRRs), release of damage-associated molecular patterns (DAMPs), cell populations, and circulating cytokines play a critical role in inflammation onset. Sex differences in innate and adaptive immunity change the response of and repair to damage caused by dangerous pathogens or molecules in the body. This article reviews the evidence for sex specific immune responses that contribute to the sex differences in symptoms of depression that may account for the higher rate of depression in women.
3D electron microscopy and volume-based bouton sorting reveal the selectivity of inputs onto geniculate relay cell and interneuron dendrite segments
Maher, Erin E.; Briegel, Alex C.; Imtiaz, Shahrozia; Fox, Michael A.; Golino, Hudson; Erisir, Alev (Frontiers, 2023-03)
IntroductionThe visual signals evoked at the retinal ganglion cells are modified and modulated by various synaptic inputs that impinge on lateral geniculate nucleus cells before they are sent to the cortex. The selectivity of geniculate inputs for clustering or forming microcircuits on discrete dendritic segments of geniculate cell types may provide the structural basis for network properties of the geniculate circuitry and differential signal processing through the parallel pathways of vision. In our study, we aimed to reveal the patterns of input selectivity on morphologically discernable relay cell types and interneurons in the mouse lateral geniculate nucleus. MethodsWe used two sets of Scanning Blockface Electron Microscopy (SBEM) image stacks and Reconstruct software to manually reconstruct of terminal boutons and dendrite segments. First, using an unbiased terminal sampling (UTS) approach and statistical modeling, we identified the criteria for volume-based sorting of geniculate boutons into their putative origins. Geniculate terminal boutons that were sorted in retinal and non-retinal categories based on previously described mitochondrial morphology, could further be sorted into multiple subpopulations based on their bouton volume distributions. Terminals deemed non-retinal based on the morphological criteria consisted of five distinct subpopulations, including small-sized putative corticothalamic and cholinergic boutons, two medium-sized putative GABAergic inputs, and a large-sized bouton type that contains dark mitochondria. Retinal terminals also consisted of four distinct subpopulations. The cutoff criteria for these subpopulations were then applied to datasets of terminals that synapse on reconstructed dendrite segments of relay cells or interneurons. ResultsUsing a network analysis approach, we found an almost complete segregation of retinal and cortical terminals on putative X-type cell dendrite segments characterized by grape-like appendages and triads. On these cells, interneuron appendages intermingle with retinal and other medium size terminals to form triads within glomeruli. In contrast, a second, presumed Y-type cell displayed dendrodendritic puncta adherentia and received all terminal types without a selectivity for synapse location; these were not engaged in triads. Furthermore, the contribution of retinal and cortical synapses received by X-, Y- and interneuron dendrites differed such that over 60% of inputs to interneuron dendrites were from the retina, as opposed to 20% and 7% to X- and Y-type cells, respectively. ConclusionThe results underlie differences in network properties of synaptic inputs from distinct origins on geniculate cell types.
Pediatric diffuse hemispheric glioma H3 G34-mutant with gains of the BRAF locus: An illustrative case
Marlow, Christine; Cuoco, Joshua A.; Hoggarth, Austin R.; Stump, Michael S.; Apfel, Lisa S.; Rogers, Cara M. (SAGE, 2023-03)
Diffuse hemispheric glioma, H3 G34-mutant, is a recently recognized distinct high-grade glioma with a dismal prognosis. In addition to the H3 G34 missense mutation, numerous genetic events have been identified in these malignant tumors, including ATRX, TP53, and, rarely, BRAF genes. There are only a few reports to date that have identified BRAF mutations in diffuse hemispheric glioma, H3 G34-mutant. Moreover, to our knowledge, gains of the BRAF locus have yet to be described. Here, we present a case of an 11-year-old male with a diffuse hemispheric glioma, H3 G34-mutant, found to have novel gains of the BRAF locus. Furthermore, we emphasize the current genetic landscape of diffuse hemispheric glioma, H3 G34-mutant, and implications of an aberrant BRAF signaling pathway.
