Parameter inference, an inherently difficult and unresolved problem, poses a major hurdle in the application of such models. Meaningful application of observed neural dynamics and distinctions across experimental settings necessitates the identification of unique parameter distributions. The field of Bayesian inference has seen the recent proposal of simulation-based inference (SBI) for determining parameters within intricate neural models. SBI addresses the absence of a likelihood function, which previously constrained inference methods in these models, by employing deep learning techniques to perform density estimation. Encouraging as SBI's substantial methodological progress may be, its implementation within comprehensive biophysically detailed large-scale models is complex, and systematic methods for this process have not yet been developed, particularly when dealing with parameter inference from time-series waveforms. Starting with a simplified example, we detail guidelines and considerations for applying SBI to estimate time series waveforms in biophysically detailed neural models, progressing to specific applications for common MEG/EEG waveforms within the Human Neocortical Neurosolver's framework. A detailed guide on estimating and comparing the results obtained from example oscillatory and event-related potential simulations is presented. We also provide a detailed description of how diagnostic techniques can be applied to analyze the quality and originality of the calculated posterior estimates. Future applications of SBI, across a wide range of detailed model-driven investigations into neural dynamics, are effectively guided by the principles presented in these methods.
A key hurdle in computational neural modeling lies in the estimation of model parameters that can effectively account for observable neural activity patterns. Several procedures are available for parameter estimation within particular categories of abstract neural models; however, considerably fewer strategies are available for extensive, biophysically accurate neural models. In this research, we describe the obstacles and solutions encountered while utilizing a deep learning-based statistical approach to estimate parameters within a large-scale, biophysically detailed neural model, placing emphasis on the particular challenges posed by time-series data. A multi-scale model, designed to link human MEG/EEG recordings to their underlying cellular and circuit-level sources, is employed in our example. Our methodology offers a critical understanding of how cellular properties interrelate to generate measured neural activity, while also offering direction for assessing the quality of estimates and the uniqueness of predictions for diverse MEG/EEG markers.
One key hurdle in computational neural modeling is finding model parameters that match observed activity patterns. Parameter estimation techniques are abundant for specific kinds of abstract neural models, but these methods face severe limitations when applied to large-scale, biophysically detailed neural networks. Chaetocin The study details the application of a deep learning statistical method to parameter estimation in a detailed large-scale neural model, highlighting the specific difficulties in estimating parameters from time series data and presenting potential solutions. A multi-scale model, designed to correlate human MEG/EEG recordings with the fundamental cellular and circuit-level generators, is used in our example. Crucially, our approach allows us to understand how cell-level properties contribute to measured neural activity, and provides a framework for evaluating the quality and uniqueness of the predictions for diverse MEG/EEG biomarkers.
Local ancestry markers in an admixed population provide a critical understanding of the genetic architecture underpinning complex diseases or traits, as indicated by their heritability. Estimating values can be influenced by the inherent population structures of ancestral groups. A novel heritability estimation method, HAMSTA, is presented, which utilizes admixture mapping summary statistics to infer heritability attributed to local ancestry, accounting for biases introduced by ancestral stratification. Using extensive simulations, we validate that HAMSTA estimates are virtually unbiased and highly robust against ancestral stratification, offering superior performance to existing methodologies. Our results, pertaining to ancestral stratification, reveal that a HAMSTA-based sampling technique offers a calibrated family-wise error rate (FWER) of 5% for admixture mapping, a key distinction from existing FWER estimation approaches. HAMSTA was implemented on the 20 quantitative phenotypes of up to 15,988 self-reported African American participants from the Population Architecture using Genomics and Epidemiology (PAGE) study. Analysis of 20 phenotypes reveals a value range of 0.00025 to 0.0033 (mean), with a corresponding transformation spanning from 0.0062 to 0.085 (mean). Across the range of phenotypes studied, admixture mapping analysis demonstrates minimal inflation resulting from ancestral population stratification; the mean inflation factor is 0.99 ± 0.0001. HAMSTA's approach to assessing genome-wide heritability and identifying biases in test statistics used for admixture mapping is notable for its speed and strength.
