Jul 2026· International Journal of Molecular Sciences· Vol 27, pp. 6083· 0 citations· 63 references
Medicine
TL;DR
Two representations of cross-context brain transcriptomic organization are compared: a transcriptome-wide global-axis model and a low-dimensional reciprocal model, motivating a low-dimensional reciprocal representation as an exploratory framework while emphasizing context dependence, cohort dependence, and heterogeneity.
Abstract
Adaptive and adverse brain states are often assumed to lie on a shared molecular continuum, but this assumption has rarely been evaluated against explicit transcriptomic alternatives. This study aimed to compare two representations of cross-context brain transcriptomic organization: a transcriptome-wide global-axis model and a low-dimensional reciprocal model. We benchmarked these models across a curated cross-study brain cohort spanning exercise, alcohol-related adversity-like contexts, stress, aging, and neurodegeneration, using prespecified intervention-like and adversity-like directional contrast labels rather than assuming homogeneous biological states. We assessed the competing representations using signed-effect correlations, permutation analyses, non-linear fitting, and held-out reconstruction, and we then examined the resulting structure through region-specific human bulk evaluation and exploratory cellular, single-nucleus, spatial, and chromatin projection analyses. These downstream analyses were used to examine localization and biological interpretability and were not treated as independent evaluation of the module 1/module 2 (M1/M2) partition. The combined signed-effect statistics were interpreted as representation-level directional summaries rather than estimates of a homogeneous cross-study biological effect. The global-axis model received limited support: intervention-like and adversity-like signed-effect summaries were only weakly correlated, were not stronger than permutation null expectations, and were not improved by non-linear fitting. Within the selected reciprocal-gene space, a rank-1 latent profile reconstructed held-out genes more accurately than the hard M1/M2 partition, whereas the M1/M2 discretization provided a more interpretable but selection-conditioned directional summary. Human analyses yielded an asymmetric pattern: a significant M1 association was observed only in the hippocampal dataset, whereas M2, the reciprocal index, and the other examined brain regions showed no consistent corresponding effects; leave-one-stratum-out analyses indicated poor cross-stratum reproducibility of the exact gene-level partition. These findings motivate a low-dimensional reciprocal representation as an exploratory framework while emphasizing context dependence, cohort dependence, and heterogeneity.
A spatial transcriptomic atlas of the human amygdala from nine neurotypical donors provides a foundational resource and framework for accelerating cross-species comparisons and human disease-focused investigations.
Michael S. Totty, Svitlana V. Bach, Madeline R. Valentine et al.· bioRxiv· 0 citations
Interindividual heterogeneity in Alzheimer’s disease (AD) remains poorly understood, as disparate single-cell studies leave it unclear whether findings reflect shared architecture or dataset-specific idiosyncrasies. Here, we present panAD, a transcriptomic atlas of >3 million nuclei from 791 individuals across 13 studies, spanning AD, mild cognitive impairment, and cognitively normal aging. AD converges on a reproducible, cell-type-specific molecular architecture: co-expression modules track neuropathology and cognitive decline; GWAS risk genes act predominantly as downstream targets of transcription factor hubs such as microglial SPI1; intercellular communication is remodeled with disease stage; and sex differences concentrate in microglial immune-activation programs. To model patient-level transcriptomic heterogeneity, we developed the Multi-seed Optimization of Neural Embeddings for subTyping (MONET) framework, in which a masked variational autoencoder applied to covariate-adjusted, multi-cell-type profiles resolves four subtypes (Metal-Ion Stress, Neuroinflammatory, Synaptic Integrity, and Tissue Remodeling) that dissociate neuropathological burden from cognitive impairment and nominate predominantly non-overlapping candidate therapeutics. Finally, Stellar Atlas provides an AI-native conversational interface to the atlas.
Negin Rahimzadeh, S. Morabito, Saniya Khullar et al.· bioRxiv· 0 citations
Despite substantial advances in genomic testing, many individuals with neurodevelopmental disorders remain without a molecular diagnosis, while others receive a genetic diagnosis that does not fully explain phenotypic variability, developmental trajectory or tissue-specific consequences. Artificial intelligence (AI)-assisted methods are increasingly used for phenotyping, variant prioritisation, splice prediction, protein modelling, DNA methylation episignature classification and multi-omic analysis. However, these approaches differ substantially in evidentiary status and are often applied as separate prediction tasks rather than as components of an explicit mechanistic model. In this targeted narrative review, focused primarily on rare and genetically enriched neurodevelopmental disorders, we examine how AI-assisted methods may contribute to systems-level interpretation while remaining anchored to established molecular diagnosis and variant-classification frameworks. We propose a hypothesis-generating load-capacity framework comprising regulatory load, network capacity, developmental buffering and regulatory network instability. These are treated as operationalisable but currently unvalidated constructs. Regulatory instability is distinguished from stable disease-associated dysregulation, and threshold-like behaviour is presented as an empirical possibility rather than an assumed property of neurodevelopmental disease. We formulate five falsifiable predictions, consider how genomic, transcriptomic, epigenomic, single-cell, spatial, imaging, neurophysiological and longitudinal phenotypic evidence can provide complementary mechanistic constraints, and outline an auditable workflow following nondiagnostic genomic testing. We distinguish clinically implemented approaches from translational, emerging and conceptual applications, and emphasise calibration, evidence traceability, domain validity, prospective validation and appropriate abstention. Finally, we describe the Instability Twin as a prospective architecture composed of independently testable patient-specific sub-models rather than an existing clinical platform. The central proposition is that systems neurogenomics should be evaluated by whether mechanistically constrained integration provides reproducible information beyond established gene-level and simpler multimodal approaches.
Himanshu Goel, Tracy Dudding-Byth, B. Kamien· Genes· 0 citations
Understanding which genes are reproducibly dysregulated in which cell types is foundational knowledge for efforts to slow or reverse pathologies. For neuropathologies, such efforts rely primarily on differential expression analysis of single-nucleus RNA-seq (snRNA-seq) data. However, this strategy suffers from experimental and statistical challenges that limit marker gene reproducibility. We describe a novel strategy called Covariation Projection Analysis (CoPA) that combines the power of bulk sampling with the precision of single-cell methods. By ‘projecting’ bulk gene coexpression modules onto pseudobulked snRNA-seq cell types, CoPA reveals the cellular origins of highly reproducible genomic programs and their relative importance among cell types. By comparing CoPA projection patterns between normal and pathological human brain samples using differential CoPA (dCoPA), we identify gene coexpression modules that are uniformly and reproducibly dysregulated in specific neocortical cell types in Alzheimer’s disease or schizophrenia. We share our findings through a novel web application called CoPA Cabana (https://oldhamlab.shinyapps.io/copacabana/).
Gugene Kang, M. Oldham· bioRxiv· 0 citations
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