Portrait of Smita Krishnaswamy

Smita Krishnaswamy

Affiliate Member
Associate Professor, Yale University
Université de Montréal
Yale
Research Topics
AI in Health
Brain-computer Interfaces
Cognitive Science
Computational Biology
Computational Neuroscience
Data Geometry
Data Science
Data Sparsity
Deep Learning
Dynamical Systems
Generative Models
Geometric Deep Learning
Graph Neural Networks
Information Theory
Manifold Learning
Molecular Modeling
Representation Learning
Spectral Learning

Biography

Our lab works on developing foundational mathematical machine learning and deep learning methods that incorporate graph-based learning, signal processing, information theory, data geometry and topology, optimal transport and dynamics modeling that are capable of exploratory analysis, scientific inference, interpretation and hypothesis generation big biomedical datasets ranging from single-cell data, to brain imaging, to molecular structural datasets arising from neuroscience, psychology, stem cell biology, cancer biology, healthcare, and biochemistry. Our works have been instrumental in dynamic trajectory learning from static snapshot data, data denoising, visualization, network inference, molecular structure modeling and more.

Publications

Accelerated learning of a noninvasive human brain-computer interface via manifold geometry
Erica Lindsey Busch
E. Chandra Fincke
Nicholas B Turk-Browne
HiPoNet: A Topology-Preserving Multi-View Neural Network For High Dimensional Point Cloud and Single-Cell Data
Siddharth Viswanath
Hiren Madhu
Dhananjay Bhaskar
Jake Kovalic
David R. Johnson
Rex Ying
Christopher Tape
Ian Adelstein
Michael Perlmutter
In this paper, we propose HiPoNet, an end-to-end differentiable neural network for regression, classification, and representation learning o… (see more)n high-dimensional point clouds. Single-cell data can have high dimensionality exceeding the capabilities of existing methods point cloud tailored for 3D data. Moreover, modern single-cell and spatial experiments now yield entire cohorts of datasets (i.e. one on every patient), necessitating models that can process large, high-dimensional point clouds at scale. Most current approaches build a single nearest-neighbor graph, discarding important geometric information. In contrast, HiPoNet forms higher-order simplicial complexes through learnable feature reweighting, generating multiple data views that disentangle distinct biological processes. It then employs simplicial wavelet transforms to extract multi-scale features - capturing both local and global topology. We empirically show that these components preserve topological information in the learned representations, and that HiPoNet significantly outperforms state-of-the-art point-cloud and graph-based models on single cell. We also show an application of HiPoNet on spatial transcriptomics datasets using spatial co-ordinates as one of the views. Overall, HiPoNet offers a robust and scalable solution for high-dimensional data analysis.
HiPoNet: A Topology-Preserving Multi-View Neural Network For High Dimensional Point Cloud and Single-Cell Data
Siddharth Viswanath
Hiren Madhu
Dhananjay Bhaskar
Jake Kovalic
Dave Johnson
Rex Ying
Christopher Tape
Ian Adelstein
Michael Perlmutter
In this paper, we propose HiPoNet, an end-to-end differentiable neural network for regression, classification, and representation learning o… (see more)n high-dimensional point clouds. Single-cell data can have high dimensionality exceeding the capabilities of existing methods point cloud tailored for 3D data. Moreover, modern single-cell and spatial experiments now yield entire cohorts of datasets (i.e. one on every patient), necessitating models that can process large, high-dimensional point clouds at scale. Most current approaches build a single nearest-neighbor graph, discarding important geometric information. In contrast, HiPoNet forms higher-order simplicial complexes through learnable feature reweighting, generating multiple data views that disentangle distinct biological processes. It then employs simplicial wavelet transforms to extract multi-scale features - capturing both local and global topology. We empirically show that these components preserve topological information in the learned representations, and that HiPoNet significantly outperforms state-of-the-art point-cloud and graph-based models on single cell. We also show an application of HiPoNet on spatial transcriptomics datasets using spatial co-ordinates as one of the views. Overall, HiPoNet offers a robust and scalable solution for high-dimensional data analysis.
Principal Curvatures Estimation with Applications to Single Cell Data
Yanlei Zhang
Lydia Mezrag
Xingzhi Sun
Charles Xu
Kincaid MacDonald
Dhananjay Bhaskar
Bastian Rieck
Principal Curvatures Estimation with Applications to Single Cell Data
Yanlei Zhang
Lydia Mezrag
Xingzhi Sun
Charles Xu
Kincaid MacDonald
Dhananjay Bhaskar