Human learning, a multifaceted process exhibiting considerable individual differences, is linked to the internal structure of significant white matter tracts across diverse learning domains, however, the impact of pre-existing myelination within these white matter pathways on future learning outcomes remains poorly understood. We applied a machine-learning model selection framework to assess whether existing microstructure could forecast variations in individual learning potential for a sensorimotor task, and further, whether the correlation between major white matter tracts' microstructure and learning outcomes was specific to those learning outcomes. Fractional anisotropy (FA) of white matter tracts in 60 adult participants was measured via diffusion tractography, subsequently evaluated via learning-based training and testing. Participants, during training, repeatedly practiced drawing a collection of 40 novel symbols on a digital writing tablet. Drawing learning was quantified by the slope of draw duration throughout the practice period, while visual recognition learning was measured by performance accuracy on a 2-AFC recognition task with novel and previously encountered visual stimuli. Results indicated that the microstructure of key white matter tracts exhibited a selective association with learning outcomes. The left hemisphere pArc and SLF 3 tracts were predictive of drawing learning, while the left hemisphere MDLFspl tract was predictive of visual recognition learning. These results were replicated using a separate, held-out dataset and substantiated by concurrent analytical procedures. Chaetocin The results, in their entirety, indicate that variations in the internal structure of human white matter tracts may be uniquely linked to future learning outcomes, necessitating further exploration of the correlation between existing tract myelination and the aptitude for learning.
The murine model has provided evidence of a selective correspondence between tract microstructure and future learning; this relationship has not, to our knowledge, been seen in human subjects. Our data-driven analysis pinpointed two specific areas—the most posterior segments of the left arcuate fasciculus—as predictors of success in a sensorimotor task (drawing symbols), yet this predictive model failed to generalize to other learning measures, such as visual symbol recognition. The observed results point to a potential correlation between individual differences in learning and the properties of crucial white matter tracts in the human cerebral structure.
Mouse models have demonstrated a selective mapping between tract microstructure and future learning; a similar demonstration, to our knowledge, has not yet occurred in humans. Our data-driven approach identified the two most posterior segments of the left arcuate fasciculus, linked to learning a sensorimotor task (drawing symbols). This model's applicability was, however, limited to this task and did not translate to other learning outcomes such as visual symbol recognition. Chaetocin The analysis of the data suggests that variances in individual learning abilities could be selectively tied to the structural properties of the main white matter tracts within the human brain.
Non-enzymatic accessory proteins, expressed by lentiviruses, manipulate cellular machinery within the infected host. Nef, an HIV-1 accessory protein, commandeers clathrin adaptors, leading to the degradation or mislocalization of host proteins critical for antiviral responses. We examine, in genome-edited Jurkat cells, the interplay between Nef and clathrin-mediated endocytosis (CME), a key mechanism for internalizing membrane proteins within mammalian cells, using quantitative live-cell microscopy. CME sites on the plasma membrane experience Nef recruitment, a phenomenon that parallels an increase in the recruitment and persistence of AP-2, a CME coat protein, and, subsequently, dynamin2. Subsequently, we discovered that CME sites which enlist Nef are more predisposed to also enlist dynamin2, hinting that Nef's involvement in CME sites promotes their development into highly effective host protein degradation hubs.
To effectively tailor type 2 diabetes treatment using a precision medicine strategy, it is crucial to pinpoint consistent clinical and biological markers that demonstrably correlate with varying treatment responses to specific anti-hyperglycemic medications. Robustly documented heterogeneity in treatment impacts on type 2 diabetes could potentially guide more personalized clinical decisions regarding the optimal therapy.
We methodically and pre-emptively reviewed meta-analyses, randomized controlled trials, and observational studies to understand the clinical and biological determinants of disparate treatment effects for SGLT2-inhibitors and GLP-1 receptor agonists, as they pertain to glycemic, cardiovascular, and renal health.