A neuroscientist whose published research has been embroiled in accusations of image manipulation and duplication has announced his resignation from the University of Minnesota, effective March 1.

Sylvain Lesné had continued his research at the U in recent years, even as concerns emerged and compelled a retraction last year of one of his landmark papers that had pointed to new directions in treating Alzheimer's disease.

A university spokesperson confirmed the resignation in a written statement Monday — without explanation as to why — but noted the university has recently alerted medical journals to "data integrity concerns" with four additional publications Lesné co-authored.

"The University ... has been in touch with those journals to recommend retraction of the publications, where appropriate," the spokesperson said.

Lesné did not respond to a request for comment Tuesday. He had been the only author to object last year when co-authors agreed to retract their 2006 paper, published in the prestigious journal Nature, that identified a promising molecular target for treating of Alzheimer's.

The target was called Aβ*56 in studies, or phonetically as abeta star 56. Mice mimicking that molecule showed worse memory loss based on their ability to navigate a maze, according to the original research. The U scientists theorized that a drug targeting the molecule could help people overcome the debilitating effects of Alzheimer's, an incurable disease and a leading cause of dementia and death in America's aging population.

While a review by the university found no research misconduct related to the paper, the authors in their retraction said key images showed "signs of excessive manipulation, including splicing, duplication and the use of an eraser tool."

Senior author Karen Ashe said last year she had agreed to the retraction in part because more recent research had duplicated and supported her team's original findings about abeta star 56. Her work has also moved on to other potential molecular targets for treating Alzheimer's.

A cottage industry of scientists, who used computer techniques to identify suspicious or duplicate images in published papers, ensnared the U's Alzheimer's research. Many had also previously raised concerns about images in four papers that the U has now referred to journals for possible retractions.

Lesné was the senior author of three of the suspect papers and a contributing writer for the fourth. All focus on the role of molecules such as abeta star 56 and whether they influence the onset or course of Alzheimer's.

The U authors already corrected one in 2022, though they said at the time the incorrect images had no impact on the overall results. Journal editors updated another one that same year with an expression of concern about the accuracy of its images.

The studies rely on western blotting, a tool researchers commonly use to visually represent the amount of proteins found through their experiments in blood or tissue. Critics questioned images in the studies that appeared duplicated, sometimes in reverse, and whether those errors were cosmetic or fundamentally changed the results.

Critics also questioned the slow pace of the U's internal reviews, which allowed the original results to stand for years and potentially misguide other scientists about where to focus their Alzheimer's research.

Science journalist Charles Piller documented some of the first imaging concerns and highlighted Lesné's resignation in a social media post Monday, stating "a giant shoe finally drops."