Unsupervised Multitaper Spectral Method for Identifying REM Sleep in Intracranial EEG Recordings Lacking EOG/EMG Data
Lepage, Kyle Q.; Jain, Sparsh; Kvavilashvili, Andrew; Witcher, Mark; Vijayan, Sujith (MDPI, 2023-08-25)
A large number of human intracranial EEG (iEEG) recordings have been collected for clinical purposes, in institutions all over the world, but the vast majority of these are unaccompanied by EOG and EMG recordings which are required to separate Wake episodes from REM sleep using accepted methods. In order to make full use of this extremely valuable data, an accurate method of classifying sleep from iEEG recordings alone is required. Existing methods of sleep scoring using only iEEG recordings accurately classify all stages of sleep, with the exception that wake (W) and rapid-eye movement (REM) sleep are not well distinguished. A novel multitaper (Wake vs. REM) alpha-rhythm classifier is developed by generalizing K-means clustering for use with multitaper spectral eigencoefficients. The performance of this unsupervised method is assessed on eight subjects exhibiting normal sleep architecture in a hold-out analysis and is compared against a classical power detector. The proposed multitaper classifier correctly identifies 36±6 min of REM in one night of recorded sleep, while incorrectly labeling less than 10% of all labeled 30 s epochs for all but one subject (human rater reliability is estimated to be near 80%), and outperforms the equivalent statistical-power classical test. Hold-out analysis indicates that when using one night’s worth of data, an accurate generalization of the method on new data is likely. For the purpose of studying sleep, the introduced multitaper alpha-rhythm classifier further paves the way to making available a large quantity of otherwise unusable IEEG data.
Biomolecules Triggering Altered Food Intake during Pathogenic Challenge in Chicks
Tachibana, Tetsuya; Cline, Mark A. (Japan Poultry Science Association, 2023-04)
Food intake is regulated by several complicated synergistic mechanisms that are affected by a variety of internal and ex-ternal influences. Some of these factors include those that are released from pathogens such as bacteria, fungi, and viruses, and most of these factors are associated with suppression of the chick's food intake. Although chicks are well-known to decrease their food intake when they experience a pathogenic challenge, the mechanisms that mediate this type of satiety are poorly understood. One of the goals of our research group has been to better understand these mechanisms in chicks. We recently provided evidence that pathogen-associated molecular patterns, which are recognized by pattern-recognition receptors such as Toll-like receptors, likely contribute to satiety in chicks that are experiencing a pathogenic challenge. Additionally, we identified several inflammatory cytokines, including interleukin-1 beta, tumor necrosis factor-like cytokine 1A, prostaglandins, and nitric oxide, that likely contribute to satiety during a pathogenic challenge. This review summarizes the current knowl-edge on pathogen-induced satiety in chicks mainly accumulated through our recent research. The research will give good information to improve the loss of production during infection in poultry production in the future.
Collagen XIX is required for pheromone recognition and glutamatergic synapse formation in mouse accessory olfactory bulb
Amos, Chase; Fox, Michael A.; Su, Jianmin (Frontiers, 2023-04)
In mammals, the accessory olfactory bulb (AOB) receives input from vomeronasal sensory neurons (VSN) which detect pheromones, chemical cues released by animals to regulate the physiology or behaviors of other animals of the same species. Cytoarchitecturally, cells within the AOB are segregated into a glomerular layer (GL), mitral cell layer (MCL), and granule cell layer (GCL). While the cells and circuitry of these layers has been well studied, the molecular mechanism underlying the assembly of such circuitry in the mouse AOB remains unclear. With the goal of identifying synaptogenic mechanisms in AOB, our attention was drawn to Collagen XIX, a non-fibrillar collagen generated by neurons in the mammalian telencephalon that has previously been shown to regulate the assembly of synapses. Here, we used both a targeted mouse mutant that lacks Collagen XIX globally and a conditional allele allowing for cell-specific deletion of this collagen to test if the loss of Collagen XIX causes impaired synaptogenesis in the mouse AOB. These analyses not only revealed defects in excitatory synapse distribution in these Collagen XIX-deficient mutants, but also showed that these mutant mice exhibit altered behavioral responses to pheromones. Although this collagen has been demonstrated to play synaptogenic roles in the telencephalon, those roles are at perisomatic inhibitory synapses, results here are the first to demonstrate the function of this unconventional collagen in glutamatergic synapse formation.