Bastian Rieck
The rapidly growing field of single-cell transcriptomic sequencing (scRNAseq) presents challenges for data analysis due to its massive datas… (see more)ets. A common method in manifold learning consists in hypothesizing that datasets lie on a lower dimensional manifold. This allows to study the geometry of point clouds by extracting meaningful descriptors like curvature. In this work, we will present Adaptive Local PCA (AdaL-PCA), a data-driven method for accurately estimating various notions of intrinsic curvature on data manifolds, in particular principal curvatures for surfaces. The model relies on local PCA to estimate the tangent spaces. The evaluation of AdaL-PCA on sampled surfaces shows state-of-the-art results. Combined with a PHATE embedding, the model applied to single-cell RNA sequencing data allows us to identify key variations in the cellular differentiation.
Geometry-Aware Generative Autoencoder for Warped Riemannian Metric Learning and Generative Modeling on Data Manifolds
Xingzhi Sun
Danqi Liao
Kincaid MacDonald
Yanlei Zhang
Guillaume Huguet
Ian Adelstein
Tim G. J. Rudner
Rapid growth of high-dimensional datasets in fields such as single-cell RNA sequencing and spatial genomics has led to unprecedented opportu… (see more)nities for scientific discovery, but it also presents unique computational and statistical challenges. Traditional methods struggle with geometry-aware data generation, interpolation along meaningful trajectories, and transporting populations via feasible paths. To address these issues, we introduce Geometry-Aware Generative Autoencoder (GAGA), a novel framework that combines extensible manifold learning with generative modeling. GAGA constructs a neural network embedding space that respects the intrinsic geometries discovered by manifold learning and learns a novel warped Riemannian metric on the data space. This warped metric is derived from both the points on the data manifold and negative samples off the manifold, allowing it to characterize a meaningful geometry across the entire latent space. Using this metric, GAGA can uniformly sample points on the manifold, generate points along geodesics, and interpolate between populations across the learned manifold. GAGA shows competitive performance in simulated and real-world datasets, including a 30% improvement over SOTA in single-cell population-level trajectory inference.
Geometry-Aware Generative Autoencoders for Warped Riemannian Metric Learning and Generative Modeling on Data Manifolds
Xingzhi Sun
Danqi Liao
Kincaid MacDonald
Yanlei Zhang
Guillaume Huguet
Chen Liu
Ian Adelstein
Tim G. J. Rudner
Mapping the gene space at single-cell resolution with gene signal pattern analysis
Aarthi Venkat
M. Damo
Samuel Leone
Scott E. Youlten
Eric Fagerberg
John Attanasio
Nikhil S. Joshi
Michael Perlmutter
In single-cell sequencing analysis, several computational methods have been developed to map the cellular state space, but little has been d… (see more)one to map or create embeddings of the gene space. Here, we formulate the gene embedding problem, design tasks with simulated single-cell data to evaluate representations, and establish ten relevant baselines. We then present a graph signal processing approach we call gene signal pattern analysis (GSPA) that learns rich gene representations from single-cell data using a dictionary of diffusion wavelets on the cell-cell graph. GSPA enables characterization of genes based on their patterning on the cellular manifold. It also captures how localized or diffuse the expression of a gene is, for which we present a score called the gene localization score. We motivate and demonstrate the efficacy of GSPA as a framework for a range of biological tasks, such as capturing gene coexpression modules, condition-specific enrichment, and perturbation-specific gene-gene interactions. Then, we showcase the broad utility of gene rep-resentations derived from GSPA, including for cell-cell communication (GSPA-LR), spatial transcriptomics (GSPA-multimodal), and patient response (GSPA-Pt) analysis.
Beta cells are essential drivers of pancreatic ductal adenocarcinoma development
Cathy C. Garcia
Aarthi Venkat
Daniel C. McQuaid
Sherry Agabiti
Alex Tong
Rebecca L. Cardone
Rebecca Starble
Akin Sogunro
Jeremy B. Jacox
Christian F. Ruiz
Richard G. Kibbey
Mandar Deepak Muzumdar
