VLDB 2026 Research / reviewers in the wild / expert
Erdem Varol
dblp:117/0511
· DBLP profile ↗
18ranked-venue papers
6as first author
10since 2021 · last 2025
0000-0002-6128-8939ORCID · corroborated
Domains — the database's venue-derived domains; a paper can count in several
Graphics, computer vision, multimedia, augmented reality and games · 13 · 6 first-author · 5 since 2021Applied, interdisciplinary, general and emerging computing · 10 · 5 first-author · 2 since 2021Artificial intelligence and machine learning · 4 · 4 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | Self supervised learning for in vivo localization of microelectrode arrays using raw local field potentialabstractRecent advances in large-scale neural recordings have enabled accurate decoding of behavior and cognitive states, yet decoding anatomical regions remains underexplored, despite being crucial for consistent targeting in multiday recordings and effective deep brain stimulation. Current approaches typically rely on external anatomical information, from atlas-based planning to post hoc histology, which are limited in precision, longitudinal applicability, and real-time feedback. In this work, we develop a self-supervised learning framework, Lfp2vec, to infer anatomical regions directly from the neural signal in vivo. We adapt an audio-pretrained transformer model by continuing self-supervised training on a large corpus of unlabeled local-field-potential (LFP) data, then fine-tuning for anatomical region decoding. Ablations show that combining out-of-domain initialization with in-domain self-supervision outperforms training from scratch. We demonstrate that our method achieves strong zero-shot generalization across different labs and probe geometries, and outperforming state-of-the-art self-supervised models on electrophysiology data. The learned embeddings form anatomically coherent clusters and transfer effectively to downstream tasks like disease classification with minimal fine-tuning. Altogether, our approach enables zero-shot prediction of brain regions in novel subjects, demonstrates that LFP signals encode rich anatomical information, and establishes self-supervised learning on raw LFP as a foundation to learn representations that can be tuned for diverse neural decoding tasks. Code to reproduce our results is found in the github repository at https://github.com/tianxiao18/lfp2vec. Tianxiao He, Malhar Patel, Anna Maslarova, Mihály Vöröslakos, Nalini Ramanathan, Wei-Lun Hung, György Buzsáki, Erdem Varol |
NeurIPS | 9 |
| 2025 | Predicting Functional Brain Connectivity with Context-Aware Deep Neural NetworksabstractSpatial location and molecular interactions have long been linked to the connectivity
patterns of neural circuits. Yet, at the macroscale of human brain networks,
the interplay between spatial position, gene expression, and connectivity remains
incompletely understood. Recent efforts to map the human transcriptome and
connectome have yielded spatially resolved brain atlases, however modeling the
relationship between high-dimensional transcriptomic data and connectivity while
accounting for inherent spatial confounds presents a significant challenge. In this
paper, we present the first deep learning approaches for predicting whole-brain
functional connectivity from gene expression and regional spatial coordinates, including
our proposed Spatiomolecular Transformer (SMT). SMT explicitly models
biological context by tokenizing genes based on their transcription start site (TSS)
order to capture multi-scale genomic organization, and incorporating regional
3D spatial location via a dedicated context [CLS] token within its multi-head
self-attention mechanism. We rigorously benchmark context-aware neural networks,
including SMT and a single-gene resolution Multilayer-Perceptron (MLP),
to established rules-based and bilinear methods. Crucially, to ensure that learned
relationships in any model are not mere artifacts of spatial proximity, we introduce
novel spatiomolecular null maps preserving key transcriptomic autocorrelation
structure. Context-aware neural networks outperform linear methods, significantly
exceed our stringent null map estimates, and generalize across diverse connectomic
datasets and parcellation resolutions. Together, these findings demonstrate a
strong, predictable link between the spatial distributions of gene expression and
functional brain network architecture, and establish a rigorously validated deep
learning framework for decoding this relationship. Code to reproduce our results is
available at: github.com/neuroinfolab/GeneEx2Conn. Alexander Ratzan, Sidharth Goel, Junhao Wen 0002, Christos Davatzikos, Erdem Varol |
NeurIPS | 5 |