Controlling hypothalamic DNA methylation at the Pomc promoter does not regulate weight gain during the development of obesity
McFadden, Taylor; Gaito, Natasha; Carucci, Isabella; Fletchall, Everett; Farrell, Kayla; Jarome, Timothy J. (Public Library of Science, 2023-04)
Obesity is a complex medical condition that is linked to various health complications such as infertility, stroke, and osteoarthritis. Understanding the neurobiology of obesity is crucial for responding to the etiology of this disease. The hypothalamus coordinates many integral activities such as hormone regulation and feed intake and numerous studies have observed altered hypothalamic gene regulation in obesity models. Previously, it was reported that the promoter region of the satiety gene, Pomc, has increased DNA methylation in the hypothalamus following short-term exposure to a high fat diet, suggesting that epigenetic-mediated repression of hypothalamic Pomc might contribute to the development of obesity. However, due to technical limitations, this has never been directly tested. Here, we used the CRISPR-dCas9-TET1 and dCas9-DNMT3a systems to test the role of Pomc DNA methylation in the hypothalamus in abnormal weight gain following acute exposure to a high fat diet in male rats. We found that exposure to a high fat diet increases Pomc DNA methylation and reduces gene expression in the hypothalamus. Despite this, we found that CRISPR-dCas9-TET1-mediated demethylation of Pomc was not sufficient to prevent abnormal weight gain following exposure to a high fat diet. Furthermore, CRISPR-dCas9-DNMT3a-mediated methylation of Pomc did not alter weight gain following exposure to standard or high fat diets. Collectively, these results suggest that high fat diet induced changes in Pomc DNA methylation are a consequence of, but do not directly contribute to, abnormal weight gain during the development of obesity.
Sex as a biological variable in stress and mood disorder research
Hodes, Georgia E.; Kropp, Dawson R. (Springer Nature, 2023-07)
In 2016, changes were mandated for basic research, including using sex as a biological variable. This policy change was due to the lack of research performed in female animals. This resulted in a mismatch between the sex of the subjects being used for drug development and the sex of the participants in subsequent clinical trials hampering the translational success of novel therapeutics, especially treatments for mood disorders. While it is now clear that sex differences exist, the field needs to move to the next frontier in sex-difference research. We need to start exploring why and how these sex differences exist. What are their functions? How do we harness this information to develop novel sex-specific treatments for mental illness? This Review will address what we have learned from using sex as a biological variable and how we can utilize these data to better understand and treat sex-based disparities in mental health.
Sex-Linked Growth Disorder and Aberrant Pituitary Gene Expression in Nestin-Cre-Mediated Egr1 Conditional Knockout Mice
Swilley, Cody; Lin, Yu; Zheng, Yuze; Xu, Xiguang; Liu, Min; Zimmerman, Kurt; Xie, Hehuang (MDPI, 2023-07-06)
Genes that regulate hormone release are essential for maintaining metabolism and energy balance. Egr1 encodes a transcription factor that regulates hormone production and release, and a decreased in growth hormones has been reported in Egr1 knockout mice. A reduction in growth hormones has also been observed in Nestin-Cre mice, a model frequently used to study the nervous system. Currently, it is unknown how Egr1 loss or the Nestin-Cre driver disrupt pituitary gene expression. Here, we compared the growth curves and pituitary gene expression profiles of Nestin-Cre-mediated Egr1 conditional knockout (Egr1cKO) mice with those of their controls. Reduced body weight was observed in both the Nestin-Cre and Egr1cKO mice, and the loss of Egr1 had a slightly more severe impact on female mice than on male mice. RNA-seq data analyses revealed that the sex-related differences were amplified in the Nestin-Cre-mediated Egr1 conditional knockout mice. Additionally, in the male mice, the influence of Egr1cKO on pituitary gene expression may be overridden by the Nestin-Cre driver. Differentially expressed genes associated with the Nestin-Cre driver were significantly enriched for genes related to growth factor activity and binding. Altogether, our results demonstrate that Nestin-Cre and the loss of Egr1 in the neuronal cell lineage have distinct impacts on pituitary gene expression in a sex-specific manner.
