Neural Decoding and Feature Selection Techniques for Closed-Loop Control of Defensive Behavior.

Objective: Many psychiatric disorders involve excessive avoidant or defensive behavior, such as avoidance in anxiety and trauma disorders or defensive rituals in obsessive-compulsive disorders. Developing algorithms to predict these behaviors from local field potentials (LFPs) could serve as foundational technology for closed-loop control of such disorders. A significant challenge is identifying the LFP features that encode these defensive behaviors. Approach: We analyzed LFP signals from the infralimbic cortex and basolateral amygdala of rats undergoing tone-shock conditioning and extinction, standard for investigating defensive behaviors. We utilized a comprehensive set of neuro-markers across spectral, temporal, and connectivity domains, employing SHapley Additive exPlanations for feature importance evaluation within Light Gradient-Boosting Machine models. Our goal was to decode three commonly studied avoidance/defensive behaviors: freezing, bar-press suppression, and motion (accelerometry), examining the impact of different features on decoding performance. Main results: Band power and band power ratio between channels emerged as optimal features across sessions. High-gamma (80-150 Hz) power, power ratios, and inter-regional correlations were more informative than other bands that are more classically linked to defensive behaviors. Focusing on highly informative features enhanced performance. Across 4 recording sessions with 16 subjects, we achieved an average coefficient of determination of 0.5357 and 0.3476, and Pearson correlation coefficients of 0.7579 and 0.6092 for accelerometry jerk and bar press rate, respectively. Utilizing only the most informative features revealed differential encoding between accelerometry and bar press rate, with the former primarily through local spectral power and the latter via inter-regional connectivity. Our methodology demonstrated remarkably low time complexity, requiring <110 ms for training and <1 ms for inference. Significance: Our results demonstrate the feasibility of accurately decoding defensive behaviors with minimal latency, using LFP features from neural circuits strongly linked to these behaviors. This methodology holds promise for real-time decoding to identify physiological targets in closed-loop psychiatric neuromodulation.

Single-cell heterogeneity of EGFR and CDK4 co-amplification is linked to immune infiltration in glioblastoma.

Glioblastoma (GBM) is the most aggressive brain tumor, with a median survival of ∼15 months. Targeted approaches have not been successful in this tumor type due to the large extent of intratumor heterogeneity. Mosaic amplification of oncogenes suggests that multiple genetically distinct clones are present in each tumor. To uncover the relationships between genetically diverse subpopulations of GBM cells and their native tumor microenvironment, we employ highly multiplexed spatial protein profiling coupled with single-cell spatial mapping of fluorescence in situ hybridization (FISH) for EGFR, CDK4, and PDGFRA. Single-cell FISH analysis of a total of 35,843 single nuclei reveals that tumors in which amplifications of EGFR and CDK4 more frequently co-occur in the same cell exhibit higher infiltration of CD163+ immunosuppressive macrophages. Our results suggest that high-throughput assessment of genomic alterations at the single-cell level could provide a measure for predicting the immune state of GBM.

Regulating Neutrophil PAD4/NOX-Dependent Cerebrovasular Thromboinflammation.

Background: Neutrophil extracellular trap (NET) production has been implicated in the pathogenesis of thromboinflammatory conditions such as Sickle Cell Disease (SCD), contributing to heightened risk for ischemic stroke. NETs are catalyzed by the enzyme Peptidyl Arginine Deiminase 4 (PAD4) and neutrophil derived reactive oxygen species (ROS), especially NADPH oxidase (NOX) which interacts with PAD4 and is therefore critical for neutrophil function. However, the role that NOX-dependent ROS and NETs play in the accelerated cerebral microvascular thrombosis associated with thromboinflammatory conditions, such as SCD, has not been fully elucidated and is the aim of this study. Methods: The in-vitro effects of targeting PAD4 and NOX were examined using physiologically relevant NET assays with neutrophils isolated from healthy volunteers (control) and SCD patients. In addition, in-vivo intravascular effects of targeting PAD4 and NOX in the cerebral microcirculation of C57BL/6 and sickle transgenic mice (STM) were assessed using a photoactivation thrombosis model (light/dye) coupled with real-time fluorescence intravital microscopy. Results: We found that targeting PAD4 and NOX in human neutrophils significantly inhibited ionomycin dependent H3cit+ neutrophils. Targeting PAD4 and NOX in-vivo resulted in prolonged blood flow cessation in cerebrovascular arterioles as well as venules. Moreover, we were able to replicate the effects of PAD4 and NOX targeting in a clinical model of accelerated thromboinflammation by increasing blood flow cessation times in cerebral microvessels in STM. These findings concurred with the clinical setting i.e. neutrophils isolated from SCD patients, which possessed an attenuation of H3cit+ neutrophil production on targeting PAD4 and NOX. Conclusions: Taken together, our compelling data suggests that PAD4 and NOX play a significant role in neutrophil driven thromboinflammation. Targeting PAD4 and NOX limits pathological H3cit+ neutrophils, which may further explain attenuation of cerebral thrombosis. Overall, this study presents a viable pre-clinical model of prevention and management of thromboinflammatory complications such as ischemic stroke.

Skeletal muscle angiogenic, regulatory, and heat shock protein responses to prolonged passive hyperthermia of the human lower limb.