| 2023 | Multimodal Microscopy Image Alignment Using Spatial and Shape Information and a Branch-and-Bound AlgorithmabstractMultimodal microscopy experiments that image the same population of cells under different experimental conditions have become a widely used approach in systems and molecular neuroscience. The main obstacle is to align the different imaging modalities to obtain complementary information about the observed cell population (e.g., gene expression and calcium signal). Traditional image registration methods perform poorly when only a small subset of cells are present in both images, as is common in multimodal experiments. We cast multimodal microscopy alignment as a cell subset matching problem. To solve this non-convex problem, we introduce an efficient and globally optimal branch-and-bound algorithm to find subsets of point clouds that are in rotational alignment with each other. In addition, we use complementary information about cell shape and location to compute the matching likelihood of cell pairs in two imaging modalities to further prune the optimization search tree. Finally, we use the maximal set of cells in rigid rotational alignment to seed image deformation fields to obtain a final registration result. Our framework performs better than the state-of-the-art histology alignment approaches regarding matching quality and is faster than manual alignment, providing a viable solution to improve the throughput of multimodal microscopy experiments. Shuonan Chen, Bovey Y. Rao, Stephanie Herrlinger, Attila Losonczy, Liam Paninski, Erdem Varol |
ICASSP | 6 |
| 2023 | Robust Online Multiband Drift Estimation in Electrophysiology DataabstractHigh-density electrophysiology probes have opened new possibilities for systems neuroscience in human and non-human animals, but probe motion poses a challenge for downstream analyses, particularly in human recordings. We improve on the state of the art for tracking this motion with four major contributions. First, we extend previous decentralized methods to use multiband information, leveraging the local field potential (LFP) in addition to spikes. Second, we show that the LFP-based approach enables registration at sub-second temporal resolution. Third, we introduce an efficient online motion tracking algorithm, enabling the method to scale up to longer and higher-resolution recordings, and possibly facilitating real-time applications. Finally, we improve the robustness of the approach by introducing a structure-aware objective and simple methods for adaptive parameter selection. Together, these advances enable fully automated scalable registration of challenging datasets from human and mouse. Charles Windolf, Angelique C. Paulk, Yoav Kfir, Eric Trautmann, Domokos Meszéna, William Muñoz, Irene Caprara, Mohsen Jamali, Julien Boussard, Ziv Williams, Sydney S. Cash, Liam Paninski, Erdem Varol |
ICASSP | 13 |
| 2023 | Bypassing spike sorting: Density-based decoding using spike localization from dense multielectrode probesabstractNeural decoding and its applications to brain computer interfaces (BCI) are essential for understanding the association between neural activity and behavior. A prerequisite for many decoding approaches is spike sorting, the assignment of action potentials (spikes) to individual neurons. Current spike sorting algorithms, however, can be inaccurate and do not properly model uncertainty of spike assignments, therefore discarding information that could potentially improve decoding performance. Recent advances in high-density probes (e.g., Neuropixels) and computational methods now allow for extracting a rich set of spike features from unsorted data; these features can in turn be used to directly decode behavioral correlates. To this end, we propose a spike sorting-free decoding method that directly models the distribution of extracted spike features using a mixture of Gaussians (MoG) encoding the uncertainty of spike assignments, without aiming to solve the spike clustering problem explicitly. We allow the mixing proportion of the MoG to change over time in response to the behavior and develop variational inference methods to fit the resulting model and to perform decoding. We benchmark our method with an extensive suite of recordings from different animals and probe geometries, demonstrating that our proposed decoder can consistently outperform current methods based on thresholding (i.e. multi-unit activity) and spike sorting. Open source code is available at https://github.com/yzhang511/density_decoding. Yizi Zhang, Tianxiao He, Julien Boussard, Charles Windolf, Olivier Winter, Eric Trautmann, Noam Roth, Hailey Barrell, Mark Churchland, Nicholas A. Steinmetz, Erdem Varol, Cole L. Hurwitz, Liam Paninski |
NeurIPS | 11 |
| 2022 | Multi-scale semi-supervised clustering of brain images: Deriving disease subtypes
Junhao Wen 0002, Erdem Varol, Aristeidis Sotiras, Zhijian Yang, Ganesh B. Chand, Güray Erus, Haochang Shou, Ahmed Abdulkadir, Gyujoon Hwang, Dominic B. Dwyer, Alessandro Pigoni, Paola Dazzan, René S. Kahn, Hugo G. Schnack, Marcus V. Zanetti, Eva M. Meisenzahl, Geraldo Filho Bussato, Benedicto Crespo-Facorro, Rafael Romero-Garcia, Christos Pantelis, Stephen J. Wood, Chuanjun Zhuo, Russell T. Shinohara, Yong Fan 0001, Ruben C. Gur, Raquel E. Gur, Theodore D. Satterthwaite, Nikolaos Koutsouleris, Daniel H. Wolf, Christos Davatzikos |
Medical Image Anal. | 2 |