Peripheral and Central Impact of Methionine Source and Level on Growth Performance, Circulating Methionine Levels and Metabolism in Broiler Chickens
Maynard, Craig W.; Gilbert, Elizabeth; Yan, Frances; Cline, Mark A.; Dridi, Sami (MDPI, 2023-06-12)
The present study was designed to evaluate the effects of DL-methionine (DL-Met) 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), or S-(5′-Adenosyl)-L-methionine chloride (SAM), using feeding trial and central administration, on live performance, plasma metabolites, and the expression of feeding-related hypothalamic neuropeptides in broilers raised to a market age (35 d). Final average body weight (BW) and feed conversion ratio (FCR) from the feeding trial exceeded the performance measurements published by the primary breeder. At d35, the MTBHa group had better BW and lower feed intake, which resulted in a better FCR than the DL-Met group at 87 TSAA to lysine. At the molecular levels, the expression of hypothalamic neuropeptide (NPY) and monocarboxylate transporter (MCT) 2 did not differ between all treated groups; however, the mRNA abundances of hypothalamic MCT1 and orexin (ORX) were significantly upregulated in DL-Met- treated groups compared to the control. The ICV administration of SAM significantly reduced feed intake at all tested periods (from 30 to 180 min post injection) compared to the aCSF-treated group (control). The central administration of HMTBa increased feed intake, which reached a significant level only 60 min post administration, compared to the control group. ICV administration of DL-Met slightly increased feed intake compared to the control group, but the difference was not statistically discernable. Quantitative real-time PCR analysis showed that the hypothalamic expression of NPY, cocaine- and amphetamine-regulated transcript, MCT1, and MCT2 was significantly upregulated in the ICV-HMTBa group compared to the aCSF birds. The hypothalamic expression of the mechanistic target of rapamycin (mTOR), AMP-activated protein kinase (AMPKα1), D-amino acid oxidase, and hydroxyacid oxidase was significantly upregulated in DL-Met compared to the control group. The mRNA abundances of ORX were significantly increased in the hypothalamus of both DL-Met and HMTBa groups compared to the aCSF birds; however, mTOR gene expression was significantly downregulated in the SAM compared to the control group. Taken together, these data show, for the first time, that DL-Met and HMTBa have a common downstream (ORX) pathway, but also a differential central pathway, typically NPY-MCT for HMTBa and mTOR-AMPK for methionine.
Evidence for Using ACQUIRE Therapy in the Clinical Application of Intensive Therapy: A Framework to Guide Therapeutic Interactions
DeLuca, Stephanie C.; Trucks, Mary Rebekah; Wallace, Dorian; Ramey, Sharon L. (MDPI, 2023-06-07)
Intensive therapies have become increasingly popular for children with hemiparesis in the last two decades and are specifically recommended because of high levels of scientific evidence associated with them, including multiple randomized controlled trials and systematic reviews. Common features of most intensive therapies that have documented efficacy include: high dosages of therapy hours; active engagement of the child; individualized goal-directed activities; and the systematic application of operant conditioning techniques to elicit and progress skills with an emphasis on success-oriented play. However, the scientific protocols have not resulted in guiding principles designed to aid clinicians with understanding the complexity of applying these principles to a heterogeneous clinical population, nor have we gathered sufficient clinical data using intensive therapies to justify their widespread clinical use beyond hemiparesis. We define a framework for describing moment-by-moment therapeutic interactions that we have used to train therapists across multiple clinical trials in implementing intensive therapy protocols. We also document outcomes from the use of this framework during intensive therapies provided clinically to children (7 months–20 years) from a wide array of diagnoses that present with motor impairments, including hemiparesis and quadriparesis. Results indicate that children from a wide array of diagnostic categories demonstrated functional improvements.
Atypical Neurogenesis, Astrogliosis, and Excessive Hilar Interneuron Loss Are Associated with the Development of Post-Traumatic Epilepsy
Gudenschwager-Basso, Erwin Kristobal; Shandra, Oleksii; Volanth, Troy; Patel, Dipan C.; Kelly, Colin; Browning, Jack L.; Wei, Xiaoran; Harris, Elizabeth A.; Mahmutovic, Dzenis; Kaloss, Alexandra M.; Correa, Fernanda Guilhaume; Decker, Jeremy; Maharathi, Biswajit; Robel, Stefanie; Sontheimer, Harald; VandeVord, Pamela J.; Olsen, Michelle L.; Theus, Michelle H. (MDPI, 2023-04-25)
Background: Traumatic brain injury (TBI) remains a significant risk factor for post-traumatic epilepsy (PTE). The pathophysiological mechanisms underlying the injury-induced epileptogenesis are under investigation. The dentate gyrus—a structure that is highly susceptible to injury—has been implicated in the evolution of seizure development. Methods: Utilizing the murine unilateral focal control cortical impact (CCI) injury, we evaluated seizure onset using 24/7 EEG video analysis at 2–4 months post-injury. Cellular changes in the dentate gyrus and hilus of the hippocampus were quantified by unbiased stereology and Imaris image analysis to evaluate Prox1-positive cell migration, astrocyte branching, and morphology, as well as neuronal loss at four months post-injury. Isolation of region-specific astrocytes and RNA-Seq were performed to determine differential gene expression in animals that developed post-traumatic epilepsy (PTE⁺) vs. those animals that did not (PTE⁻), which may be associated with epileptogenesis. Results: CCI injury resulted in 37% PTE incidence, which increased with injury severity and hippocampal damage. Histological assessments uncovered a significant loss of hilar interneurons that coincided with aberrant migration of Prox1-positive granule cells and reduced astroglial branching in PTE⁺ compared to PTE⁻ mice. We uniquely identified Cst3 as a PTE⁺-specific gene signature in astrocytes across all brain regions, which showed increased astroglial expression in the PTE⁺ hilus. Conclusions: These findings suggest that epileptogenesis may emerge following TBI due to distinct aberrant cellular remodeling events and key molecular changes in the dentate gyrus of the hippocampus.
