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Inverse problems can be described as limited-data problems in which the signal of interest cannot be observed directly. A physics-based forward model that relates the signal with the observations is typically needed. Unfortunately, unknown…

Signal Processing · Electrical Eng. & Systems 2025-07-08 Alexandra Koulouri , Ville Rimpilainen

The problem of reconstructing brain activity from electric potential measurements performed on the surface of a human head is not an easy task: not just because the solution of the related inverse problem is fundamentally ill-posed (not…

Numerical Analysis · Mathematics 2023-08-11 Santtu Söderholm , Joonas Lahtinen , Carsten H. Wolters , Sampsa Pursiainen

In this paper, we present a robust version of the well-known exact low-resolution electromagnetic tomography (eLORETA) technique, named ReLORETA, to localize brain sources in the presence of different forward model uncertainties. Methods:…

Computational Engineering, Finance, and Science · Computer Science 2024-05-10 A. Noroozi , M. Ravan , B. Razavi , R. S. Fisher , Y. Law , M. S. Hasan

Subcortical structures play a critical role in brain function. However, options for assessing electrophysiological activity in these structures are limited. Electromagnetic fields generated by neuronal activity in subcortical structures can…

Invasive intracranial electroencephalography (iEEG) or electrocorticography (ECoG) measures electric potential directly on the surface of the brain and can be used to inform treatment planning for epilepsy surgery. Combined with numerical…

The electroencephalography (EEG) forward problem, the computation of the electric potential generated by a known electric current source configuration in the brain, is a key step of EEG source analysis. In this problem, it is often desired…

Medical Physics · Physics 2019-03-28 Axelle Pillain , Lyes Rahmouni , Francesco Andriulli

EEG Source localization is a critical tool in neuroscience, with applications ranging from epilepsy diagnosis to cognitive research. It involves solving an ill-posed inverse problem that lacks a unique solution unless constrained by prior…

Numerical Analysis · Mathematics 2025-08-01 Dilshanie Prasikala , Joonas Lahtinen , Alexandra Koulouri , Sampsa Pursiainen

Detecting where and when brain regions activate in a cognitive task or in a given clinical condition is the promise of non-invasive techniques like magnetoencephalography (MEG) or electroencephalography (EEG). This problem, referred to as…

Machine Learning · Statistics 2020-11-26 Jérôme-Alexis Chevalier , Alexandre Gramfort , Joseph Salmon , Bertrand Thirion

Source imaging based on magnetoencephalography (MEG) and electroencephalography (EEG) allows for the non-invasive analysis of brain activity with high temporal and good spatial resolution. As the bioelectromagnetic inverse problem is…

Applications · Statistics 2016-07-29 Daniel Strohmeier , Yousra Bekhti , Jens Haueisen , Alexandre Gramfort

We deal with estimation of multiple dipoles from combined MEG and EEG time--series. We use a sequential Monte Carlo algorithm to characterize the posterior distribution of the number of dipoles and their locations. By considering three test…

Quantitative Methods · Quantitative Biology 2017-06-20 Filippo Rossi , Gianvittorio Luria , Sara Sommariva , Alberto Sorrentino

In this paper, we focus on the inverse problem of reconstructing distributional brain activity with cortical and weakly detectable deep components in non-invasive Electroencephalography. In particular, we aim to generalize the previously…

Numerical Analysis · Mathematics 2022-03-16 Joonas Lahtinen , Alexandra Koulouri , Atena Rezaei , Sampsa Pursiainen

Knowing the correct skull conductivity is crucial for the accuracy of EEG source imaging, but unfortunately, its true value, which is inter- and intra-individually varying, is difficult to determine. In this paper, we propose a statistical…

Medical Physics · Physics 2020-09-07 Ville Rimpiläinen , Alexandra Koulouri , Felix Lucka , Jari P Kaipio , Carsten H Wolters

Magnetoencephalographic (MEG) measurements record magnetic fields generated from neurons while information is being processed in the brain. The inverse problem of identifying sources of biomagnetic fields and deducing their intensities from…

Neurons and Cognition · Quantitative Biology 2009-11-11 Hung-I Pai , Chih-Yuan Tseng , HC Lee

EEG source localization is an important technical issue in EEG analysis. Despite many numerical methods existed for EEG source localization, they all rely on strong priors and the deep sources are intractable. Here we propose a deep…

Machine Learning · Computer Science 2021-06-17 Chen Wei , Kexin Lou , Zhengyang Wang , Mingqi Zhao , Dante Mantini , Quanying Liu

We present a novel solution to the problem of localization of MEG and EEG brain signals. The solution is sequential and iterative, and is based on minimizing the least-squares (LS)criterion by the Alternating Projection (AP) algorithm,…

Signal Processing · Electrical Eng. & Systems 2020-11-26 Amir Adler , Mati Wax , Dimitrios Pantazis

In this paper we present a new discretization strategy for the boundary element formulation of the Electroencephalography (EEG) forward problem. Boundary integral formulations, classically solved with the Boundary Element Method (BEM), are…

Medical Physics · Physics 2016-03-22 Lyes Rahmouni , Simon Adrian , Kristof Cools , Francesco P. Andriulli

State-space models are widely employed across various research disciplines to study unobserved dynamics. Conventional estimation techniques, such as Kalman filtering and expectation maximisation, offer valuable insights but incur high…

Computation · Statistics 2023-11-28 Jose M. Sanchez-Bornot , Roberto C. Sotero , Scott Kelso , Damien Coyle

Bayesian inference for inverse problems hinges critically on the choice of priors. In the absence of specific prior information, population-level distributions can serve as effective priors for parameters of interest. With the advent of…

Instrumentation and Methods for Astrophysics · Physics 2025-02-11 Gabriel Missael Barco , Alexandre Adam , Connor Stone , Yashar Hezaveh , Laurence Perreault-Levasseur

We describe a novel method for dynamic estimation of multi-dipole states from Magneto/Electro-encephalography (M/EEG) time series. The new approach builds on the recent development of particle filters for M/EEG; these algorithms…

Numerical Analysis · Mathematics 2016-03-18 Valentina Vivaldi , Alberto Sorrentino

Bayesian learning provides a unified skeleton to solve the electrophysiological source imaging task. From this perspective, existing source imaging algorithms utilize the Gaussian assumption for the observation noise to build the likelihood…

Machine Learning · Computer Science 2025-08-07 Yuanhao Li , Badong Chen , Zhongxu Hu , Keita Suzuki , Wenjun Bai , Yasuharu Koike , Okito Yamashita