Passive hyperthermia induces a range of physiological responses including augmenting skeletal muscle mRNA expression. This experiment aimed to examine gene and protein responses to prolonged passive leg hyperthermia. Seven young participants underwent 3 h of resting unilateral leg heating (HEAT) followed by a further 3 h of rest, with the contralateral leg serving as an unheated control (CONT). Muscle biopsies were taken at baseline (0 h), and at 1.5, 3, 4, and 6 h in HEAT and 0 and 6 h in CONT to assess changes in selected mRNA expression via qRT-PCR, and HSP72 and VEGFα concentration via ELISA. Muscle temperature (Tm) increased in HEAT plateauing from 1.5 to 3 h (+3.5 ± 1.5°C from 34.2 ± 1.2°C baseline value; P < 0.001), returning to baseline at 6 h. No change occurred in CONT. Endothelial nitric oxide synthase (eNOS), Forkhead box O1 (FOXO-1), Hsp72, and VEGFα mRNA increased in HEAT (P < 0.05); however, post hoc analysis identified that only Hsp72 mRNA statistically increased (at 4 h vs. baseline). When peak change during HEAT was calculated angiopoietin 2 (ANGPT-2) decreased (-0.4 ± 0.2-fold), and C-C motif chemokine ligand 2 (CCL2) (+2.9 ± 1.6-fold), FOXO-1 (+6.2 ± 4.4-fold), Hsp27 (+2.9 ± 1.7-fold), Hsp72 (+8.5 ± 3.5-fold), Hsp90α (+4.6 ± 3.7-fold), and VEGFα (+5.9 ± 3.1-fold) increased from baseline (all P < 0.05). At 6 h Tm were not different between limbs (P = 0.582; CONT = 32.5 ± 1.6°C, HEAT = 34.3 ± 1.2°C), and only ANGPT-2 (P = 0.031; -1.3 ± 1.4-fold) and VEGFα (P = 0.030; 1.1 ± 1.2-fold) differed between HEAT and CONT. No change in VEGFα or HSP72 protein concentration were observed over time; however, peak change in VEGFα did increase (P < 0.05) in HEAT (+140 ± 184 pg·mL-1) versus CONT (+7 ± 86 pg·mL-1). Passive hyperthermia transiently augmented ANGPT-2, CCL2, eNOS, FOXO-1, Hsp27, Hsp72, Hsp90α and VEGFα mRNA, and VEGFα protein.

A Field Primer for Monitoring Benthic Ecosystems using Structure-from-Motion Photogrammetry.

Structure-from-motion (SfM) photogrammetry is a technique used to generate three-dimensional (3D) reconstructions from a sequence of two-dimensional (2D) images. SfM methods are becoming increasingly popular as a noninvasive way to monitor many systems, including anthropogenic and natural landscapes, geologic structures, and both terrestrial and aquatic ecosystems. Here, a detailed protocol is provided for collecting SfM imagery to generate 3D models of benthic habitats. Additionally, the cost, time efficiency, and output quality of employing a Digital Single Lens Reflex (DSLR) camera versus a less expensive action camera have been compared. A tradeoff between computational time and resolution was observed, with the DSLR camera producing models with more than twice the resolution, but taking approximately 1.4-times longer to produce than the action camera. This primer aims to provide a thorough description of the steps necessary to collect SfM data in benthic habitats for those who are unfamiliar with the technique as well as for those already using similar methods.

Wave exposure reduces herbivory in post-disturbed reefs by filtering species composition, abundance and behaviour of key fish herbivores.

Harsh environmental conditions limit how species use the landscape, strongly influencing the way assemblages are distributed. In the wake of repeated coral bleaching mortalities in Lakshadweep, we examined how wave exposure influences herbivory  in exposed and sheltered reefs. We used a combination of i. field observations of fish herbivore composition, abundance and activity across 6 exposed and 6 sheltered reefs; ii. experimental manipulations in a subset of these reefs (herbivore exclosures); and iii. opportunistic observations of fish recruitment, to determine how exposure influences herbivore biomass and herbivory. Species richness, biomass, abundance, total bite rates and species-specific per capita bite rates were lower in exposed compared to sheltered reefs, linked to strong environmental filtering of species composition, abundance and behaviour. For some critical species, this environmental filtering begins with differential recruitment and post-recruitment processes between exposures. Bite rates at sheltered sites were dominated by just a few species, most being laterally compressed surgeonfish that may find it difficult accessing or surviving in wave-battered shallow reefs. Exclosure experiments confirmed  that exposed reefs  were less controlled by herbivores than sheltered reefs. In post-disturbed reefs like Lakshadweep, environmental gradients appear to be key mediators of critical functions like herbivory by determining species composition, abundance and behaviour.

Synthesis of 9-CD3-9-cis-Retinal Cofactor of Isorhodopsin.

We report the synthesis of 9-CD3-9-cis-retinal via a six-step procedure from ß-ionone. The steps involve an initial deuteration of the methyl ketone of ß-ionone followed by two consecutive Horner-Wadsworth-Emmons (HWE) coupling reactions and their corresponding DIBAL reductions. A final oxidation of the allylic alcohol of the retinol leads to the target compound. This deuterium labeled retinoid is an important cofactor for studying protein-retinoid interactions in isorhodopsin.