Cortical circuit-based lossless neural integrator for perceptual decision-making: A computational modeling study
Lee, Jung Hoon; Tsunada, Joji; Vijayan, Sujith; Cohen, Yale E. (Frontiers, 2022-11)
The intrinsic uncertainty of sensory information (i.e., evidence) does not necessarily deter an observer from making a reliable decision. Indeed, uncertainty can be reduced by integrating (accumulating) incoming sensory evidence. It is widely thought that this accumulation is instantiated via recurrent rate-code neural networks. Yet, these networks do not fully explain important aspects of perceptual decision-making, such as a subject's ability to retain accumulated evidence during temporal gaps in the sensory evidence. Here, we utilized computational models to show that cortical circuits can switch flexibly between "retention" and "integration" modes during perceptual decision-making. Further, we found that, depending on how the sensory evidence was readout, we could simulate "stepping" and "ramping" activity patterns, which may be analogous to those seen in different studies of decision-making in the primate parietal cortex. This finding may reconcile these previous empirical studies because it suggests these two activity patterns emerge from the same mechanism.
Sonic hedgehog-dependent recruitment of GABAergic interneurons into the developing visual thalamus
Somaiya, Rachana Deven; Stebbins, Katelyn; Gingrich, Ellen C.; Xie, Hehuang; Campbell, John N.; Garcia, A. Denise R.; Fox, Michael A. (Elife Sciences, 2022-11)
Axons of retinal ganglion cells (RGCs) play critical roles in the development of inhibitory circuits in visual thalamus. We previously reported that RGC axons signal astrocytes to induce the expression of fibroblast growth factor 15 (FGF15), a motogen required for GABAergic interneuron migration into visual thalamus. However, how retinal axons induce thalamic astrocytes to generate Fgf15 and influence interneuron migration remains unknown. Here, we demonstrate that impairing RGC activity had little impact on interneuron recruitment into mouse visual thalamus. Instead, our data show that retinal-derived sonic hedgehog (SHH) is essential for interneuron recruitment. Specifically, we show that thalamus-projecting RGCs express SHH and thalamic astrocytes generate downstream components of SHH signaling. Deletion of RGC-derived SHH leads to a significant decrease in Fgf15 expression, as well as in the percentage of interneurons recruited into visual thalamus. Overall, our findings identify a morphogen-dependent neuron-astrocyte signaling mechanism essential for the migration of thalamic interneurons.
Cool and warm ionotropic receptors control multiple thermotaxes in Drosophila larvae
Omelchenko, Alisa A.; Bai, Hua; Spina, Emma C.; Tyrrell, Jordan J.; Wilbourne, Jackson T.; Ni, Lina (Frontiers, 2022-11)
Animals are continuously confronted with different rates of temperature variation. The mechanism underlying how temperature-sensing systems detect and respond to fast and slow temperature changes is not fully understood in fly larvae. Here, we applied two-choice behavioral assays to mimic fast temperature variations and a gradient assay to model slow temperature changes. Previous research indicates that Rhodopsin 1 (Rh1) and its phospholipase C (PLC) cascade regulate fast and slow temperature responses. We focused on the ionotropic receptors (IRs) expressed in dorsal organ ganglions (DOG), in which dorsal organ cool-activated cells (DOCCs) and warm-activated cells (DOWCs) rely on IR-formed cool and warm receptors to respond to temperature changes. In two-choice assays, both cool and warm IRs are sufficient for selecting 18 degrees C between 18 degrees C and 25 degrees C but neither function in cool preferences between 25 degrees C and 32 degrees C. The Rh1 pathway, on the other hand, contributes to choosing preferred temperatures in both assays. In a gradient assay, cool and warm IR receptors exert opposite effects to guide animals to similar to 25 degrees C. Cool IRs drive animals to avoid cool temperatures, whereas warm IRs guide them to leave warm regions. The Rh1 cascade and warm IRs may function in the same pathway to drive warm avoidance in gradient assays. Moreover, IR92a is not expressed in temperature-responsive neurons but regulates the activation of DOWCs and the deactivation of DOCCs. Together with previous studies, we conclude that multiple thermosensory systems, in various collaborative ways, help larvae to make their optimal choices in response to different rates of temperature change.

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