Pancreatic endocrine-exocrine crosstalk plays a key role in normal physiology and disease. For instance, endocrine islet beta (β) cell secr… (see more)etion of insulin or cholecystokinin (CCK) promotes progression of pancreatic adenocarcinoma (PDAC), an exocrine cell-derived tumor. However, the cellular and molecular mechanisms that govern endocrine-exocrine signaling in tumorigenesis remain incompletely understood. We find that β cell ablation impedes PDAC development in mice, arguing that the endocrine pancreas is critical for exocrine tumorigenesis. Conversely, obesity induces β cell hormone dysregulation, alters CCK-dependent peri-islet exocrine cell transcriptional states, and enhances islet proximal tumor formation. Single-cell RNA-sequencing, in silico latent-space archetypal and trajectory analysis, and genetic lineage tracing in vivo reveal that obesity stimulates postnatal immature β cell expansion and adaptation towards a pro-tumorigenic CCK+ state via JNK/cJun stress-responsive signaling. These results define endocrine-exocrine signaling as a driver of PDAC development and uncover new avenues to target the endocrine pancreas to subvert exocrine tumorigenesis.
Exploring the Manifold of Neural Networks Using Diffusion Geometry
Elliott Abel
Peyton Crevasse
Yvan Grinspan
Selma Mazioud
Folu Ogundipe
Kristof Reimann
Ellie Schueler
Andrew J. Steindl
Ellen Zhang
Dhananjay Bhaskar
Siddharth Viswanath
Yanlei Zhang
Tim G. J. Rudner
Ian Adelstein
Drawing motivation from the manifold hypothesis, which posits that most high-dimensional data lies on or near low-dimensional manifolds, we … (see more)apply manifold learning to the space of neural networks. We learn manifolds where datapoints are neural networks by introducing a distance between the hidden layer representations of the neural networks. These distances are then fed to the non-linear dimensionality reduction algorithm PHATE to create a manifold of neural networks. We characterize this manifold using features of the representation, including class separation, hierarchical cluster structure, spectral entropy, and topological structure. Our analysis reveals that high-performing networks cluster together in the manifold, displaying consistent embedding patterns across all these features. Finally, we demonstrate the utility of this approach for guiding hyperparameter optimization and neural architecture search by sampling from the manifold.
Exploring the Manifold of Neural Networks Using Diffusion Geometry
Elliott Abel
Peyton Crevasse
Yvan Grinspan
Selma Mazioud
Folu Ogundipe
Kristof Reimann
Ellie Schueler
Andrew J. Steindl
Ellen Zhang
Dhananjay Bhaskar
Siddharth Viswanath
Yanlei Zhang
Tim G. J. Rudner
Ian Adelstein
Drawing motivation from the manifold hypothesis, which posits that most high-dimensional data lies on or near low-dimensional manifolds, we … (see more)apply manifold learning to the space of neural networks. We learn manifolds where datapoints are neural networks by introducing a distance between the hidden layer representations of the neural networks. These distances are then fed to the non-linear dimensionality reduction algorithm PHATE to create a manifold of neural networks. We characterize this manifold using features of the representation, including class separation, hierarchical cluster structure, spectral entropy, and topological structure. Our analysis reveals that high-performing networks cluster together in the manifold, displaying consistent embedding patterns across all these features. Finally, we demonstrate the utility of this approach for guiding hyperparameter optimization and neural architecture search by sampling from the manifold.
Deep Learning Unlocks the True Potential of Organ Donation after Circulatory Death with Accurate Prediction of Time-to-Death
Xingzhi Sun
Edward De Brouwer
Chen Liu
Ramesh Batra
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Increasing the number of organ donations after circulatory death (DCD) has been identified as one of the most important ways of addressing t… (see more)he ongoing organ shortage. While recent technological advances in organ transplantation have increased their success rate, a substantial challenge in increasing the number of DCD donations resides in the uncertainty regarding the timing of cardiac death after terminal extubation, impacting the risk of prolonged ischemic organ injury, and negatively affecting post-transplant outcomes. In this study, we trained and externally validated an ODE-RNN model, which combines recurrent neural network with neural ordinary equations and excels in processing irregularly-sampled time series data. The model is designed to predict time-to-death following terminal extubation in the intensive care unit (ICU) using the last 24 hours of clinical observations. Our model was trained on a cohort of 3,238 patients from Yale New Haven Hospital, and validated on an external cohort of 1,908 patients from six hospitals across Connecticut. The model achieved accuracies of 95.3 {+/-} 1.0% and 95.4 {+/-} 0.7% for predicting whether death would occur in the first 30 and 60 minutes, respectively, with a calibration error of 0.024 {+/-} 0.009. Heart rate, respiratory rate, mean arterial blood pressure (MAP), oxygen saturation (SpO2), and Glasgow Coma Scale (GCS) scores were identified as the most important predictors. Surpassing existing clinical scores, our model sets the stage for reduced organ acquisition costs and improved post-transplant outcomes.