| 2021 | Decentralized Motion Inference and Registration of Neuropixel DataabstractMulti-electrode arrays such as "Neuropixels" probes enable the study of neuronal voltage signals at high temporal and single-cell spatial resolution. However, in vivo recordings from these devices often experience some shifting of the probe (due e.g. to animal movement), resulting in poorly localized voltage readings that in turn can corrupt estimates of neural activity. We introduce a new registration method to partially correct for this motion. In contrast to previous template-based registration methods, the proposed approach is decentralized, estimating shifts of the data recorded in multiple timebins with respect to one another, and then extracting a global registration estimate from the resulting estimated shift matrix. We find that the resulting decentralized registration is more robust and accurate than previous template-based approaches applied to both simulated and real data, but nonetheless some significant non-stationarity in the recovered neural activity remains that should be accounted for by downstream processing pipelines. Open source code is available at https://github.com/evarol/NeuropixelsRegistration. Erdem Varol, Julien Boussard, Nishchal Dethe, Olivier Winter, Anne E. Urai, Anne Churchland, Nick Steinmetz, Liam Paninski |
ICASSP | 1 |
| 2021 | Non-parametric Vignetting Correction for Sparse Spatial Transcriptomics Images
Bovey Y. Rao, Alexis M. Peterson, Elena K. Kandror, Stephanie Herrlinger, Attila Losonczy, Liam Paninski, Abbas H. Rizvi, Erdem Varol |
MICCAI (8) | 8 |
| 2021 | Three-dimensional spike localization and improved motion correction for Neuropixels recordingsabstractNeuropixels (NP) probes are dense linear multi-electrode arrays that have rapidly become essential tools for studying the electrophysiology of large neural populations. Unfortunately, a number of challenges remain in analyzing the large datasets output by these probes. Here we introduce several new methods for extracting useful spiking information from NP probes. First, we use a simple point neuron model, together with a neural-network denoiser, to efficiently map spikes detected on the probe into three-dimensional localizations. Previous methods localized spikes in two dimensions only; we show that the new localization approach is significantly more robust and provides an improved feature set for clustering spikes according to neural identity (``spike sorting"). Next, we apply a Poisson denoising method to the resulting three-dimensional point-cloud representation of the data, and show that the resulting 3D images can be accurately registered over time, leading to improved tracking of time-varying neural activity over the probe, and in turn, crisper estimates of neural clusters over time. The code to reproduce our results and an example neuropixels dataset is provided in the supplementary material. Julien Boussard, Erdem Varol, Hyun Dong Lee, Nishchal Dethe, Liam Paninski |
NeurIPS | 2 |
| 2021 | Neuron matching in C. elegans with robust approximate linear regression without correspondenceabstractWe propose methods for estimating correspondence between two point sets under the presence of outliers in both the source and target sets. The proposed algorithms expand upon the theory of the regression without correspondence problem to estimate transformation coefficients using unordered multisets of covariates and responses. Previous theoretical analysis of the problem has been done in a setting where the responses are a complete permutation of the regressed covariates. This paper expands the problem setting by analyzing the cases where only a subset of the responses is a permutation of the regressed covariates in addition to some covariates possibly being adversarial outliers. We term this problem robust regression without correspondence and provide several algorithms based on random sample consensus for exact and approximate recovery in a noiseless and noisy one-dimensional setting as well as an approximation algorithm for multiple dimensions. The theoretical guarantees of the algorithms are verified in simulated data. We demonstrate an important computational neuroscience application of the proposed framework by demonstrating its effectiveness in a Caenorhabditis elegans neuron matching problem where the presence of outliers in both the source and target nematodes is a natural tendency. Open source code implementing this method is available at https://github.com/amin-nejat/RRWOC. Amin Nejatbakhsh, Erdem Varol |
WACV | 2 |
| 2020 | Probabilistic Joint Segmentation and Labeling of C. elegans Neurons
Amin Nejatbakhsh, Erdem Varol, Eviatar Yemini, Oliver Hobert, Liam Paninski |
MICCAI (5) | 2 |
| 2020 | Demixing Calcium Imaging Data in C. elegans via Deformable Non-negative Matrix Factorization
Amin Nejatbakhsh, Erdem Varol, Eviatar Yemini, Vivek Venkatachalam, Aravinthan D. T. Samuel, Oliver Hobert, Liam Paninski |
MICCAI (5) | 2 |
| 2020 | Statistical Atlas of C. elegans Neurons
Erdem Varol, Amin Nejatbakhsh, Ruoxi Sun 0006, Gonzalo E. Mena, Eviatar Yemini, Oliver Hobert, Liam Paninski |
MICCAI (5) | 1 |
| 2020 | MAGIC: Multi-scale Heterogeneity Analysis and Clustering for Brain Diseases
Junhao Wen 0002, Erdem Varol, Ganesh B. Chand, Aristeidis Sotiras, Christos Davatzikos |
MICCAI (7) | 2 |
| 2018 | Generative Discriminative Models for Multivariate Inference and Statistical Mapping in Medical Imaging
Erdem Varol, Aristeidis Sotiras, Christos Davatzikos |
MICCAI (3) | 1 |
| 2016 | Structured Outlier Detection in Neuroimaging Studies with Minimal Convex Polytopes
Erdem Varol, Aristeidis Sotiras, Christos Davatzikos |
MICCAI (1) | 1 |
| 2015 | Disentangling Disease Heterogeneity with Max-Margin Multiple Hyperplane Classifier
Erdem Varol, Aristeidis Sotiras, Christos Davatzikos |
MICCAI (1) | 1 |
| 2014 | Supervised Block Sparse Dictionary Learning for Simultaneous Clustering and Classification in Computational Anatomy
Erdem Varol, Christos Davatzikos |
MICCAI (2) | 1 |